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This is gdb.info, produced by makeinfo version 4.6 from ./gdb.texinfo.
INFO-DIR-SECTION Software development
START-INFO-DIR-ENTRY
* Gdb: (gdb). The GNU debugger.
END-INFO-DIR-ENTRY
This file documents the GNU debugger GDB.
This is the Ninth Edition, of `Debugging with GDB: the GNU
Source-Level Debugger' for GDB Version 6.1.1.
Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
1998,
1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software" and "Free Software Needs Free
Documentation", with the Front-Cover Texts being "A GNU Manual," and
with the Back-Cover Texts as in (a) below.
(a) The Free Software Foundation's Back-Cover Text is: "You have
freedom to copy and modify this GNU Manual, like GNU software. Copies
published by the Free Software Foundation raise funds for GNU
development."
File: gdb.info, Node: M2 Constants, Next: M2 Defaults, Prev: Built-In Func/Proc, Up: Modula-2
Constants
.........
GDB allows you to express the constants of Modula-2 in the following
ways:
* Integer constants are simply a sequence of digits. When used in an
expression, a constant is interpreted to be type-compatible with
the rest of the expression. Hexadecimal integers are specified by
a trailing `H', and octal integers by a trailing `B'.
* Floating point constants appear as a sequence of digits, followed
by a decimal point and another sequence of digits. An optional
exponent can then be specified, in the form `E[+|-]NNN', where
`[+|-]NNN' is the desired exponent. All of the digits of the
floating point constant must be valid decimal (base 10) digits.
* Character constants consist of a single character enclosed by a
pair of like quotes, either single (`'') or double (`"'). They may
also be expressed by their ordinal value (their ASCII value,
usually) followed by a `C'.
* String constants consist of a sequence of characters enclosed by a
pair of like quotes, either single (`'') or double (`"'). Escape
sequences in the style of C are also allowed. *Note C and C++
constants: C Constants, for a brief explanation of escape
sequences.
* Enumerated constants consist of an enumerated identifier.
* Boolean constants consist of the identifiers `TRUE' and `FALSE'.
* Pointer constants consist of integral values only.
* Set constants are not yet supported.
File: gdb.info, Node: M2 Defaults, Next: Deviations, Prev: M2 Constants, Up: Modula-2
Modula-2 defaults
.................
If type and range checking are set automatically by GDB, they both
default to `on' whenever the working language changes to Modula-2.
This happens regardless of whether you or GDB selected the working
language.
If you allow GDB to set the language automatically, then entering
code compiled from a file whose name ends with `.mod' sets the working
language to Modula-2. *Note Having GDB set the language automatically:
Automatically, for further details.
File: gdb.info, Node: Deviations, Next: M2 Checks, Prev: M2 Defaults, Up: Modula-2
Deviations from standard Modula-2
.................................
A few changes have been made to make Modula-2 programs easier to debug.
This is done primarily via loosening its type strictness:
* Unlike in standard Modula-2, pointer constants can be formed by
integers. This allows you to modify pointer variables during
debugging. (In standard Modula-2, the actual address contained in
a pointer variable is hidden from you; it can only be modified
through direct assignment to another pointer variable or
expression that returned a pointer.)
* C escape sequences can be used in strings and characters to
represent non-printable characters. GDB prints out strings with
these escape sequences embedded. Single non-printable characters
are printed using the `CHR(NNN)' format.
* The assignment operator (`:=') returns the value of its right-hand
argument.
* All built-in procedures both modify _and_ return their argument.
File: gdb.info, Node: M2 Checks, Next: M2 Scope, Prev: Deviations, Up: Modula-2
Modula-2 type and range checks
..............................
_Warning:_ in this release, GDB does not yet perform type or range
checking.
GDB considers two Modula-2 variables type equivalent if:
* They are of types that have been declared equivalent via a `TYPE
T1 = T2' statement
* They have been declared on the same line. (Note: This is true of
the GNU Modula-2 compiler, but it may not be true of other
compilers.)
As long as type checking is enabled, any attempt to combine variables
whose types are not equivalent is an error.
Range checking is done on all mathematical operations, assignment,
array index bounds, and all built-in functions and procedures.
File: gdb.info, Node: M2 Scope, Next: GDB/M2, Prev: M2 Checks, Up: Modula-2
The scope operators `::' and `.'
................................
There are a few subtle differences between the Modula-2 scope operator
(`.') and the GDB scope operator (`::'). The two have similar syntax:
MODULE . ID
SCOPE :: ID
where SCOPE is the name of a module or a procedure, MODULE the name of
a module, and ID is any declared identifier within your program, except
another module.
Using the `::' operator makes GDB search the scope specified by
SCOPE for the identifier ID. If it is not found in the specified
scope, then GDB searches all scopes enclosing the one specified by
SCOPE.
Using the `.' operator makes GDB search the current scope for the
identifier specified by ID that was imported from the definition module
specified by MODULE. With this operator, it is an error if the
identifier ID was not imported from definition module MODULE, or if ID
is not an identifier in MODULE.
File: gdb.info, Node: GDB/M2, Prev: M2 Scope, Up: Modula-2
GDB and Modula-2
................
Some GDB commands have little use when debugging Modula-2 programs.
Five subcommands of `set print' and `show print' apply specifically to
C and C++: `vtbl', `demangle', `asm-demangle', `object', and `union'.
The first four apply to C++, and the last to the C `union' type, which
has no direct analogue in Modula-2.
The `@' operator (*note Expressions: Expressions.), while available
with any language, is not useful with Modula-2. Its intent is to aid
the debugging of "dynamic arrays", which cannot be created in Modula-2
as they can in C or C++. However, because an address can be specified
by an integral constant, the construct `{TYPE}ADREXP' is still useful.
In GDB scripts, the Modula-2 inequality operator `#' is interpreted
as the beginning of a comment. Use `<>' instead.
File: gdb.info, Node: Unsupported languages, Prev: Support, Up: Languages
Unsupported languages
=====================
In addition to the other fully-supported programming languages, GDB
also provides a pseudo-language, called `minimal'. It does not
represent a real programming language, but provides a set of
capabilities close to what the C or assembly languages provide. This
should allow most simple operations to be performed while debugging an
application that uses a language currently not supported by GDB.
If the language is set to `auto', GDB will automatically select this
language if the current frame corresponds to an unsupported language.
File: gdb.info, Node: Symbols, Next: Altering, Prev: Languages, Up: Top
Examining the Symbol Table
**************************
The commands described in this chapter allow you to inquire about the
symbols (names of variables, functions and types) defined in your
program. This information is inherent in the text of your program and
does not change as your program executes. GDB finds it in your
program's symbol table, in the file indicated when you started GDB
(*note Choosing files: File Options.), or by one of the file-management
commands (*note Commands to specify files: Files.).
Occasionally, you may need to refer to symbols that contain unusual
characters, which GDB ordinarily treats as word delimiters. The most
frequent case is in referring to static variables in other source files
(*note Program variables: Variables.). File names are recorded in
object files as debugging symbols, but GDB would ordinarily parse a
typical file name, like `foo.c', as the three words `foo' `.' `c'. To
allow GDB to recognize `foo.c' as a single symbol, enclose it in single
quotes; for example,
p 'foo.c'::x
looks up the value of `x' in the scope of the file `foo.c'.
`info address SYMBOL'
Describe where the data for SYMBOL is stored. For a register
variable, this says which register it is kept in. For a
non-register local variable, this prints the stack-frame offset at
which the variable is always stored.
Note the contrast with `print &SYMBOL', which does not work at all
for a register variable, and for a stack local variable prints the
exact address of the current instantiation of the variable.
`info symbol ADDR'
Print the name of a symbol which is stored at the address ADDR.
If no symbol is stored exactly at ADDR, GDB prints the nearest
symbol and an offset from it:
(gdb) info symbol 0x54320
_initialize_vx + 396 in section .text
This is the opposite of the `info address' command. You can use
it to find out the name of a variable or a function given its
address.
`whatis EXPR'
Print the data type of expression EXPR. EXPR is not actually
evaluated, and any side-effecting operations (such as assignments
or function calls) inside it do not take place. *Note
Expressions: Expressions.
`whatis'
Print the data type of `$', the last value in the value history.
`ptype TYPENAME'
Print a description of data type TYPENAME. TYPENAME may be the
name of a type, or for C code it may have the form `class
CLASS-NAME', `struct STRUCT-TAG', `union UNION-TAG' or `enum
ENUM-TAG'.
`ptype EXPR'
`ptype'
Print a description of the type of expression EXPR. `ptype'
differs from `whatis' by printing a detailed description, instead
of just the name of the type.
For example, for this variable declaration:
struct complex {double real; double imag;} v;
the two commands give this output:
(gdb) whatis v
type = struct complex
(gdb) ptype v
type = struct complex {
double real;
double imag;
}
As with `whatis', using `ptype' without an argument refers to the
type of `$', the last value in the value history.
`info types REGEXP'
`info types'
Print a brief description of all types whose names match REGEXP
(or all types in your program, if you supply no argument). Each
complete typename is matched as though it were a complete line;
thus, `i type value' gives information on all types in your
program whose names include the string `value', but `i type
^value$' gives information only on types whose complete name is
`value'.
This command differs from `ptype' in two ways: first, like
`whatis', it does not print a detailed description; second, it
lists all source files where a type is defined.
`info scope ADDR'
List all the variables local to a particular scope. This command
accepts a location--a function name, a source line, or an address
preceded by a `*', and prints all the variables local to the scope
defined by that location. For example:
(gdb) info scope command_line_handler
Scope for command_line_handler:
Symbol rl is an argument at stack/frame offset 8, length 4.
Symbol linebuffer is in static storage at address 0x150a18, length 4.
Symbol linelength is in static storage at address 0x150a1c, length 4.
Symbol p is a local variable in register $esi, length 4.
Symbol p1 is a local variable in register $ebx, length 4.
Symbol nline is a local variable in register $edx, length 4.
Symbol repeat is a local variable at frame offset -8, length 4.
This command is especially useful for determining what data to
collect during a "trace experiment", see *Note collect: Tracepoint
Actions.
`info source'
Show information about the current source file--that is, the
source file for the function containing the current point of
execution:
* the name of the source file, and the directory containing it,
* the directory it was compiled in,
* its length, in lines,
* which programming language it is written in,
* whether the executable includes debugging information for
that file, and if so, what format the information is in
(e.g., STABS, Dwarf 2, etc.), and
* whether the debugging information includes information about
preprocessor macros.
`info sources'
Print the names of all source files in your program for which
there is debugging information, organized into two lists: files
whose symbols have already been read, and files whose symbols will
be read when needed.
`info functions'
Print the names and data types of all defined functions.
`info functions REGEXP'
Print the names and data types of all defined functions whose
names contain a match for regular expression REGEXP. Thus, `info
fun step' finds all functions whose names include `step'; `info
fun ^step' finds those whose names start with `step'. If a
function name contains characters that conflict with the regular
expression language (eg. `operator*()'), they may be quoted with
a backslash.
`info variables'
Print the names and data types of all variables that are declared
outside of functions (i.e. excluding local variables).
`info variables REGEXP'
Print the names and data types of all variables (except for local
variables) whose names contain a match for regular expression
REGEXP.
`info classes'
`info classes REGEXP'
Display all Objective-C classes in your program, or (with the
REGEXP argument) all those matching a particular regular
expression.
`info selectors'
`info selectors REGEXP'
Display all Objective-C selectors in your program, or (with the
REGEXP argument) all those matching a particular regular
expression.
Some systems allow individual object files that make up your
program to be replaced without stopping and restarting your
program. For example, in VxWorks you can simply recompile a
defective object file and keep on running. If you are running on
one of these systems, you can allow GDB to reload the symbols for
automatically relinked modules:
`set symbol-reloading on'
Replace symbol definitions for the corresponding source file
when an object file with a particular name is seen again.
`set symbol-reloading off'
Do not replace symbol definitions when encountering object
files of the same name more than once. This is the default
state; if you are not running on a system that permits
automatic relinking of modules, you should leave
`symbol-reloading' off, since otherwise GDB may discard
symbols when linking large programs, that may contain several
modules (from different directories or libraries) with the
same name.
`show symbol-reloading'
Show the current `on' or `off' setting.
`set opaque-type-resolution on'
Tell GDB to resolve opaque types. An opaque type is a type
declared as a pointer to a `struct', `class', or `union'--for
example, `struct MyType *'--that is used in one source file
although the full declaration of `struct MyType' is in another
source file. The default is on.
A change in the setting of this subcommand will not take effect
until the next time symbols for a file are loaded.
`set opaque-type-resolution off'
Tell GDB not to resolve opaque types. In this case, the type is
printed as follows:
{<no data fields>}
`show opaque-type-resolution'
Show whether opaque types are resolved or not.
`maint print symbols FILENAME'
`maint print psymbols FILENAME'
`maint print msymbols FILENAME'
Write a dump of debugging symbol data into the file FILENAME.
These commands are used to debug the GDB symbol-reading code. Only
symbols with debugging data are included. If you use `maint print
symbols', GDB includes all the symbols for which it has already
collected full details: that is, FILENAME reflects symbols for
only those files whose symbols GDB has read. You can use the
command `info sources' to find out which files these are. If you
use `maint print psymbols' instead, the dump shows information
about symbols that GDB only knows partially--that is, symbols
defined in files that GDB has skimmed, but not yet read
completely. Finally, `maint print msymbols' dumps just the
minimal symbol information required for each object file from
which GDB has read some symbols. *Note Commands to specify files:
Files, for a discussion of how GDB reads symbols (in the
description of `symbol-file').
`maint info symtabs [ REGEXP ]'
`maint info psymtabs [ REGEXP ]'
List the `struct symtab' or `struct partial_symtab' structures
whose names match REGEXP. If REGEXP is not given, list them all.
The output includes expressions which you can copy into a GDB
debugging this one to examine a particular structure in more
detail. For example:
(gdb) maint info psymtabs dwarf2read
{ objfile /home/gnu/build/gdb/gdb
((struct objfile *) 0x82e69d0)
{ psymtab /home/gnu/src/gdb/dwarf2read.c
((struct partial_symtab *) 0x8474b10)
readin no
fullname (null)
text addresses 0x814d3c8 -- 0x8158074
globals (* (struct partial_symbol **) 0x8507a08 @ 9)
statics (* (struct partial_symbol **) 0x40e95b78 @ 2882)
dependencies (none)
}
}
(gdb) maint info symtabs
(gdb)
We see that there is one partial symbol table whose filename
contains the string `dwarf2read', belonging to the `gdb'
executable; and we see that GDB has not read in any symtabs yet at
all. If we set a breakpoint on a function, that will cause GDB to
read the symtab for the compilation unit containing that function:
(gdb) break dwarf2_psymtab_to_symtab
Breakpoint 1 at 0x814e5da: file /home/gnu/src/gdb/dwarf2read.c,
line 1574.
(gdb) maint info symtabs
{ objfile /home/gnu/build/gdb/gdb
((struct objfile *) 0x82e69d0)
{ symtab /home/gnu/src/gdb/dwarf2read.c
((struct symtab *) 0x86c1f38)
dirname (null)
fullname (null)
blockvector ((struct blockvector *) 0x86c1bd0) (primary)
debugformat DWARF 2
}
}
(gdb)
File: gdb.info, Node: Altering, Next: GDB Files, Prev: Symbols, Up: Top
Altering Execution
******************
Once you think you have found an error in your program, you might want
to find out for certain whether correcting the apparent error would
lead to correct results in the rest of the run. You can find the
answer by experiment, using the GDB features for altering execution of
the program.
For example, you can store new values into variables or memory
locations, give your program a signal, restart it at a different
address, or even return prematurely from a function.
* Menu:
* Assignment:: Assignment to variables
* Jumping:: Continuing at a different address
* Signaling:: Giving your program a signal
* Returning:: Returning from a function
* Calling:: Calling your program's functions
* Patching:: Patching your program
File: gdb.info, Node: Assignment, Next: Jumping, Up: Altering
Assignment to variables
=======================
To alter the value of a variable, evaluate an assignment expression.
*Note Expressions: Expressions. For example,
print x=4
stores the value 4 into the variable `x', and then prints the value of
the assignment expression (which is 4). *Note Using GDB with Different
Languages: Languages, for more information on operators in supported
languages.
If you are not interested in seeing the value of the assignment, use
the `set' command instead of the `print' command. `set' is really the
same as `print' except that the expression's value is not printed and
is not put in the value history (*note Value history: Value History.).
The expression is evaluated only for its effects.
If the beginning of the argument string of the `set' command appears
identical to a `set' subcommand, use the `set variable' command instead
of just `set'. This command is identical to `set' except for its lack
of subcommands. For example, if your program has a variable `width',
you get an error if you try to set a new value with just `set
width=13', because GDB has the command `set width':
(gdb) whatis width
type = double
(gdb) p width
$4 = 13
(gdb) set width=47
Invalid syntax in expression.
The invalid expression, of course, is `=47'. In order to actually set
the program's variable `width', use
(gdb) set var width=47
Because the `set' command has many subcommands that can conflict
with the names of program variables, it is a good idea to use the `set
variable' command instead of just `set'. For example, if your program
has a variable `g', you run into problems if you try to set a new value
with just `set g=4', because GDB has the command `set gnutarget',
abbreviated `set g':
(gdb) whatis g
type = double
(gdb) p g
$1 = 1
(gdb) set g=4
(gdb) p g
$2 = 1
(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /home/smith/cc_progs/a.out
"/home/smith/cc_progs/a.out": can't open to read symbols:
Invalid bfd target.
(gdb) show g
The current BFD target is "=4".
The program variable `g' did not change, and you silently set the
`gnutarget' to an invalid value. In order to set the variable `g', use
(gdb) set var g=4
GDB allows more implicit conversions in assignments than C; you can
freely store an integer value into a pointer variable or vice versa,
and you can convert any structure to any other structure that is the
same length or shorter.
To store values into arbitrary places in memory, use the `{...}'
construct to generate a value of specified type at a specified address
(*note Expressions: Expressions.). For example, `{int}0x83040' refers
to memory location `0x83040' as an integer (which implies a certain size
and representation in memory), and
set {int}0x83040 = 4
stores the value 4 into that memory location.
File: gdb.info, Node: Jumping, Next: Signaling, Prev: Assignment, Up: Altering
Continuing at a different address
=================================
Ordinarily, when you continue your program, you do so at the place where
it stopped, with the `continue' command. You can instead continue at
an address of your own choosing, with the following commands:
`jump LINESPEC'
Resume execution at line LINESPEC. Execution stops again
immediately if there is a breakpoint there. *Note Printing source
lines: List, for a description of the different forms of LINESPEC.
It is common practice to use the `tbreak' command in conjunction
with `jump'. *Note Setting breakpoints: Set Breaks.
The `jump' command does not change the current stack frame, or the
stack pointer, or the contents of any memory location or any
register other than the program counter. If line LINESPEC is in a
different function from the one currently executing, the results
may be bizarre if the two functions expect different patterns of
arguments or of local variables. For this reason, the `jump'
command requests confirmation if the specified line is not in the
function currently executing. However, even bizarre results are
predictable if you are well acquainted with the machine-language
code of your program.
`jump *ADDRESS'
Resume execution at the instruction at address ADDRESS.
On many systems, you can get much the same effect as the `jump'
command by storing a new value into the register `$pc'. The difference
is that this does not start your program running; it only changes the
address of where it _will_ run when you continue. For example,
set $pc = 0x485
makes the next `continue' command or stepping command execute at
address `0x485', rather than at the address where your program stopped.
*Note Continuing and stepping: Continuing and Stepping.
The most common occasion to use the `jump' command is to back
up--perhaps with more breakpoints set--over a portion of a program that
has already executed, in order to examine its execution in more detail.
File: gdb.info, Node: Signaling, Next: Returning, Prev: Jumping, Up: Altering
Giving your program a signal
============================
`signal SIGNAL'
Resume execution where your program stopped, but immediately give
it the signal SIGNAL. SIGNAL can be the name or the number of a
signal. For example, on many systems `signal 2' and `signal
SIGINT' are both ways of sending an interrupt signal.
Alternatively, if SIGNAL is zero, continue execution without
giving a signal. This is useful when your program stopped on
account of a signal and would ordinary see the signal when resumed
with the `continue' command; `signal 0' causes it to resume
without a signal.
`signal' does not repeat when you press <RET> a second time after
executing the command.
Invoking the `signal' command is not the same as invoking the `kill'
utility from the shell. Sending a signal with `kill' causes GDB to
decide what to do with the signal depending on the signal handling
tables (*note Signals::). The `signal' command passes the signal
directly to your program.
File: gdb.info, Node: Returning, Next: Calling, Prev: Signaling, Up: Altering
Returning from a function
=========================
`return'
`return EXPRESSION'
You can cancel execution of a function call with the `return'
command. If you give an EXPRESSION argument, its value is used as
the function's return value.
When you use `return', GDB discards the selected stack frame (and
all frames within it). You can think of this as making the discarded
frame return prematurely. If you wish to specify a value to be
returned, give that value as the argument to `return'.
This pops the selected stack frame (*note Selecting a frame:
Selection.), and any other frames inside of it, leaving its caller as
the innermost remaining frame. That frame becomes selected. The
specified value is stored in the registers used for returning values of
functions.
The `return' command does not resume execution; it leaves the
program stopped in the state that would exist if the function had just
returned. In contrast, the `finish' command (*note Continuing and
stepping: Continuing and Stepping.) resumes execution until the
selected stack frame returns naturally.
File: gdb.info, Node: Calling, Next: Patching, Prev: Returning, Up: Altering
Calling program functions
=========================
`call EXPR'
Evaluate the expression EXPR without displaying `void' returned
values.
You can use this variant of the `print' command if you want to
execute a function from your program, but without cluttering the output
with `void' returned values. If the result is not void, it is printed
and saved in the value history.
File: gdb.info, Node: Patching, Prev: Calling, Up: Altering
Patching programs
=================
By default, GDB opens the file containing your program's executable
code (or the corefile) read-only. This prevents accidental alterations
to machine code; but it also prevents you from intentionally patching
your program's binary.
If you'd like to be able to patch the binary, you can specify that
explicitly with the `set write' command. For example, you might want
to turn on internal debugging flags, or even to make emergency repairs.
`set write on'
`set write off'
If you specify `set write on', GDB opens executable and core files
for both reading and writing; if you specify `set write off' (the
default), GDB opens them read-only.
If you have already loaded a file, you must load it again (using
the `exec-file' or `core-file' command) after changing `set
write', for your new setting to take effect.
`show write'
Display whether executable files and core files are opened for
writing as well as reading.
File: gdb.info, Node: GDB Files, Next: Targets, Prev: Altering, Up: Top
GDB Files
*********
GDB needs to know the file name of the program to be debugged, both in
order to read its symbol table and in order to start your program. To
debug a core dump of a previous run, you must also tell GDB the name of
the core dump file.
* Menu:
* Files:: Commands to specify files
* Separate Debug Files:: Debugging information in separate files
* Symbol Errors:: Errors reading symbol files
File: gdb.info, Node: Files, Next: Separate Debug Files, Up: GDB Files
Commands to specify files
=========================
You may want to specify executable and core dump file names. The usual
way to do this is at start-up time, using the arguments to GDB's
start-up commands (*note Getting In and Out of GDB: Invocation.).
Occasionally it is necessary to change to a different file during a
GDB session. Or you may run GDB and forget to specify a file you want
to use. In these situations the GDB commands to specify new files are
useful.
`file FILENAME'
Use FILENAME as the program to be debugged. It is read for its
symbols and for the contents of pure memory. It is also the
program executed when you use the `run' command. If you do not
specify a directory and the file is not found in the GDB working
directory, GDB uses the environment variable `PATH' as a list of
directories to search, just as the shell does when looking for a
program to run. You can change the value of this variable, for
both GDB and your program, using the `path' command.
On systems with memory-mapped files, an auxiliary file named
`FILENAME.syms' may hold symbol table information for FILENAME.
If so, GDB maps in the symbol table from `FILENAME.syms', starting
up more quickly. See the descriptions of the file options
`-mapped' and `-readnow' (available on the command line, and with
the commands `file', `symbol-file', or `add-symbol-file',
described below), for more information.
`file'
`file' with no argument makes GDB discard any information it has
on both executable file and the symbol table.
`exec-file [ FILENAME ]'
Specify that the program to be run (but not the symbol table) is
found in FILENAME. GDB searches the environment variable `PATH'
if necessary to locate your program. Omitting FILENAME means to
discard information on the executable file.
`symbol-file [ FILENAME ]'
Read symbol table information from file FILENAME. `PATH' is
searched when necessary. Use the `file' command to get both symbol
table and program to run from the same file.
`symbol-file' with no argument clears out GDB information on your
program's symbol table.
The `symbol-file' command causes GDB to forget the contents of its
convenience variables, the value history, and all breakpoints and
auto-display expressions. This is because they may contain
pointers to the internal data recording symbols and data types,
which are part of the old symbol table data being discarded inside
GDB.
`symbol-file' does not repeat if you press <RET> again after
executing it once.
When GDB is configured for a particular environment, it
understands debugging information in whatever format is the
standard generated for that environment; you may use either a GNU
compiler, or other compilers that adhere to the local conventions.
Best results are usually obtained from GNU compilers; for example,
using `gcc' you can generate debugging information for optimized
code.
For most kinds of object files, with the exception of old SVR3
systems using COFF, the `symbol-file' command does not normally
read the symbol table in full right away. Instead, it scans the
symbol table quickly to find which source files and which symbols
are present. The details are read later, one source file at a
time, as they are needed.
The purpose of this two-stage reading strategy is to make GDB
start up faster. For the most part, it is invisible except for
occasional pauses while the symbol table details for a particular
source file are being read. (The `set verbose' command can turn
these pauses into messages if desired. *Note Optional warnings
and messages: Messages/Warnings.)
We have not implemented the two-stage strategy for COFF yet. When
the symbol table is stored in COFF format, `symbol-file' reads the
symbol table data in full right away. Note that "stabs-in-COFF"
still does the two-stage strategy, since the debug info is actually
in stabs format.
`symbol-file FILENAME [ -readnow ] [ -mapped ]'
`file FILENAME [ -readnow ] [ -mapped ]'
You can override the GDB two-stage strategy for reading symbol
tables by using the `-readnow' option with any of the commands that
load symbol table information, if you want to be sure GDB has the
entire symbol table available.
If memory-mapped files are available on your system through the
`mmap' system call, you can use another option, `-mapped', to
cause GDB to write the symbols for your program into a reusable
file. Future GDB debugging sessions map in symbol information
from this auxiliary symbol file (if the program has not changed),
rather than spending time reading the symbol table from the
executable program. Using the `-mapped' option has the same
effect as starting GDB with the `-mapped' command-line option.
You can use both options together, to make sure the auxiliary
symbol file has all the symbol information for your program.
The auxiliary symbol file for a program called MYPROG is called
`MYPROG.syms'. Once this file exists (so long as it is newer than
the corresponding executable), GDB always attempts to use it when
you debug MYPROG; no special options or commands are needed.
The `.syms' file is specific to the host machine where you run
GDB. It holds an exact image of the internal GDB symbol table.
It cannot be shared across multiple host platforms.
`core-file [ FILENAME ]'
Specify the whereabouts of a core dump file to be used as the
"contents of memory". Traditionally, core files contain only some
parts of the address space of the process that generated them; GDB
can access the executable file itself for other parts.
`core-file' with no argument specifies that no core file is to be
used.
Note that the core file is ignored when your program is actually
running under GDB. So, if you have been running your program and
you wish to debug a core file instead, you must kill the
subprocess in which the program is running. To do this, use the
`kill' command (*note Killing the child process: Kill Process.).
`add-symbol-file FILENAME ADDRESS'
`add-symbol-file FILENAME ADDRESS [ -readnow ] [ -mapped ]'
`add-symbol-file FILENAME -sSECTION ADDRESS ...'
The `add-symbol-file' command reads additional symbol table
information from the file FILENAME. You would use this command
when FILENAME has been dynamically loaded (by some other means)
into the program that is running. ADDRESS should be the memory
address at which the file has been loaded; GDB cannot figure this
out for itself. You can additionally specify an arbitrary number
of `-sSECTION ADDRESS' pairs, to give an explicit section name and
base address for that section. You can specify any ADDRESS as an
expression.
The symbol table of the file FILENAME is added to the symbol table
originally read with the `symbol-file' command. You can use the
`add-symbol-file' command any number of times; the new symbol data
thus read keeps adding to the old. To discard all old symbol data
instead, use the `symbol-file' command without any arguments.
Although FILENAME is typically a shared library file, an
executable file, or some other object file which has been fully
relocated for loading into a process, you can also load symbolic
information from relocatable `.o' files, as long as:
* the file's symbolic information refers only to linker symbols
defined in that file, not to symbols defined by other object
files,
* every section the file's symbolic information refers to has
actually been loaded into the inferior, as it appears in the
file, and
* you can determine the address at which every section was
loaded, and provide these to the `add-symbol-file' command.
Some embedded operating systems, like Sun Chorus and VxWorks, can
load relocatable files into an already running program; such
systems typically make the requirements above easy to meet.
However, it's important to recognize that many native systems use
complex link procedures (`.linkonce' section factoring and C++
constructor table assembly, for example) that make the
requirements difficult to meet. In general, one cannot assume
that using `add-symbol-file' to read a relocatable object file's
symbolic information will have the same effect as linking the
relocatable object file into the program in the normal way.
`add-symbol-file' does not repeat if you press <RET> after using
it.
You can use the `-mapped' and `-readnow' options just as with the
`symbol-file' command, to change how GDB manages the symbol table
information for FILENAME.
`add-shared-symbol-file'
The `add-shared-symbol-file' command can be used only under
Harris' CXUX operating system for the Motorola 88k. GDB
automatically looks for shared libraries, however if GDB does not
find yours, you can run `add-shared-symbol-file'. It takes no
arguments.
`section'
The `section' command changes the base address of section SECTION
of the exec file to ADDR. This can be used if the exec file does
not contain section addresses, (such as in the a.out format), or
when the addresses specified in the file itself are wrong. Each
section must be changed separately. The `info files' command,
described below, lists all the sections and their addresses.
`info files'
`info target'
`info files' and `info target' are synonymous; both print the
current target (*note Specifying a Debugging Target: Targets.),
including the names of the executable and core dump files
currently in use by GDB, and the files from which symbols were
loaded. The command `help target' lists all possible targets
rather than current ones.
`maint info sections'
Another command that can give you extra information about program
sections is `maint info sections'. In addition to the section
information displayed by `info files', this command displays the
flags and file offset of each section in the executable and core
dump files. In addition, `maint info sections' provides the
following command options (which may be arbitrarily combined):
`ALLOBJ'
Display sections for all loaded object files, including
shared libraries.
`SECTIONS'
Display info only for named SECTIONS.
`SECTION-FLAGS'
Display info only for sections for which SECTION-FLAGS are
true. The section flags that GDB currently knows about are:
`ALLOC'
Section will have space allocated in the process when
loaded. Set for all sections except those containing
debug information.
`LOAD'
Section will be loaded from the file into the child
process memory. Set for pre-initialized code and data,
clear for `.bss' sections.
`RELOC'
Section needs to be relocated before loading.
`READONLY'
Section cannot be modified by the child process.
`CODE'
Section contains executable code only.
`DATA'
Section contains data only (no executable code).
`ROM'
Section will reside in ROM.
`CONSTRUCTOR'
Section contains data for constructor/destructor lists.
`HAS_CONTENTS'
Section is not empty.
`NEVER_LOAD'
An instruction to the linker to not output the section.
`COFF_SHARED_LIBRARY'
A notification to the linker that the section contains
COFF shared library information.
`IS_COMMON'
Section contains common symbols.
`set trust-readonly-sections on'
Tell GDB that readonly sections in your object file really are
read-only (i.e. that their contents will not change). In that
case, GDB can fetch values from these sections out of the object
file, rather than from the target program. For some targets
(notably embedded ones), this can be a significant enhancement to
debugging performance.
The default is off.
`set trust-readonly-sections off'
Tell GDB not to trust readonly sections. This means that the
contents of the section might change while the program is running,
and must therefore be fetched from the target when needed.
All file-specifying commands allow both absolute and relative file
names as arguments. GDB always converts the file name to an absolute
file name and remembers it that way.
GDB supports HP-UX, SunOS, SVr4, Irix 5, and IBM RS/6000 shared
libraries.
GDB automatically loads symbol definitions from shared libraries
when you use the `run' command, or when you examine a core file.
(Before you issue the `run' command, GDB does not understand references
to a function in a shared library, however--unless you are debugging a
core file).
On HP-UX, if the program loads a library explicitly, GDB
automatically loads the symbols at the time of the `shl_load' call.
There are times, however, when you may wish to not automatically load
symbol definitions from shared libraries, such as when they are
particularly large or there are many of them.
To control the automatic loading of shared library symbols, use the
commands:
`set auto-solib-add MODE'
If MODE is `on', symbols from all shared object libraries will be
loaded automatically when the inferior begins execution, you
attach to an independently started inferior, or when the dynamic
linker informs GDB that a new library has been loaded. If MODE is
`off', symbols must be loaded manually, using the `sharedlibrary'
command. The default value is `on'.
`show auto-solib-add'
Display the current autoloading mode.
To explicitly load shared library symbols, use the `sharedlibrary'
command:
`info share'
`info sharedlibrary'
Print the names of the shared libraries which are currently loaded.
`sharedlibrary REGEX'
`share REGEX'
Load shared object library symbols for files matching a Unix
regular expression. As with files loaded automatically, it only
loads shared libraries required by your program for a core file or
after typing `run'. If REGEX is omitted all shared libraries
required by your program are loaded.
On some systems, such as HP-UX systems, GDB supports autoloading
shared library symbols until a limiting threshold size is reached.
This provides the benefit of allowing autoloading to remain on by
default, but avoids autoloading excessively large shared libraries, up
to a threshold that is initially set, but which you can modify if you
wish.
Beyond that threshold, symbols from shared libraries must be
explicitly loaded. To load these symbols, use the command
`sharedlibrary FILENAME'. The base address of the shared library is
determined automatically by GDB and need not be specified.
To display or set the threshold, use the commands:
`set auto-solib-limit THRESHOLD'
Set the autoloading size threshold, in an integral number of
megabytes. If THRESHOLD is nonzero and shared library autoloading
is enabled, symbols from all shared object libraries will be
loaded until the total size of the loaded shared library symbols
exceeds this threshold. Otherwise, symbols must be loaded
manually, using the `sharedlibrary' command. The default
threshold is 100 (i.e. 100 Mb).
`show auto-solib-limit'
Display the current autoloading size threshold, in megabytes.
Shared libraries are also supported in many cross or remote debugging
configurations. A copy of the target's libraries need to be present on
the host system; they need to be the same as the target libraries,
although the copies on the target can be stripped as long as the copies
on the host are not.
You need to tell GDB where the target libraries are, so that it can
load the correct copies--otherwise, it may try to load the host's
libraries. GDB has two variables to specify the search directories for
target libraries.
`set solib-absolute-prefix PATH'
If this variable is set, PATH will be used as a prefix for any
absolute shared library paths; many runtime loaders store the
absolute paths to the shared library in the target program's
memory. If you use `solib-absolute-prefix' to find shared
libraries, they need to be laid out in the same way that they are
on the target, with e.g. a `/usr/lib' hierarchy under PATH.
You can set the default value of `solib-absolute-prefix' by using
the configure-time `--with-sysroot' option.
`show solib-absolute-prefix'
Display the current shared library prefix.
`set solib-search-path PATH'
If this variable is set, PATH is a colon-separated list of
directories to search for shared libraries. `solib-search-path'
is used after `solib-absolute-prefix' fails to locate the library,
or if the path to the library is relative instead of absolute. If
you want to use `solib-search-path' instead of
`solib-absolute-prefix', be sure to set `solib-absolute-prefix' to
a nonexistant directory to prevent GDB from finding your host's
libraries.
`show solib-search-path'
Display the current shared library search path.
File: gdb.info, Node: Separate Debug Files, Next: Symbol Errors, Prev: Files, Up: GDB Files
Debugging Information in Separate Files
=======================================
GDB allows you to put a program's debugging information in a file
separate from the executable itself, in a way that allows GDB to find
and load the debugging information automatically. Since debugging
information can be very large -- sometimes larger than the executable
code itself -- some systems distribute debugging information for their
executables in separate files, which users can install only when they
need to debug a problem.
If an executable's debugging information has been extracted to a
separate file, the executable should contain a "debug link" giving the
name of the debugging information file (with no directory components),
and a checksum of its contents. (The exact form of a debug link is
described below.) If the full name of the directory containing the
executable is EXECDIR, and the executable has a debug link that
specifies the name DEBUGFILE, then GDB will automatically search for
the debugging information file in three places:
* the directory containing the executable file (that is, it will look
for a file named `EXECDIR/DEBUGFILE',
* a subdirectory of that directory named `.debug' (that is, the file
`EXECDIR/.debug/DEBUGFILE', and
* a subdirectory of the global debug file directory that includes the
executable's full path, and the name from the link (that is, the
file `GLOBALDEBUGDIR/EXECDIR/DEBUGFILE', where GLOBALDEBUGDIR is
the global debug file directory, and EXECDIR has been turned into
a relative path).
GDB checks under each of these names for a debugging information file
whose checksum matches that given in the link, and reads the debugging
information from the first one it finds.
So, for example, if you ask GDB to debug `/usr/bin/ls', which has a
link containing the name `ls.debug', and the global debug directory is
`/usr/lib/debug', then GDB will look for debug information in
`/usr/bin/ls.debug', `/usr/bin/.debug/ls.debug', and
`/usr/lib/debug/usr/bin/ls.debug'.
You can set the global debugging info directory's name, and view the
name GDB is currently using.
`set debug-file-directory DIRECTORY'
Set the directory which GDB searches for separate debugging
information files to DIRECTORY.
`show debug-file-directory'
Show the directory GDB searches for separate debugging information
files.
A debug link is a special section of the executable file named
`.gnu_debuglink'. The section must contain:
* A filename, with any leading directory components removed,
followed by a zero byte,
* zero to three bytes of padding, as needed to reach the next
four-byte boundary within the section, and
* a four-byte CRC checksum, stored in the same endianness used for
the executable file itself. The checksum is computed on the
debugging information file's full contents by the function given
below, passing zero as the CRC argument.
Any executable file format can carry a debug link, as long as it can
contain a section named `.gnu_debuglink' with the contents described
above.
The debugging information file itself should be an ordinary
executable, containing a full set of linker symbols, sections, and
debugging information. The sections of the debugging information file
should have the same names, addresses and sizes as the original file,
but they need not contain any data -- much like a `.bss' section in an
ordinary executable.
As of December 2002, there is no standard GNU utility to produce
separated executable / debugging information file pairs. Ulrich
Drepper's `elfutils' package, starting with version 0.53, contains a
version of the `strip' command such that the command `strip foo -f
foo.debug' removes the debugging information from the executable file
`foo', places it in the file `foo.debug', and leaves behind a debug
link in `foo'.
Since there are many different ways to compute CRC's (different
polynomials, reversals, byte ordering, etc.), the simplest way to
describe the CRC used in `.gnu_debuglink' sections is to give the
complete code for a function that computes it:
unsigned long
gnu_debuglink_crc32 (unsigned long crc,
unsigned char *buf, size_t len)
{
static const unsigned long crc32_table[256] =
{
0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
0x2d02ef8d
};
unsigned char *end;
crc = ~crc & 0xffffffff;
for (end = buf + len; buf < end; ++buf)
crc = crc32_table[(crc ^ *buf) & 0xff] ^ (crc >> 8);
return ~crc & 0xffffffff;
}
File: gdb.info, Node: Symbol Errors, Prev: Separate Debug Files, Up: GDB Files
Errors reading symbol files
===========================
While reading a symbol file, GDB occasionally encounters problems, such
as symbol types it does not recognize, or known bugs in compiler
output. By default, GDB does not notify you of such problems, since
they are relatively common and primarily of interest to people
debugging compilers. If you are interested in seeing information about
ill-constructed symbol tables, you can either ask GDB to print only one
message about each such type of problem, no matter how many times the
problem occurs; or you can ask GDB to print more messages, to see how
many times the problems occur, with the `set complaints' command (*note
Optional warnings and messages: Messages/Warnings.).
The messages currently printed, and their meanings, include:
`inner block not inside outer block in SYMBOL'
The symbol information shows where symbol scopes begin and end
(such as at the start of a function or a block of statements).
This error indicates that an inner scope block is not fully
contained in its outer scope blocks.
GDB circumvents the problem by treating the inner block as if it
had the same scope as the outer block. In the error message,
SYMBOL may be shown as "`(don't know)'" if the outer block is not a
function.
`block at ADDRESS out of order'
The symbol information for symbol scope blocks should occur in
order of increasing addresses. This error indicates that it does
not do so.
GDB does not circumvent this problem, and has trouble locating
symbols in the source file whose symbols it is reading. (You can
often determine what source file is affected by specifying `set
verbose on'. *Note Optional warnings and messages:
Messages/Warnings.)
`bad block start address patched'
The symbol information for a symbol scope block has a start address
smaller than the address of the preceding source line. This is
known to occur in the SunOS 4.1.1 (and earlier) C compiler.
GDB circumvents the problem by treating the symbol scope block as
starting on the previous source line.
`bad string table offset in symbol N'
Symbol number N contains a pointer into the string table which is
larger than the size of the string table.
GDB circumvents the problem by considering the symbol to have the
name `foo', which may cause other problems if many symbols end up
with this name.
`unknown symbol type `0xNN''
The symbol information contains new data types that GDB does not
yet know how to read. `0xNN' is the symbol type of the
uncomprehended information, in hexadecimal.
GDB circumvents the error by ignoring this symbol information.
This usually allows you to debug your program, though certain
symbols are not accessible. If you encounter such a problem and
feel like debugging it, you can debug `gdb' with itself, breakpoint
on `complain', then go up to the function `read_dbx_symtab' and
examine `*bufp' to see the symbol.
`stub type has NULL name'
GDB could not find the full definition for a struct or class.
`const/volatile indicator missing (ok if using g++ v1.x), got...'
The symbol information for a C++ member function is missing some
information that recent versions of the compiler should have
output for it.
`info mismatch between compiler and debugger'
GDB could not parse a type specification output by the compiler.
File: gdb.info, Node: Targets, Next: Remote Debugging, Prev: GDB Files, Up: Top
Specifying a Debugging Target
*****************************
A "target" is the execution environment occupied by your program.
Often, GDB runs in the same host environment as your program; in
that case, the debugging target is specified as a side effect when you
use the `file' or `core' commands. When you need more flexibility--for
example, running GDB on a physically separate host, or controlling a
standalone system over a serial port or a realtime system over a TCP/IP
connection--you can use the `target' command to specify one of the
target types configured for GDB (*note Commands for managing targets:
Target Commands.).
* Menu:
* Active Targets:: Active targets
* Target Commands:: Commands for managing targets
* Byte Order:: Choosing target byte order
* Remote:: Remote debugging
* KOD:: Kernel Object Display
File: gdb.info, Node: Active Targets, Next: Target Commands, Up: Targets
Active targets
==============
There are three classes of targets: processes, core files, and
executable files. GDB can work concurrently on up to three active
targets, one in each class. This allows you to (for example) start a
process and inspect its activity without abandoning your work on a core
file.
For example, if you execute `gdb a.out', then the executable file
`a.out' is the only active target. If you designate a core file as
well--presumably from a prior run that crashed and coredumped--then GDB
has two active targets and uses them in tandem, looking first in the
corefile target, then in the executable file, to satisfy requests for
memory addresses. (Typically, these two classes of target are
complementary, since core files contain only a program's read-write
memory--variables and so on--plus machine status, while executable
files contain only the program text and initialized data.)
When you type `run', your executable file becomes an active process
target as well. When a process target is active, all GDB commands
requesting memory addresses refer to that target; addresses in an
active core file or executable file target are obscured while the
process target is active.
Use the `core-file' and `exec-file' commands to select a new core
file or executable target (*note Commands to specify files: Files.).
To specify as a target a process that is already running, use the
`attach' command (*note Debugging an already-running process: Attach.).
File: gdb.info, Node: Target Commands, Next: Byte Order, Prev: Active Targets, Up: Targets
Commands for managing targets
=============================
`target TYPE PARAMETERS'
Connects the GDB host environment to a target machine or process.
A target is typically a protocol for talking to debugging
facilities. You use the argument TYPE to specify the type or
protocol of the target machine.
Further PARAMETERS are interpreted by the target protocol, but
typically include things like device names or host names to connect
with, process numbers, and baud rates.
The `target' command does not repeat if you press <RET> again
after executing the command.
`help target'
Displays the names of all targets available. To display targets
currently selected, use either `info target' or `info files'
(*note Commands to specify files: Files.).
`help target NAME'
Describe a particular target, including any parameters necessary to
select it.
`set gnutarget ARGS'
GDB uses its own library BFD to read your files. GDB knows
whether it is reading an "executable", a "core", or a ".o" file;
however, you can specify the file format with the `set gnutarget'
command. Unlike most `target' commands, with `gnutarget' the
`target' refers to a program, not a machine.
_Warning:_ To specify a file format with `set gnutarget', you
must know the actual BFD name.
*Note Commands to specify files: Files.
`show gnutarget'
Use the `show gnutarget' command to display what file format
`gnutarget' is set to read. If you have not set `gnutarget', GDB
will determine the file format for each file automatically, and
`show gnutarget' displays `The current BDF target is "auto"'.
Here are some common targets (available, or not, depending on the GDB
configuration):
`target exec PROGRAM'
An executable file. `target exec PROGRAM' is the same as
`exec-file PROGRAM'.
`target core FILENAME'
A core dump file. `target core FILENAME' is the same as
`core-file FILENAME'.
`target remote DEV'
Remote serial target in GDB-specific protocol. The argument DEV
specifies what serial device to use for the connection (e.g.
`/dev/ttya'). *Note Remote debugging: Remote. `target remote'
supports the `load' command. This is only useful if you have some
other way of getting the stub to the target system, and you can put
it somewhere in memory where it won't get clobbered by the
download.
`target sim'
Builtin CPU simulator. GDB includes simulators for most
architectures. In general,
target sim
load
run
works; however, you cannot assume that a specific memory map,
device drivers, or even basic I/O is available, although some
simulators do provide these. For info about any
processor-specific simulator details, see the appropriate section
in *Note Embedded Processors: Embedded Processors.
Some configurations may include these targets as well:
`target nrom DEV'
NetROM ROM emulator. This target only supports downloading.
Different targets are available on different configurations of GDB;
your configuration may have more or fewer targets.
Many remote targets require you to download the executable's code
once you've successfully established a connection.
`load FILENAME'
Depending on what remote debugging facilities are configured into
GDB, the `load' command may be available. Where it exists, it is
meant to make FILENAME (an executable) available for debugging on
the remote system--by downloading, or dynamic linking, for example.
`load' also records the FILENAME symbol table in GDB, like the
`add-symbol-file' command.
If your GDB does not have a `load' command, attempting to execute
it gets the error message "`You can't do that when your target is
...'"
The file is loaded at whatever address is specified in the
executable. For some object file formats, you can specify the
load address when you link the program; for other formats, like
a.out, the object file format specifies a fixed address.
`load' does not repeat if you press <RET> again after using it.
File: gdb.info, Node: Byte Order, Next: Remote, Prev: Target Commands, Up: Targets
Choosing target byte order
==========================
Some types of processors, such as the MIPS, PowerPC, and Renesas SH,
offer the ability to run either big-endian or little-endian byte
orders. Usually the executable or symbol will include a bit to
designate the endian-ness, and you will not need to worry about which
to use. However, you may still find it useful to adjust GDB's idea of
processor endian-ness manually.
`set endian big'
Instruct GDB to assume the target is big-endian.
`set endian little'
Instruct GDB to assume the target is little-endian.
`set endian auto'
Instruct GDB to use the byte order associated with the executable.
`show endian'
Display GDB's current idea of the target byte order.
Note that these commands merely adjust interpretation of symbolic
data on the host, and that they have absolutely no effect on the target
system.
File: gdb.info, Node: Remote, Next: KOD, Prev: Byte Order, Up: Targets
Remote debugging
================
If you are trying to debug a program running on a machine that cannot
run GDB in the usual way, it is often useful to use remote debugging.
For example, you might use remote debugging on an operating system
kernel, or on a small system which does not have a general purpose
operating system powerful enough to run a full-featured debugger.
Some configurations of GDB have special serial or TCP/IP interfaces
to make this work with particular debugging targets. In addition, GDB
comes with a generic serial protocol (specific to GDB, but not specific
to any particular target system) which you can use if you write the
remote stubs--the code that runs on the remote system to communicate
with GDB.
Other remote targets may be available in your configuration of GDB;
use `help target' to list them.
File: gdb.info, Node: KOD, Prev: Remote, Up: Targets
Kernel Object Display
=====================
Some targets support kernel object display. Using this facility, GDB
communicates specially with the underlying operating system and can
display information about operating system-level objects such as
mutexes and other synchronization objects. Exactly which objects can be
displayed is determined on a per-OS basis.
Use the `set os' command to set the operating system. This tells
GDB which kernel object display module to initialize:
(gdb) set os cisco
The associated command `show os' displays the operating system set
with the `set os' command; if no operating system has been set, `show
os' will display an empty string `""'.
If `set os' succeeds, GDB will display some information about the
operating system, and will create a new `info' command which can be
used to query the target. The `info' command is named after the
operating system:
(gdb) info cisco
List of Cisco Kernel Objects
Object Description
any Any and all objects
Further subcommands can be used to query about particular objects
known by the kernel.
There is currently no way to determine whether a given operating
system is supported other than to try setting it with `set os NAME',
where NAME is the name of the operating system you want to try.
File: gdb.info, Node: Remote Debugging, Next: Configurations, Prev: Targets, Up: Top
Debugging remote programs
*************************
* Menu:
* Connecting:: Connecting to a remote target
* Server:: Using the gdbserver program
* NetWare:: Using the gdbserve.nlm program
* Remote configuration:: Remote configuration
* remote stub:: Implementing a remote stub
File: gdb.info, Node: Connecting, Next: Server, Up: Remote Debugging
Connecting to a remote target
=============================
On the GDB host machine, you will need an unstripped copy of your
program, since GDB needs symobl and debugging information. Start up
GDB as usual, using the name of the local copy of your program as the
first argument.
If you're using a serial line, you may want to give GDB the `--baud'
option, or use the `set remotebaud' command before the `target' command.
After that, use `target remote' to establish communications with the
target machine. Its argument specifies how to communicate--either via
a devicename attached to a direct serial line, or a TCP or UDP port
(possibly to a terminal server which in turn has a serial line to the
target). For example, to use a serial line connected to the device
named `/dev/ttyb':
target remote /dev/ttyb
To use a TCP connection, use an argument of the form `HOST:PORT' or
`tcp:HOST:PORT'. For example, to connect to port 2828 on a terminal
server named `manyfarms':
target remote manyfarms:2828
If your remote target is actually running on the same machine as
your debugger session (e.g. a simulator of your target running on the
same host), you can omit the hostname. For example, to connect to port
1234 on your local machine:
target remote :1234
Note that the colon is still required here.
To use a UDP connection, use an argument of the form
`udp:HOST:PORT'. For example, to connect to UDP port 2828 on a
terminal server named `manyfarms':
target remote udp:manyfarms:2828
When using a UDP connection for remote debugging, you should keep in
mind that the `U' stands for "Unreliable". UDP can silently drop
packets on busy or unreliable networks, which will cause havoc with
your debugging session.
Now you can use all the usual commands to examine and change data
and to step and continue the remote program.
Whenever GDB is waiting for the remote program, if you type the
interrupt character (often <C-C>), GDB attempts to stop the program.
This may or may not succeed, depending in part on the hardware and the
serial drivers the remote system uses. If you type the interrupt
character once again, GDB displays this prompt:
Interrupted while waiting for the program.
Give up (and stop debugging it)? (y or n)
If you type `y', GDB abandons the remote debugging session. (If you
decide you want to try again later, you can use `target remote' again
to connect once more.) If you type `n', GDB goes back to waiting.
`detach'
When you have finished debugging the remote program, you can use
the `detach' command to release it from GDB control. Detaching
from the target normally resumes its execution, but the results
will depend on your particular remote stub. After the `detach'
command, GDB is free to connect to another target.
`disconnect'
The `disconnect' command behaves like `detach', except that the
target is generally not resumed. It will wait for GDB (this
instance or another one) to connect and continue debugging. After
the `disconnect' command, GDB is again free to connect to another
target.
File: gdb.info, Node: Server, Next: NetWare, Prev: Connecting, Up: Remote Debugging
Using the `gdbserver' program
=============================
`gdbserver' is a control program for Unix-like systems, which allows
you to connect your program with a remote GDB via `target remote'--but
without linking in the usual debugging stub.
`gdbserver' is not a complete replacement for the debugging stubs,
because it requires essentially the same operating-system facilities
that GDB itself does. In fact, a system that can run `gdbserver' to
connect to a remote GDB could also run GDB locally! `gdbserver' is
sometimes useful nevertheless, because it is a much smaller program
than GDB itself. It is also easier to port than all of GDB, so you may
be able to get started more quickly on a new system by using
`gdbserver'. Finally, if you develop code for real-time systems, you
may find that the tradeoffs involved in real-time operation make it
more convenient to do as much development work as possible on another
system, for example by cross-compiling. You can use `gdbserver' to
make a similar choice for debugging.
GDB and `gdbserver' communicate via either a serial line or a TCP
connection, using the standard GDB remote serial protocol.
_On the target machine,_
you need to have a copy of the program you want to debug.
`gdbserver' does not need your program's symbol table, so you can
strip the program if necessary to save space. GDB on the host
system does all the symbol handling.
To use the server, you must tell it how to communicate with GDB;
the name of your program; and the arguments for your program. The
usual syntax is:
target> gdbserver COMM PROGRAM [ ARGS ... ]
COMM is either a device name (to use a serial line) or a TCP
hostname and portnumber. For example, to debug Emacs with the
argument `foo.txt' and communicate with GDB over the serial port
`/dev/com1':
target> gdbserver /dev/com1 emacs foo.txt
`gdbserver' waits passively for the host GDB to communicate with
it.
To use a TCP connection instead of a serial line:
target> gdbserver host:2345 emacs foo.txt
The only difference from the previous example is the first
argument, specifying that you are communicating with the host GDB
via TCP. The `host:2345' argument means that `gdbserver' is to
expect a TCP connection from machine `host' to local TCP port 2345.
(Currently, the `host' part is ignored.) You can choose any number
you want for the port number as long as it does not conflict with
any TCP ports already in use on the target system (for example,
`23' is reserved for `telnet').(1) You must use the same port
number with the host GDB `target remote' command.
On some targets, `gdbserver' can also attach to running programs.
This is accomplished via the `--attach' argument. The syntax is:
target> gdbserver COMM --attach PID
PID is the process ID of a currently running process. It isn't
necessary to point `gdbserver' at a binary for the running process.
You can debug processes by name instead of process ID if your
target has the `pidof' utility:
target> gdbserver COMM --attach `pidof PROGRAM`
In case more than one copy of PROGRAM is running, or PROGRAM has
multiple threads, most versions of `pidof' support the `-s' option
to only return the first process ID.
_On the host machine,_
connect to your target (*note Connecting to a remote target:
Connecting.). For TCP connections, you must start up `gdbserver'
prior to using the `target remote' command. Otherwise you may get
an error whose text depends on the host system, but which usually
looks something like `Connection refused'. You don't need to use
the `load' command in GDB when using gdbserver, since the program
is already on the target.
---------- Footnotes ----------
(1) If you choose a port number that conflicts with another service,
`gdbserver' prints an error message and exits.
File: gdb.info, Node: NetWare, Next: Remote configuration, Prev: Server, Up: Remote Debugging
Using the `gdbserve.nlm' program
================================
`gdbserve.nlm' is a control program for NetWare systems, which allows
you to connect your program with a remote GDB via `target remote'.
GDB and `gdbserve.nlm' communicate via a serial line, using the
standard GDB remote serial protocol.
_On the target machine,_
you need to have a copy of the program you want to debug.
`gdbserve.nlm' does not need your program's symbol table, so you
can strip the program if necessary to save space. GDB on the host
system does all the symbol handling.
To use the server, you must tell it how to communicate with GDB;
the name of your program; and the arguments for your program. The
syntax is:
load gdbserve [ BOARD=BOARD ] [ PORT=PORT ]
[ BAUD=BAUD ] PROGRAM [ ARGS ... ]
BOARD and PORT specify the serial line; BAUD specifies the baud
rate used by the connection. PORT and NODE default to 0, BAUD
defaults to 9600bps.
For example, to debug Emacs with the argument `foo.txt'and
communicate with GDB over serial port number 2 or board 1 using a
19200bps connection:
load gdbserve BOARD=1 PORT=2 BAUD=19200 emacs foo.txt
__
On the GDB host machine, connect to your target (*note Connecting
to a remote target: Connecting.).
File: gdb.info, Node: Remote configuration, Next: remote stub, Prev: NetWare, Up: Remote Debugging
Remote configuration
====================
The following configuration options are available when debugging remote
programs:
`set remote hardware-watchpoint-limit LIMIT'
`set remote hardware-breakpoint-limit LIMIT'
Restrict GDB to using LIMIT remote hardware breakpoint or
watchpoints. A limit of -1, the default, is treated as unlimited.
File: gdb.info, Node: remote stub, Prev: Remote configuration, Up: Remote Debugging
Implementing a remote stub
==========================
The stub files provided with GDB implement the target side of the
communication protocol, and the GDB side is implemented in the GDB
source file `remote.c'. Normally, you can simply allow these
subroutines to communicate, and ignore the details. (If you're
implementing your own stub file, you can still ignore the details: start
with one of the existing stub files. `sparc-stub.c' is the best
organized, and therefore the easiest to read.)
To debug a program running on another machine (the debugging
"target" machine), you must first arrange for all the usual
prerequisites for the program to run by itself. For example, for a C
program, you need:
1. A startup routine to set up the C runtime environment; these
usually have a name like `crt0'. The startup routine may be
supplied by your hardware supplier, or you may have to write your
own.
2. A C subroutine library to support your program's subroutine calls,
notably managing input and output.
3. A way of getting your program to the other machine--for example, a
download program. These are often supplied by the hardware
manufacturer, but you may have to write your own from hardware
documentation.
The next step is to arrange for your program to use a serial port to
communicate with the machine where GDB is running (the "host" machine).
In general terms, the scheme looks like this:
_On the host,_
GDB already understands how to use this protocol; when everything
else is set up, you can simply use the `target remote' command
(*note Specifying a Debugging Target: Targets.).
_On the target,_
you must link with your program a few special-purpose subroutines
that implement the GDB remote serial protocol. The file
containing these subroutines is called a "debugging stub".
On certain remote targets, you can use an auxiliary program
`gdbserver' instead of linking a stub into your program. *Note
Using the `gdbserver' program: Server, for details.
The debugging stub is specific to the architecture of the remote
machine; for example, use `sparc-stub.c' to debug programs on SPARC
boards.
These working remote stubs are distributed with GDB:
`i386-stub.c'
For Intel 386 and compatible architectures.
`m68k-stub.c'
For Motorola 680x0 architectures.
`sh-stub.c'
For Renesas SH architectures.
`sparc-stub.c'
For SPARC architectures.
`sparcl-stub.c'
For Fujitsu SPARCLITE architectures.
The `README' file in the GDB distribution may list other recently
added stubs.
* Menu:
* Stub Contents:: What the stub can do for you
* Bootstrapping:: What you must do for the stub
* Debug Session:: Putting it all together
File: gdb.info, Node: Stub Contents, Next: Bootstrapping, Up: remote stub
What the stub can do for you
----------------------------
The debugging stub for your architecture supplies these three
subroutines:
`set_debug_traps'
This routine arranges for `handle_exception' to run when your
program stops. You must call this subroutine explicitly near the
beginning of your program.
`handle_exception'
This is the central workhorse, but your program never calls it
explicitly--the setup code arranges for `handle_exception' to run
when a trap is triggered.
`handle_exception' takes control when your program stops during
execution (for example, on a breakpoint), and mediates
communications with GDB on the host machine. This is where the
communications protocol is implemented; `handle_exception' acts as
the GDB representative on the target machine. It begins by
sending summary information on the state of your program, then
continues to execute, retrieving and transmitting any information
GDB needs, until you execute a GDB command that makes your program
resume; at that point, `handle_exception' returns control to your
own code on the target machine.
`breakpoint'
Use this auxiliary subroutine to make your program contain a
breakpoint. Depending on the particular situation, this may be
the only way for GDB to get control. For instance, if your target
machine has some sort of interrupt button, you won't need to call
this; pressing the interrupt button transfers control to
`handle_exception'--in effect, to GDB. On some machines, simply
receiving characters on the serial port may also trigger a trap;
again, in that situation, you don't need to call `breakpoint' from
your own program--simply running `target remote' from the host GDB
session gets control.
Call `breakpoint' if none of these is true, or if you simply want
to make certain your program stops at a predetermined point for the
start of your debugging session.
File: gdb.info, Node: Bootstrapping, Next: Debug Session, Prev: Stub Contents, Up: remote stub
What you must do for the stub
-----------------------------
The debugging stubs that come with GDB are set up for a particular chip
architecture, but they have no information about the rest of your
debugging target machine.
First of all you need to tell the stub how to communicate with the
serial port.
`int getDebugChar()'
Write this subroutine to read a single character from the serial
port. It may be identical to `getchar' for your target system; a
different name is used to allow you to distinguish the two if you
wish.
`void putDebugChar(int)'
Write this subroutine to write a single character to the serial
port. It may be identical to `putchar' for your target system; a
different name is used to allow you to distinguish the two if you
wish.
If you want GDB to be able to stop your program while it is running,
you need to use an interrupt-driven serial driver, and arrange for it
to stop when it receives a `^C' (`\003', the control-C character).
That is the character which GDB uses to tell the remote system to stop.
Getting the debugging target to return the proper status to GDB
probably requires changes to the standard stub; one quick and dirty way
is to just execute a breakpoint instruction (the "dirty" part is that
GDB reports a `SIGTRAP' instead of a `SIGINT').
Other routines you need to supply are:
`void exceptionHandler (int EXCEPTION_NUMBER, void *EXCEPTION_ADDRESS)'
Write this function to install EXCEPTION_ADDRESS in the exception
handling tables. You need to do this because the stub does not
have any way of knowing what the exception handling tables on your
target system are like (for example, the processor's table might
be in ROM, containing entries which point to a table in RAM).
EXCEPTION_NUMBER is the exception number which should be changed;
its meaning is architecture-dependent (for example, different
numbers might represent divide by zero, misaligned access, etc).
When this exception occurs, control should be transferred directly
to EXCEPTION_ADDRESS, and the processor state (stack, registers,
and so on) should be just as it is when a processor exception
occurs. So if you want to use a jump instruction to reach
EXCEPTION_ADDRESS, it should be a simple jump, not a jump to
subroutine.
For the 386, EXCEPTION_ADDRESS should be installed as an interrupt
gate so that interrupts are masked while the handler runs. The
gate should be at privilege level 0 (the most privileged level).
The SPARC and 68k stubs are able to mask interrupts themselves
without help from `exceptionHandler'.
`void flush_i_cache()'
On SPARC and SPARCLITE only, write this subroutine to flush the
instruction cache, if any, on your target machine. If there is no
instruction cache, this subroutine may be a no-op.
On target machines that have instruction caches, GDB requires this
function to make certain that the state of your program is stable.
You must also make sure this library routine is available:
`void *memset(void *, int, int)'
This is the standard library function `memset' that sets an area of
memory to a known value. If you have one of the free versions of
`libc.a', `memset' can be found there; otherwise, you must either
obtain it from your hardware manufacturer, or write your own.
If you do not use the GNU C compiler, you may need other standard
library subroutines as well; this varies from one stub to another, but
in general the stubs are likely to use any of the common library
subroutines which `gcc' generates as inline code.
File: gdb.info, Node: Debug Session, Prev: Bootstrapping, Up: remote stub
Putting it all together
-----------------------
In summary, when your program is ready to debug, you must follow these
steps.
1. Make sure you have defined the supporting low-level routines
(*note What you must do for the stub: Bootstrapping.):
`getDebugChar', `putDebugChar',
`flush_i_cache', `memset', `exceptionHandler'.
2. Insert these lines near the top of your program:
set_debug_traps();
breakpoint();
3. For the 680x0 stub only, you need to provide a variable called
`exceptionHook'. Normally you just use:
void (*exceptionHook)() = 0;
but if before calling `set_debug_traps', you set it to point to a
function in your program, that function is called when `GDB'
continues after stopping on a trap (for example, bus error). The
function indicated by `exceptionHook' is called with one
parameter: an `int' which is the exception number.
4. Compile and link together: your program, the GDB debugging stub for
your target architecture, and the supporting subroutines.
5. Make sure you have a serial connection between your target machine
and the GDB host, and identify the serial port on the host.
6. Download your program to your target machine (or get it there by
whatever means the manufacturer provides), and start it.
7. Start GDB on the host, and connect to the target (*note Connecting
to a remote target: Connecting.).
File: gdb.info, Node: Configurations, Next: Controlling GDB, Prev: Remote Debugging, Up: Top
Configuration-Specific Information
**********************************
While nearly all GDB commands are available for all native and cross
versions of the debugger, there are some exceptions. This chapter
describes things that are only available in certain configurations.
There are three major categories of configurations: native
configurations, where the host and target are the same, embedded
operating system configurations, which are usually the same for several
different processor architectures, and bare embedded processors, which
are quite different from each other.
* Menu:
* Native::
* Embedded OS::
* Embedded Processors::
* Architectures::
File: gdb.info, Node: Native, Next: Embedded OS, Up: Configurations
Native
======
This section describes details specific to particular native
configurations.
* Menu:
* HP-UX:: HP-UX
* SVR4 Process Information:: SVR4 process information
* DJGPP Native:: Features specific to the DJGPP port
* Cygwin Native:: Features specific to the Cygwin port
File: gdb.info, Node: HP-UX, Next: SVR4 Process Information, Up: Native
HP-UX
-----
On HP-UX systems, if you refer to a function or variable name that
begins with a dollar sign, GDB searches for a user or system name
first, before it searches for a convenience variable.
File: gdb.info, Node: SVR4 Process Information, Next: DJGPP Native, Prev: HP-UX, Up: Native
SVR4 process information
------------------------
Many versions of SVR4 provide a facility called `/proc' that can be
used to examine the image of a running process using file-system
subroutines. If GDB is configured for an operating system with this
facility, the command `info proc' is available to report on several
kinds of information about the process running your program. `info
proc' works only on SVR4 systems that include the `procfs' code. This
includes OSF/1 (Digital Unix), Solaris, Irix, and Unixware, but not
HP-UX or GNU/Linux, for example.
`info proc'
Summarize available information about the process.
`info proc mappings'
Report on the address ranges accessible in the program, with
information on whether your program may read, write, or execute
each range.
File: gdb.info, Node: DJGPP Native, Next: Cygwin Native, Prev: SVR4 Process Information, Up: Native
Features for Debugging DJGPP Programs
-------------------------------------
DJGPP is the port of GNU development tools to MS-DOS and MS-Windows.
DJGPP programs are 32-bit protected-mode programs that use the "DPMI"
(DOS Protected-Mode Interface) API to run on top of real-mode DOS
systems and their emulations.
GDB supports native debugging of DJGPP programs, and defines a few
commands specific to the DJGPP port. This subsection describes those
commands.
`info dos'
This is a prefix of DJGPP-specific commands which print
information about the target system and important OS structures.
`info dos sysinfo'
This command displays assorted information about the underlying
platform: the CPU type and features, the OS version and flavor, the
DPMI version, and the available conventional and DPMI memory.
`info dos gdt'
`info dos ldt'
`info dos idt'
These 3 commands display entries from, respectively, Global, Local,
and Interrupt Descriptor Tables (GDT, LDT, and IDT). The
descriptor tables are data structures which store a descriptor for
each segment that is currently in use. The segment's selector is
an index into a descriptor table; the table entry for that index
holds the descriptor's base address and limit, and its attributes
and access rights.
A typical DJGPP program uses 3 segments: a code segment, a data
segment (used for both data and the stack), and a DOS segment
(which allows access to DOS/BIOS data structures and absolute
addresses in conventional memory). However, the DPMI host will
usually define additional segments in order to support the DPMI
environment.
These commands allow to display entries from the descriptor tables.
Without an argument, all entries from the specified table are
displayed. An argument, which should be an integer expression,
means display a single entry whose index is given by the argument.
For example, here's a convenient way to display information about
the debugged program's data segment:
`(gdb) info dos ldt $ds'
`0x13f: base=0x11970000 limit=0x0009ffff 32-Bit Data (Read/Write, Exp-up)'
This comes in handy when you want to see whether a pointer is
outside the data segment's limit (i.e. "garbled").
`info dos pde'
`info dos pte'
These two commands display entries from, respectively, the Page
Directory and the Page Tables. Page Directories and Page Tables
are data structures which control how virtual memory addresses are
mapped into physical addresses. A Page Table includes an entry
for every page of memory that is mapped into the program's address
space; there may be several Page Tables, each one holding up to
4096 entries. A Page Directory has up to 4096 entries, one each
for every Page Table that is currently in use.
Without an argument, `info dos pde' displays the entire Page
Directory, and `info dos pte' displays all the entries in all of
the Page Tables. An argument, an integer expression, given to the
`info dos pde' command means display only that entry from the Page
Directory table. An argument given to the `info dos pte' command
means display entries from a single Page Table, the one pointed to
by the specified entry in the Page Directory.
These commands are useful when your program uses "DMA" (Direct
Memory Access), which needs physical addresses to program the DMA
controller.
These commands are supported only with some DPMI servers.
`info dos address-pte ADDR'
This command displays the Page Table entry for a specified linear
address. The argument linear address ADDR should already have the
appropriate segment's base address added to it, because this
command accepts addresses which may belong to _any_ segment. For
example, here's how to display the Page Table entry for the page
where the variable `i' is stored:
`(gdb) info dos address-pte __djgpp_base_address + (char *)&i'
`Page Table entry for address 0x11a00d30:'
`Base=0x02698000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0xd30'
This says that `i' is stored at offset `0xd30' from the page whose
physical base address is `0x02698000', and prints all the
attributes of that page.
Note that you must cast the addresses of variables to a `char *',
since otherwise the value of `__djgpp_base_address', the base
address of all variables and functions in a DJGPP program, will be
added using the rules of C pointer arithmetics: if `i' is declared
an `int', GDB will add 4 times the value of `__djgpp_base_address'
to the address of `i'.
Here's another example, it displays the Page Table entry for the
transfer buffer:
`(gdb) info dos address-pte *((unsigned *)&_go32_info_block + 3)'
`Page Table entry for address 0x29110:'
`Base=0x00029000 Dirty Acc. Not-Cached Write-Back Usr Read-Write +0x110'
(The `+ 3' offset is because the transfer buffer's address is the
3rd member of the `_go32_info_block' structure.) The output of
this command clearly shows that addresses in conventional memory
are mapped 1:1, i.e. the physical and linear addresses are
identical.
This command is supported only with some DPMI servers.
File: gdb.info, Node: Cygwin Native, Prev: DJGPP Native, Up: Native
Features for Debugging MS Windows PE executables
------------------------------------------------
GDB supports native debugging of MS Windows programs, including DLLs
with and without symbolic debugging information. There are various
additional Cygwin-specific commands, described in this subsection. The
subsubsection *note Non-debug DLL symbols:: describes working with DLLs
that have no debugging symbols.
`info w32'
This is a prefix of MS Windows specific commands which print
information about the target system and important OS structures.
`info w32 selector'
This command displays information returned by the Win32 API
`GetThreadSelectorEntry' function. It takes an optional argument
that is evaluated to a long value to give the information about
this given selector. Without argument, this command displays
information about the the six segment registers.
`info dll'
This is a Cygwin specific alias of info shared.
`dll-symbols'
This command loads symbols from a dll similarly to add-sym command
but without the need to specify a base address.
`set new-console MODE'
If MODE is `on' the debuggee will be started in a new console on
next start. If MODE is `off'i, the debuggee will be started in
the same console as the debugger.
`show new-console'
Displays whether a new console is used when the debuggee is
started.
`set new-group MODE'
This boolean value controls whether the debuggee should start a
new group or stay in the same group as the debugger. This affects
the way the Windows OS handles Ctrl-C.
`show new-group'
Displays current value of new-group boolean.
`set debugevents'
This boolean value adds debug output concerning events seen by the
debugger.
`set debugexec'
This boolean value adds debug output concerning execute events
seen by the debugger.
`set debugexceptions'
This boolean value adds debug ouptut concerning exception events
seen by the debugger.
`set debugmemory'
This boolean value adds debug ouptut concerning memory events seen
by the debugger.
`set shell'
This boolean values specifies whether the debuggee is called via a
shell or directly (default value is on).
`show shell'
Displays if the debuggee will be started with a shell.
* Menu:
* Non-debug DLL symbols:: Support for DLLs without debugging symbols
File: gdb.info, Node: Non-debug DLL symbols, Up: Cygwin Native
Support for DLLs without debugging symbols
..........................................
Very often on windows, some of the DLLs that your program relies on do
not include symbolic debugging information (for example,
`kernel32.dll'). When GDB doesn't recognize any debugging symbols in a
DLL, it relies on the minimal amount of symbolic information contained
in the DLL's export table. This subsubsection describes working with
such symbols, known internally to GDB as "minimal symbols".
Note that before the debugged program has started execution, no DLLs
will have been loaded. The easiest way around this problem is simply to
start the program -- either by setting a breakpoint or letting the
program run once to completion. It is also possible to force GDB to
load a particular DLL before starting the executable -- see the shared
library information in *note Files:: or the `dll-symbols' command in
*note Cygwin Native::. Currently, explicitly loading symbols from a DLL
with no debugging information will cause the symbol names to be
duplicated in GDB's lookup table, which may adversely affect symbol
lookup performance.
DLL name prefixes
.................
In keeping with the naming conventions used by the Microsoft debugging
tools, DLL export symbols are made available with a prefix based on the
DLL name, for instance `KERNEL32!CreateFileA'. The plain name is also
entered into the symbol table, so `CreateFileA' is often sufficient. In
some cases there will be name clashes within a program (particularly if
the executable itself includes full debugging symbols) necessitating
the use of the fully qualified name when referring to the contents of
the DLL. Use single-quotes around the name to avoid the exclamation
mark ("!") being interpreted as a language operator.
Note that the internal name of the DLL may be all upper-case, even
though the file name of the DLL is lower-case, or vice-versa. Since
symbols within GDB are _case-sensitive_ this may cause some confusion.
If in doubt, try the `info functions' and `info variables' commands or
even `maint print msymbols' (see *note Symbols::). Here's an example:
(gdb) info function CreateFileA
All functions matching regular expression "CreateFileA":
Non-debugging symbols:
0x77e885f4 CreateFileA
0x77e885f4 KERNEL32!CreateFileA
(gdb) info function !
All functions matching regular expression "!":
Non-debugging symbols:
0x6100114c cygwin1!__assert
0x61004034 cygwin1!_dll_crt0@0
0x61004240 cygwin1!dll_crt0(per_process *)
[etc...]
Working with minimal symbols
............................
Symbols extracted from a DLL's export table do not contain very much
type information. All that GDB can do is guess whether a symbol refers
to a function or variable depending on the linker section that contains
the symbol. Also note that the actual contents of the memory contained
in a DLL are not available unless the program is running. This means
that you cannot examine the contents of a variable or disassemble a
function within a DLL without a running program.
Variables are generally treated as pointers and dereferenced
automatically. For this reason, it is often necessary to prefix a
variable name with the address-of operator ("&") and provide explicit
type information in the command. Here's an example of the type of
problem:
(gdb) print 'cygwin1!__argv'
$1 = 268572168
(gdb) x 'cygwin1!__argv'
0x10021610: "\230y\""
And two possible solutions:
(gdb) print ((char **)'cygwin1!__argv')[0]
$2 = 0x22fd98 "/cygdrive/c/mydirectory/myprogram"
(gdb) x/2x &'cygwin1!__argv'
0x610c0aa8 <cygwin1!__argv>: 0x10021608 0x00000000
(gdb) x/x 0x10021608
0x10021608: 0x0022fd98
(gdb) x/s 0x0022fd98
0x22fd98: "/cygdrive/c/mydirectory/myprogram"
Setting a break point within a DLL is possible even before the
program starts execution. However, under these circumstances, GDB can't
examine the initial instructions of the function in order to skip the
function's frame set-up code. You can work around this by using "*&" to
set the breakpoint at a raw memory address:
(gdb) break *&'python22!PyOS_Readline'
Breakpoint 1 at 0x1e04eff0
The author of these extensions is not entirely convinced that
setting a break point within a shared DLL like `kernel32.dll' is
completely safe.
File: gdb.info, Node: Embedded OS, Next: Embedded Processors, Prev: Native, Up: Configurations
Embedded Operating Systems
==========================
This section describes configurations involving the debugging of
embedded operating systems that are available for several different
architectures.
* Menu:
* VxWorks:: Using GDB with VxWorks
GDB includes the ability to debug programs running on various
real-time operating systems.
File: gdb.info, Node: VxWorks, Up: Embedded OS
Using GDB with VxWorks
----------------------
`target vxworks MACHINENAME'
A VxWorks system, attached via TCP/IP. The argument MACHINENAME
is the target system's machine name or IP address.
On VxWorks, `load' links FILENAME dynamically on the current target
system as well as adding its symbols in GDB.
GDB enables developers to spawn and debug tasks running on networked
VxWorks targets from a Unix host. Already-running tasks spawned from
the VxWorks shell can also be debugged. GDB uses code that runs on
both the Unix host and on the VxWorks target. The program `gdb' is
installed and executed on the Unix host. (It may be installed with the
name `vxgdb', to distinguish it from a GDB for debugging programs on
the host itself.)
`VxWorks-timeout ARGS'
All VxWorks-based targets now support the option `vxworks-timeout'.
This option is set by the user, and ARGS represents the number of
seconds GDB waits for responses to rpc's. You might use this if
your VxWorks target is a slow software simulator or is on the far
side of a thin network line.
The following information on connecting to VxWorks was current when
this manual was produced; newer releases of VxWorks may use revised
procedures.
To use GDB with VxWorks, you must rebuild your VxWorks kernel to
include the remote debugging interface routines in the VxWorks library
`rdb.a'. To do this, define `INCLUDE_RDB' in the VxWorks configuration
file `configAll.h' and rebuild your VxWorks kernel. The resulting
kernel contains `rdb.a', and spawns the source debugging task
`tRdbTask' when VxWorks is booted. For more information on configuring
and remaking VxWorks, see the manufacturer's manual.
Once you have included `rdb.a' in your VxWorks system image and set
your Unix execution search path to find GDB, you are ready to run GDB.
From your Unix host, run `gdb' (or `vxgdb', depending on your
installation).
GDB comes up showing the prompt:
(vxgdb)
* Menu:
* VxWorks Connection:: Connecting to VxWorks
* VxWorks Download:: VxWorks download
* VxWorks Attach:: Running tasks
File: gdb.info, Node: VxWorks Connection, Next: VxWorks Download, Up: VxWorks
Connecting to VxWorks
.....................
The GDB command `target' lets you connect to a VxWorks target on the
network. To connect to a target whose host name is "`tt'", type:
(vxgdb) target vxworks tt
GDB displays messages like these:
Attaching remote machine across net...
Connected to tt.
GDB then attempts to read the symbol tables of any object modules
loaded into the VxWorks target since it was last booted. GDB locates
these files by searching the directories listed in the command search
path (*note Your program's environment: Environment.); if it fails to
find an object file, it displays a message such as:
prog.o: No such file or directory.
When this happens, add the appropriate directory to the search path
with the GDB command `path', and execute the `target' command again.
File: gdb.info, Node: VxWorks Download, Next: VxWorks Attach, Prev: VxWorks Connection, Up: VxWorks
VxWorks download
................
If you have connected to the VxWorks target and you want to debug an
object that has not yet been loaded, you can use the GDB `load' command
to download a file from Unix to VxWorks incrementally. The object file
given as an argument to the `load' command is actually opened twice:
first by the VxWorks target in order to download the code, then by GDB
in order to read the symbol table. This can lead to problems if the
current working directories on the two systems differ. If both systems
have NFS mounted the same filesystems, you can avoid these problems by
using absolute paths. Otherwise, it is simplest to set the working
directory on both systems to the directory in which the object file
resides, and then to reference the file by its name, without any path.
For instance, a program `prog.o' may reside in `VXPATH/vw/demo/rdb' in
VxWorks and in `HOSTPATH/vw/demo/rdb' on the host. To load this
program, type this on VxWorks:
-> cd "VXPATH/vw/demo/rdb"
Then, in GDB, type:
(vxgdb) cd HOSTPATH/vw/demo/rdb
(vxgdb) load prog.o
GDB displays a response similar to this:
Reading symbol data from wherever/vw/demo/rdb/prog.o... done.
You can also use the `load' command to reload an object module after
editing and recompiling the corresponding source file. Note that this
makes GDB delete all currently-defined breakpoints, auto-displays, and
convenience variables, and to clear the value history. (This is
necessary in order to preserve the integrity of debugger's data
structures that reference the target system's symbol table.)
File: gdb.info, Node: VxWorks Attach, Prev: VxWorks Download, Up: VxWorks
Running tasks
.............
You can also attach to an existing task using the `attach' command as
follows:
(vxgdb) attach TASK
where TASK is the VxWorks hexadecimal task ID. The task can be running
or suspended when you attach to it. Running tasks are suspended at the
time of attachment.
File: gdb.info, Node: Embedded Processors, Next: Architectures, Prev: Embedded OS, Up: Configurations
Embedded Processors
===================
This section goes into details specific to particular embedded
configurations.
* Menu:
* ARM:: ARM
* H8/300:: Renesas H8/300
* H8/500:: Renesas H8/500
* M32R/D:: Renesas M32R/D
* M68K:: Motorola M68K
* MIPS Embedded:: MIPS Embedded
* OpenRISC 1000:: OpenRisc 1000
* PA:: HP PA Embedded
* PowerPC: PowerPC
* SH:: Renesas SH
* Sparclet:: Tsqware Sparclet
* Sparclite:: Fujitsu Sparclite
* ST2000:: Tandem ST2000
* Z8000:: Zilog Z8000
File: gdb.info, Node: ARM, Next: H8/300, Up: Embedded Processors
ARM
---
`target rdi DEV'
ARM Angel monitor, via RDI library interface to ADP protocol. You
may use this target to communicate with both boards running the
Angel monitor, or with the EmbeddedICE JTAG debug device.
`target rdp DEV'
ARM Demon monitor.
File: gdb.info, Node: H8/300, Next: H8/500, Prev: ARM, Up: Embedded Processors
Renesas H8/300
--------------
`target hms DEV'
A Renesas SH, H8/300, or H8/500 board, attached via serial line to
your host. Use special commands `device' and `speed' to control
the serial line and the communications speed used.
`target e7000 DEV'
E7000 emulator for Renesas H8 and SH.
`target sh3 DEV'
`target sh3e DEV'
Renesas SH-3 and SH-3E target systems.
When you select remote debugging to a Renesas SH, H8/300, or H8/500
board, the `load' command downloads your program to the Renesas board
and also opens it as the current executable target for GDB on your host
(like the `file' command).
GDB needs to know these things to talk to your Renesas SH, H8/300,
or H8/500:
1. that you want to use `target hms', the remote debugging interface
for Renesas microprocessors, or `target e7000', the in-circuit
emulator for the Renesas SH and the Renesas 300H. (`target hms' is
the default when GDB is configured specifically for the Renesas SH,
H8/300, or H8/500.)
2. what serial device connects your host to your Renesas board (the
first serial device available on your host is the default).
3. what speed to use over the serial device.
* Menu:
* Renesas Boards:: Connecting to Renesas boards.
* Renesas ICE:: Using the E7000 In-Circuit Emulator.
* Renesas Special:: Special GDB commands for Renesas micros.
File: gdb.info, Node: Renesas Boards, Next: Renesas ICE, Up: H8/300
Connecting to Renesas boards
............................
Use the special `GDB' command `device PORT' if you need to explicitly
set the serial device. The default PORT is the first available port on
your host. This is only necessary on Unix hosts, where it is typically
something like `/dev/ttya'.
`GDB' has another special command to set the communications speed:
`speed BPS'. This command also is only used from Unix hosts; on DOS
hosts, set the line speed as usual from outside GDB with the DOS `mode'
command (for instance, `mode com2:9600,n,8,1,p' for a 9600bps
connection).
The `device' and `speed' commands are available only when you use a
Unix host to debug your Renesas microprocessor programs. If you use a
DOS host, GDB depends on an auxiliary terminate-and-stay-resident
program called `asynctsr' to communicate with the development board
through a PC serial port. You must also use the DOS `mode' command to
set up the serial port on the DOS side.
The following sample session illustrates the steps needed to start a
program under GDB control on an H8/300. The example uses a sample
H8/300 program called `t.x'. The procedure is the same for the Renesas
SH and the H8/500.
First hook up your development board. In this example, we use a
board attached to serial port `COM2'; if you use a different serial
port, substitute its name in the argument of the `mode' command. When
you call `asynctsr', the auxiliary comms program used by the debugger,
you give it just the numeric part of the serial port's name; for
example, `asyncstr 2' below runs `asyncstr' on `COM2'.
C:\H8300\TEST> asynctsr 2
C:\H8300\TEST> mode com2:9600,n,8,1,p
Resident portion of MODE loaded
COM2: 9600, n, 8, 1, p
_Warning:_ We have noticed a bug in PC-NFS that conflicts with
`asynctsr'. If you also run PC-NFS on your DOS host, you may need
to disable it, or even boot without it, to use `asynctsr' to
control your development board.
Now that serial communications are set up, and the development board
is connected, you can start up GDB. Call `gdb' with the name of your
program as the argument. `GDB' prompts you, as usual, with the prompt
`(gdb)'. Use two special commands to begin your debugging session:
`target hms' to specify cross-debugging to the Renesas board, and the
`load' command to download your program to the board. `load' displays
the names of the program's sections, and a `*' for each 2K of data
downloaded. (If you want to refresh GDB data on symbols or on the
executable file without downloading, use the GDB commands `file' or
`symbol-file'. These commands, and `load' itself, are described in
*Note Commands to specify files: Files.)
(eg-C:\H8300\TEST) gdb t.x
GDB is free software and you are welcome to distribute copies
of it under certain conditions; type "show copying" to see
the conditions.
There is absolutely no warranty for GDB; type "show warranty"
for details.
GDB 6.1.1, Copyright 1992 Free Software Foundation, Inc...
(gdb) target hms
Connected to remote H8/300 HMS system.
(gdb) load t.x
.text : 0x8000 .. 0xabde ***********
.data : 0xabde .. 0xad30 *
.stack : 0xf000 .. 0xf014 *
At this point, you're ready to run or debug your program. From here
on, you can use all the usual GDB commands. The `break' command sets
breakpoints; the `run' command starts your program; `print' or `x'
display data; the `continue' command resumes execution after stopping
at a breakpoint. You can use the `help' command at any time to find
out more about GDB commands.
Remember, however, that _operating system_ facilities aren't
available on your development board; for example, if your program hangs,
you can't send an interrupt--but you can press the RESET switch!
Use the RESET button on the development board
* to interrupt your program (don't use `ctl-C' on the DOS host--it
has no way to pass an interrupt signal to the development board);
and
* to return to the GDB command prompt after your program finishes
normally. The communications protocol provides no other way for
GDB to detect program completion.
In either case, GDB sees the effect of a RESET on the development
board as a "normal exit" of your program.
File: gdb.info, Node: Renesas ICE, Next: Renesas Special, Prev: Renesas Boards, Up: H8/300
Using the E7000 in-circuit emulator
...................................
You can use the E7000 in-circuit emulator to develop code for either the
Renesas SH or the H8/300H. Use one of these forms of the `target
e7000' command to connect GDB to your E7000:
`target e7000 PORT SPEED'
Use this form if your E7000 is connected to a serial port. The
PORT argument identifies what serial port to use (for example,
`com2'). The third argument is the line speed in bits per second
(for example, `9600').
`target e7000 HOSTNAME'
If your E7000 is installed as a host on a TCP/IP network, you can
just specify its hostname; GDB uses `telnet' to connect.
File: gdb.info, Node: Renesas Special, Prev: Renesas ICE, Up: H8/300
Special GDB commands for Renesas micros
.......................................
Some GDB commands are available only for the H8/300:
`set machine h8300'
`set machine h8300h'
Condition GDB for one of the two variants of the H8/300
architecture with `set machine'. You can use `show machine' to
check which variant is currently in effect.
File: gdb.info, Node: H8/500, Next: M32R/D, Prev: H8/300, Up: Embedded Processors
H8/500
------
`set memory MOD'
`show memory'
Specify which H8/500 memory model (MOD) you are using with `set
memory'; check which memory model is in effect with `show memory'.
The accepted values for MOD are `small', `big', `medium', and
`compact'.
File: gdb.info, Node: M32R/D, Next: M68K, Prev: H8/500, Up: Embedded Processors
Renesas M32R/D
--------------
`target m32r DEV'
Renesas M32R/D ROM monitor.
`target m32rsdi DEV'
Renesas M32R SDI server, connected via parallel port to the board.
File: gdb.info, Node: M68K, Next: MIPS Embedded, Prev: M32R/D, Up: Embedded Processors
M68k
----
The Motorola m68k configuration includes ColdFire support, and target
command for the following ROM monitors.
`target abug DEV'
ABug ROM monitor for M68K.
`target cpu32bug DEV'
CPU32BUG monitor, running on a CPU32 (M68K) board.
`target dbug DEV'
dBUG ROM monitor for Motorola ColdFire.
`target est DEV'
EST-300 ICE monitor, running on a CPU32 (M68K) board.
`target rom68k DEV'
ROM 68K monitor, running on an M68K IDP board.
`target rombug DEV'
ROMBUG ROM monitor for OS/9000.
File: gdb.info, Node: MIPS Embedded, Next: OpenRISC 1000, Prev: M68K, Up: Embedded Processors
MIPS Embedded
-------------
GDB can use the MIPS remote debugging protocol to talk to a MIPS board
attached to a serial line. This is available when you configure GDB
with `--target=mips-idt-ecoff'.
Use these GDB commands to specify the connection to your target
board:
`target mips PORT'
To run a program on the board, start up `gdb' with the name of
your program as the argument. To connect to the board, use the
command `target mips PORT', where PORT is the name of the serial
port connected to the board. If the program has not already been
downloaded to the board, you may use the `load' command to
download it. You can then use all the usual GDB commands.
For example, this sequence connects to the target board through a
serial port, and loads and runs a program called PROG through the
debugger:
host$ gdb PROG
GDB is free software and ...
(gdb) target mips /dev/ttyb
(gdb) load PROG
(gdb) run
`target mips HOSTNAME:PORTNUMBER'
On some GDB host configurations, you can specify a TCP connection
(for instance, to a serial line managed by a terminal
concentrator) instead of a serial port, using the syntax
`HOSTNAME:PORTNUMBER'.
`target pmon PORT'
PMON ROM monitor.
`target ddb PORT'
NEC's DDB variant of PMON for Vr4300.
`target lsi PORT'
LSI variant of PMON.
`target r3900 DEV'
Densan DVE-R3900 ROM monitor for Toshiba R3900 Mips.
`target array DEV'
Array Tech LSI33K RAID controller board.
GDB also supports these special commands for MIPS targets:
`set processor ARGS'
`show processor'
Use the `set processor' command to set the type of MIPS processor
when you want to access processor-type-specific registers. For
example, `set processor R3041' tells GDB to use the CPU registers
appropriate for the 3041 chip. Use the `show processor' command
to see what MIPS processor GDB is using. Use the `info reg'
command to see what registers GDB is using.
`set mipsfpu double'
`set mipsfpu single'
`set mipsfpu none'
`show mipsfpu'
If your target board does not support the MIPS floating point
coprocessor, you should use the command `set mipsfpu none' (if you
need this, you may wish to put the command in your GDB init file).
This tells GDB how to find the return value of functions which
return floating point values. It also allows GDB to avoid saving
the floating point registers when calling functions on the board.
If you are using a floating point coprocessor with only single
precision floating point support, as on the R4650 processor, use
the command `set mipsfpu single'. The default double precision
floating point coprocessor may be selected using `set mipsfpu
double'.
In previous versions the only choices were double precision or no
floating point, so `set mipsfpu on' will select double precision
and `set mipsfpu off' will select no floating point.
As usual, you can inquire about the `mipsfpu' variable with `show
mipsfpu'.
`set remotedebug N'
`show remotedebug'
You can see some debugging information about communications with
the board by setting the `remotedebug' variable. If you set it to
`1' using `set remotedebug 1', every packet is displayed. If you
set it to `2', every character is displayed. You can check the
current value at any time with the command `show remotedebug'.
`set timeout SECONDS'
`set retransmit-timeout SECONDS'
`show timeout'
`show retransmit-timeout'
You can control the timeout used while waiting for a packet, in
the MIPS remote protocol, with the `set timeout SECONDS' command.
The default is 5 seconds. Similarly, you can control the timeout
used while waiting for an acknowledgement of a packet with the `set
retransmit-timeout SECONDS' command. The default is 3 seconds.
You can inspect both values with `show timeout' and `show
retransmit-timeout'. (These commands are _only_ available when
GDB is configured for `--target=mips-idt-ecoff'.)
The timeout set by `set timeout' does not apply when GDB is
waiting for your program to stop. In that case, GDB waits forever
because it has no way of knowing how long the program is going to
run before stopping.
File: gdb.info, Node: OpenRISC 1000, Next: PA, Prev: MIPS Embedded, Up: Embedded Processors
OpenRISC 1000
-------------
See OR1k Architecture document (`www.opencores.org') for more
information about platform and commands.
`target jtag jtag://HOST:PORT'
Connects to remote JTAG server. JTAG remote server can be either
an or1ksim or JTAG server, connected via parallel port to the
board.
Example: `target jtag jtag://localhost:9999'
`or1ksim COMMAND'
If connected to `or1ksim' OpenRISC 1000 Architectural Simulator,
proprietary commands can be executed.
`info or1k spr'
Displays spr groups.
`info or1k spr GROUP'
`info or1k spr GROUPNO'
Displays register names in selected group.
`info or1k spr GROUP REGISTER'
`info or1k spr REGISTER'
`info or1k spr GROUPNO REGISTERNO'
`info or1k spr REGISTERNO'
Shows information about specified spr register.
`spr GROUP REGISTER VALUE'
`spr REGISTER VALUE'
`spr GROUPNO REGISTERNO VALUE'
`spr REGISTERNO VALUE'
Writes VALUE to specified spr register.
Some implementations of OpenRISC 1000 Architecture also have
hardware trace. It is very similar to GDB trace, except it does not
interfere with normal program execution and is thus much faster.
Hardware breakpoints/watchpoint triggers can be set using:
`$LEA/$LDATA'
Load effective address/data
`$SEA/$SDATA'
Store effective address/data
`$AEA/$ADATA'
Access effective address ($SEA or $LEA) or data ($SDATA/$LDATA)
`$FETCH'
Fetch data
When triggered, it can capture low level data, like: `PC', `LSEA',
`LDATA', `SDATA', `READSPR', `WRITESPR', `INSTR'.
`htrace' commands:
`hwatch CONDITIONAL'
Set hardware watchpoint on combination of Load/Store Effecive
Address(es) or Data. For example:
`hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) &&
($SDATA >= 50)'
`hwatch ($LEA == my_var) && ($LDATA < 50) || ($SEA == my_var) &&
($SDATA >= 50)'
`htrace info'
Display information about current HW trace configuration.
`htrace trigger CONDITIONAL'
Set starting criteria for HW trace.
`htrace qualifier CONDITIONAL'
Set acquisition qualifier for HW trace.
`htrace stop CONDITIONAL'
Set HW trace stopping criteria.
`htrace record [DATA]*'
Selects the data to be recorded, when qualifier is met and HW
trace was triggered.
`htrace enable'
`htrace disable'
Enables/disables the HW trace.
`htrace rewind [FILENAME]'
Clears currently recorded trace data.
If filename is specified, new trace file is made and any newly
collected data will be written there.
`htrace print [START [LEN]]'
Prints trace buffer, using current record configuration.
`htrace mode continuous'
Set continuous trace mode.
`htrace mode suspend'
Set suspend trace mode.
File: gdb.info, Node: PowerPC, Next: SH, Prev: PA, Up: Embedded Processors
PowerPC
-------
`target dink32 DEV'
DINK32 ROM monitor.
`target ppcbug DEV'
`target ppcbug1 DEV'
PPCBUG ROM monitor for PowerPC.
`target sds DEV'
SDS monitor, running on a PowerPC board (such as Motorola's ADS).
File: gdb.info, Node: PA, Next: PowerPC, Prev: OpenRISC 1000, Up: Embedded Processors
HP PA Embedded
--------------
`target op50n DEV'
OP50N monitor, running on an OKI HPPA board.
`target w89k DEV'
W89K monitor, running on a Winbond HPPA board.
File: gdb.info, Node: SH, Next: Sparclet, Prev: PowerPC, Up: Embedded Processors
Renesas SH
----------
`target hms DEV'
A Renesas SH board attached via serial line to your host. Use
special commands `device' and `speed' to control the serial line
and the communications speed used.
`target e7000 DEV'
E7000 emulator for Renesas SH.
`target sh3 DEV'
`target sh3e DEV'
Renesas SH-3 and SH-3E target systems.
File: gdb.info, Node: Sparclet, Next: Sparclite, Prev: SH, Up: Embedded Processors
Tsqware Sparclet
----------------
GDB enables developers to debug tasks running on Sparclet targets from
a Unix host. GDB uses code that runs on both the Unix host and on the
Sparclet target. The program `gdb' is installed and executed on the
Unix host.
`remotetimeout ARGS'
GDB supports the option `remotetimeout'. This option is set by
the user, and ARGS represents the number of seconds GDB waits for
responses.
When compiling for debugging, include the options `-g' to get debug
information and `-Ttext' to relocate the program to where you wish to
load it on the target. You may also want to add the options `-n' or
`-N' in order to reduce the size of the sections. Example:
sparclet-aout-gcc prog.c -Ttext 0x12010000 -g -o prog -N
You can use `objdump' to verify that the addresses are what you
intended:
sparclet-aout-objdump --headers --syms prog
Once you have set your Unix execution search path to find GDB, you
are ready to run GDB. From your Unix host, run `gdb' (or
`sparclet-aout-gdb', depending on your installation).
GDB comes up showing the prompt:
(gdbslet)
* Menu:
* Sparclet File:: Setting the file to debug
* Sparclet Connection:: Connecting to Sparclet
* Sparclet Download:: Sparclet download
* Sparclet Execution:: Running and debugging
File: gdb.info, Node: Sparclet File, Next: Sparclet Connection, Up: Sparclet
Setting file to debug
.....................
The GDB command `file' lets you choose with program to debug.
(gdbslet) file prog
GDB then attempts to read the symbol table of `prog'. GDB locates
the file by searching the directories listed in the command search path.
If the file was compiled with debug information (option "-g"), source
files will be searched as well. GDB locates the source files by
searching the directories listed in the directory search path (*note
Your program's environment: Environment.). If it fails to find a file,
it displays a message such as:
prog: No such file or directory.
When this happens, add the appropriate directories to the search
paths with the GDB commands `path' and `dir', and execute the `target'
command again.
File: gdb.info, Node: Sparclet Connection, Next: Sparclet Download, Prev: Sparclet File, Up: Sparclet
Connecting to Sparclet
......................
The GDB command `target' lets you connect to a Sparclet target. To
connect to a target on serial port "`ttya'", type:
(gdbslet) target sparclet /dev/ttya
Remote target sparclet connected to /dev/ttya
main () at ../prog.c:3
GDB displays messages like these:
Connected to ttya.
File: gdb.info, Node: Sparclet Download, Next: Sparclet Execution, Prev: Sparclet Connection, Up: Sparclet
Sparclet download
.................
Once connected to the Sparclet target, you can use the GDB `load'
command to download the file from the host to the target. The file
name and load offset should be given as arguments to the `load' command.
Since the file format is aout, the program must be loaded to the
starting address. You can use `objdump' to find out what this value
is. The load offset is an offset which is added to the VMA (virtual
memory address) of each of the file's sections. For instance, if the
program `prog' was linked to text address 0x1201000, with data at
0x12010160 and bss at 0x12010170, in GDB, type:
(gdbslet) load prog 0x12010000
Loading section .text, size 0xdb0 vma 0x12010000
If the code is loaded at a different address then what the program
was linked to, you may need to use the `section' and `add-symbol-file'
commands to tell GDB where to map the symbol table.
File: gdb.info, Node: Sparclet Execution, Prev: Sparclet Download, Up: Sparclet
Running and debugging
.....................
You can now begin debugging the task using GDB's execution control
commands, `b', `step', `run', etc. See the GDB manual for the list of
commands.
(gdbslet) b main
Breakpoint 1 at 0x12010000: file prog.c, line 3.
(gdbslet) run
Starting program: prog
Breakpoint 1, main (argc=1, argv=0xeffff21c) at prog.c:3
3 char *symarg = 0;
(gdbslet) step
4 char *execarg = "hello!";
(gdbslet)
File: gdb.info, Node: Sparclite, Next: ST2000, Prev: Sparclet, Up: Embedded Processors
Fujitsu Sparclite
-----------------
`target sparclite DEV'
Fujitsu sparclite boards, used only for the purpose of loading.
You must use an additional command to debug the program. For
example: target remote DEV using GDB standard remote protocol.
File: gdb.info, Node: ST2000, Next: Z8000, Prev: Sparclite, Up: Embedded Processors
Tandem ST2000
-------------
GDB may be used with a Tandem ST2000 phone switch, running Tandem's
STDBUG protocol.
To connect your ST2000 to the host system, see the manufacturer's
manual. Once the ST2000 is physically attached, you can run:
target st2000 DEV SPEED
to establish it as your debugging environment. DEV is normally the
name of a serial device, such as `/dev/ttya', connected to the ST2000
via a serial line. You can instead specify DEV as a TCP connection
(for example, to a serial line attached via a terminal concentrator)
using the syntax `HOSTNAME:PORTNUMBER'.
The `load' and `attach' commands are _not_ defined for this target;
you must load your program into the ST2000 as you normally would for
standalone operation. GDB reads debugging information (such as
symbols) from a separate, debugging version of the program available on
your host computer.
These auxiliary GDB commands are available to help you with the
ST2000 environment:
`st2000 COMMAND'
Send a COMMAND to the STDBUG monitor. See the manufacturer's
manual for available commands.
`connect'
Connect the controlling terminal to the STDBUG command monitor.
When you are done interacting with STDBUG, typing either of two
character sequences gets you back to the GDB command prompt:
`<RET>~.' (Return, followed by tilde and period) or `<RET>~<C-d>'
(Return, followed by tilde and control-D).
File: gdb.info, Node: Z8000, Prev: ST2000, Up: Embedded Processors
Zilog Z8000
-----------
When configured for debugging Zilog Z8000 targets, GDB includes a Z8000
simulator.
For the Z8000 family, `target sim' simulates either the Z8002 (the
unsegmented variant of the Z8000 architecture) or the Z8001 (the
segmented variant). The simulator recognizes which architecture is
appropriate by inspecting the object code.
`target sim ARGS'
Debug programs on a simulated CPU. If the simulator supports setup
options, specify them via ARGS.
After specifying this target, you can debug programs for the simulated
CPU in the same style as programs for your host computer; use the
`file' command to load a new program image, the `run' command to run
your program, and so on.
As well as making available all the usual machine registers (*note
Registers: Registers.), the Z8000 simulator provides three additional
items of information as specially named registers:
`cycles'
Counts clock-ticks in the simulator.
`insts'
Counts instructions run in the simulator.
`time'
Execution time in 60ths of a second.
You can refer to these values in GDB expressions with the usual
conventions; for example, `b fputc if $cycles>5000' sets a conditional
breakpoint that suspends only after at least 5000 simulated clock ticks.
File: gdb.info, Node: Architectures, Prev: Embedded Processors, Up: Configurations
Architectures
=============
This section describes characteristics of architectures that affect all
uses of GDB with the architecture, both native and cross.
* Menu:
* A29K::
* Alpha::
* MIPS::
File: gdb.info, Node: A29K, Next: Alpha, Up: Architectures
A29K
----
`set rstack_high_address ADDRESS'
On AMD 29000 family processors, registers are saved in a separate
"register stack". There is no way for GDB to determine the extent
of this stack. Normally, GDB just assumes that the stack is
"large enough". This may result in GDB referencing memory
locations that do not exist. If necessary, you can get around
this problem by specifying the ending address of the register
stack with the `set rstack_high_address' command. The argument
should be an address, which you probably want to precede with `0x'
to specify in hexadecimal.
`show rstack_high_address'
Display the current limit of the register stack, on AMD 29000
family processors.
File: gdb.info, Node: Alpha, Next: MIPS, Prev: A29K, Up: Architectures
Alpha
-----
See the following section.
File: gdb.info, Node: MIPS, Prev: Alpha, Up: Architectures
MIPS
----
Alpha- and MIPS-based computers use an unusual stack frame, which
sometimes requires GDB to search backward in the object code to find
the beginning of a function.
To improve response time (especially for embedded applications, where
GDB may be restricted to a slow serial line for this search) you may
want to limit the size of this search, using one of these commands:
`set heuristic-fence-post LIMIT'
Restrict GDB to examining at most LIMIT bytes in its search for
the beginning of a function. A value of 0 (the default) means
there is no limit. However, except for 0, the larger the limit
the more bytes `heuristic-fence-post' must search and therefore
the longer it takes to run.
`show heuristic-fence-post'
Display the current limit.
These commands are available _only_ when GDB is configured for
debugging programs on Alpha or MIPS processors.
File: gdb.info, Node: Controlling GDB, Next: Sequences, Prev: Configurations, Up: Top
Controlling GDB
***************
You can alter the way GDB interacts with you by using the `set'
command. For commands controlling how GDB displays data, see *Note
Print settings: Print Settings. Other settings are described here.
* Menu:
* Prompt:: Prompt
* Editing:: Command editing
* History:: Command history
* Screen Size:: Screen size
* Numbers:: Numbers
* ABI:: Configuring the current ABI
* Messages/Warnings:: Optional warnings and messages
* Debugging Output:: Optional messages about internal happenings
File: gdb.info, Node: Prompt, Next: Editing, Up: Controlling GDB
Prompt
======
GDB indicates its readiness to read a command by printing a string
called the "prompt". This string is normally `(gdb)'. You can change
the prompt string with the `set prompt' command. For instance, when
debugging GDB with GDB, it is useful to change the prompt in one of the
GDB sessions so that you can always tell which one you are talking to.
_Note:_ `set prompt' does not add a space for you after the prompt
you set. This allows you to set a prompt which ends in a space or a
prompt that does not.
`set prompt NEWPROMPT'
Directs GDB to use NEWPROMPT as its prompt string henceforth.
`show prompt'
Prints a line of the form: `Gdb's prompt is: YOUR-PROMPT'
File: gdb.info, Node: Editing, Next: History, Prev: Prompt, Up: Controlling GDB
Command editing
===============
GDB reads its input commands via the "readline" interface. This GNU
library provides consistent behavior for programs which provide a
command line interface to the user. Advantages are GNU Emacs-style or
"vi"-style inline editing of commands, `csh'-like history substitution,
and a storage and recall of command history across debugging sessions.
You may control the behavior of command line editing in GDB with the
command `set'.
`set editing'
`set editing on'
Enable command line editing (enabled by default).
`set editing off'
Disable command line editing.
`show editing'
Show whether command line editing is enabled.
File: gdb.info, Node: History, Next: Screen Size, Prev: Editing, Up: Controlling GDB
Command history
===============
GDB can keep track of the commands you type during your debugging
sessions, so that you can be certain of precisely what happened. Use
these commands to manage the GDB command history facility.
`set history filename FNAME'
Set the name of the GDB command history file to FNAME. This is
the file where GDB reads an initial command history list, and
where it writes the command history from this session when it
exits. You can access this list through history expansion or
through the history command editing characters listed below. This
file defaults to the value of the environment variable
`GDBHISTFILE', or to `./.gdb_history' (`./_gdb_history' on MS-DOS)
if this variable is not set.
`set history save'
`set history save on'
Record command history in a file, whose name may be specified with
the `set history filename' command. By default, this option is
disabled.
`set history save off'
Stop recording command history in a file.
`set history size SIZE'
Set the number of commands which GDB keeps in its history list.
This defaults to the value of the environment variable `HISTSIZE',
or to 256 if this variable is not set.
History expansion assigns special meaning to the character `!'.
Since `!' is also the logical not operator in C, history expansion
is off by default. If you decide to enable history expansion with the
`set history expansion on' command, you may sometimes need to follow
`!' (when it is used as logical not, in an expression) with a space or
a tab to prevent it from being expanded. The readline history
facilities do not attempt substitution on the strings `!=' and `!(',
even when history expansion is enabled.
The commands to control history expansion are:
`set history expansion on'
`set history expansion'
Enable history expansion. History expansion is off by default.
`set history expansion off'
Disable history expansion.
The readline code comes with more complete documentation of
editing and history expansion features. Users unfamiliar with GNU
Emacs or `vi' may wish to read it.
`show history'
`show history filename'
`show history save'
`show history size'
`show history expansion'
These commands display the state of the GDB history parameters.
`show history' by itself displays all four states.
`show commands'
Display the last ten commands in the command history.
`show commands N'
Print ten commands centered on command number N.
`show commands +'
Print ten commands just after the commands last printed.
File: gdb.info, Node: Screen Size, Next: Numbers, Prev: History, Up: Controlling GDB
Screen size
===========
Certain commands to GDB may produce large amounts of information output
to the screen. To help you read all of it, GDB pauses and asks you for
input at the end of each page of output. Type <RET> when you want to
continue the output, or `q' to discard the remaining output. Also, the
screen width setting determines when to wrap lines of output.
Depending on what is being printed, GDB tries to break the line at a
readable place, rather than simply letting it overflow onto the
following line.
Normally GDB knows the size of the screen from the terminal driver
software. For example, on Unix GDB uses the termcap data base together
with the value of the `TERM' environment variable and the `stty rows'
and `stty cols' settings. If this is not correct, you can override it
with the `set height' and `set width' commands:
`set height LPP'
`show height'
`set width CPL'
`show width'
These `set' commands specify a screen height of LPP lines and a
screen width of CPL characters. The associated `show' commands
display the current settings.
If you specify a height of zero lines, GDB does not pause during
output no matter how long the output is. This is useful if output
is to a file or to an editor buffer.
Likewise, you can specify `set width 0' to prevent GDB from
wrapping its output.
File: gdb.info, Node: Numbers, Next: ABI, Prev: Screen Size, Up: Controlling GDB
Numbers
=======
You can always enter numbers in octal, decimal, or hexadecimal in GDB
by the usual conventions: octal numbers begin with `0', decimal numbers
end with `.', and hexadecimal numbers begin with `0x'. Numbers that
begin with none of these are, by default, entered in base 10; likewise,
the default display for numbers--when no particular format is
specified--is base 10. You can change the default base for both input
and output with the `set radix' command.
`set input-radix BASE'
Set the default base for numeric input. Supported choices for
BASE are decimal 8, 10, or 16. BASE must itself be specified
either unambiguously or using the current default radix; for
example, any of
set radix 012
set radix 10.
set radix 0xa
sets the base to decimal. On the other hand, `set radix 10'
leaves the radix unchanged no matter what it was.
`set output-radix BASE'
Set the default base for numeric display. Supported choices for
BASE are decimal 8, 10, or 16. BASE must itself be specified
either unambiguously or using the current default radix.
`show input-radix'
Display the current default base for numeric input.
`show output-radix'
Display the current default base for numeric display.
File: gdb.info, Node: ABI, Next: Messages/Warnings, Prev: Numbers, Up: Controlling GDB
Configuring the current ABI
===========================
GDB can determine the "ABI" (Application Binary Interface) of your
application automatically. However, sometimes you need to override its
conclusions. Use these commands to manage GDB's view of the current
ABI.
One GDB configuration can debug binaries for multiple operating
system targets, either via remote debugging or native emulation. GDB
will autodetect the "OS ABI" (Operating System ABI) in use, but you can
override its conclusion using the `set osabi' command. One example
where this is useful is in debugging of binaries which use an alternate
C library (e.g. UCLIBC for GNU/Linux) which does not have the same
identifying marks that the standard C library for your platform
provides.
`show osabi'
Show the OS ABI currently in use.
`set osabi'
With no argument, show the list of registered available OS ABI's.
`set osabi ABI'
Set the current OS ABI to ABI.
Generally, the way that an argument of type `float' is passed to a
function depends on whether the function is prototyped. For a
prototyped (i.e. ANSI/ISO style) function, `float' arguments are passed
unchanged, according to the architecture's convention for `float'. For
unprototyped (i.e. K&R style) functions, `float' arguments are first
promoted to type `double' and then passed.
Unfortunately, some forms of debug information do not reliably
indicate whether a function is prototyped. If GDB calls a function
that is not marked as prototyped, it consults `set
coerce-float-to-double'.
`set coerce-float-to-double'
`set coerce-float-to-double on'
Arguments of type `float' will be promoted to `double' when passed
to an unprototyped function. This is the default setting.
`set coerce-float-to-double off'
Arguments of type `float' will be passed directly to unprototyped
functions.
GDB needs to know the ABI used for your program's C++ objects. The
correct C++ ABI depends on which C++ compiler was used to build your
application. GDB only fully supports programs with a single C++ ABI;
if your program contains code using multiple C++ ABI's or if GDB can
not identify your program's ABI correctly, you can tell GDB which ABI
to use. Currently supported ABI's include "gnu-v2", for `g++' versions
before 3.0, "gnu-v3", for `g++' versions 3.0 and later, and "hpaCC" for
the HP ANSI C++ compiler. Other C++ compilers may use the "gnu-v2" or
"gnu-v3" ABI's as well. The default setting is "auto".
`show cp-abi'
Show the C++ ABI currently in use.
`set cp-abi'
With no argument, show the list of supported C++ ABI's.
`set cp-abi ABI'
`set cp-abi auto'
Set the current C++ ABI to ABI, or return to automatic detection.
File: gdb.info, Node: Messages/Warnings, Next: Debugging Output, Prev: ABI, Up: Controlling GDB
Optional warnings and messages
==============================
By default, GDB is silent about its inner workings. If you are running
on a slow machine, you may want to use the `set verbose' command. This
makes GDB tell you when it does a lengthy internal operation, so you
will not think it has crashed.
Currently, the messages controlled by `set verbose' are those which
announce that the symbol table for a source file is being read; see
`symbol-file' in *Note Commands to specify files: Files.
`set verbose on'
Enables GDB output of certain informational messages.
`set verbose off'
Disables GDB output of certain informational messages.
`show verbose'
Displays whether `set verbose' is on or off.
By default, if GDB encounters bugs in the symbol table of an object
file, it is silent; but if you are debugging a compiler, you may find
this information useful (*note Errors reading symbol files: Symbol
Errors.).
`set complaints LIMIT'
Permits GDB to output LIMIT complaints about each type of unusual
symbols before becoming silent about the problem. Set LIMIT to
zero to suppress all complaints; set it to a large number to
prevent complaints from being suppressed.
`show complaints'
Displays how many symbol complaints GDB is permitted to produce.
By default, GDB is cautious, and asks what sometimes seems to be a
lot of stupid questions to confirm certain commands. For example, if
you try to run a program which is already running:
(gdb) run
The program being debugged has been started already.
Start it from the beginning? (y or n)
If you are willing to unflinchingly face the consequences of your own
commands, you can disable this "feature":
`set confirm off'
Disables confirmation requests.
`set confirm on'
Enables confirmation requests (the default).
`show confirm'
Displays state of confirmation requests.
File: gdb.info, Node: Debugging Output, Prev: Messages/Warnings, Up: Controlling GDB
Optional messages about internal happenings
===========================================
`set debug arch'
Turns on or off display of gdbarch debugging info. The default is
off
`show debug arch'
Displays the current state of displaying gdbarch debugging info.
`set debug event'
Turns on or off display of GDB event debugging info. The default
is off.
`show debug event'
Displays the current state of displaying GDB event debugging info.
`set debug expression'
Turns on or off display of GDB expression debugging info. The
default is off.
`show debug expression'
Displays the current state of displaying GDB expression debugging
info.
`set debug frame'
Turns on or off display of GDB frame debugging info. The default
is off.
`show debug frame'
Displays the current state of displaying GDB frame debugging info.
`set debug overload'
Turns on or off display of GDB C++ overload debugging info. This
includes info such as ranking of functions, etc. The default is
off.
`show debug overload'
Displays the current state of displaying GDB C++ overload
debugging info.
`set debug remote'
Turns on or off display of reports on all packets sent back and
forth across the serial line to the remote machine. The info is
printed on the GDB standard output stream. The default is off.
`show debug remote'
Displays the state of display of remote packets.
`set debug serial'
Turns on or off display of GDB serial debugging info. The default
is off.
`show debug serial'
Displays the current state of displaying GDB serial debugging info.
`set debug target'
Turns on or off display of GDB target debugging info. This info
includes what is going on at the target level of GDB, as it
happens. The default is off.
`show debug target'
Displays the current state of displaying GDB target debugging info.
`set debug varobj'
Turns on or off display of GDB variable object debugging info. The
default is off.
`show debug varobj'
Displays the current state of displaying GDB variable object
debugging info.
File: gdb.info, Node: Sequences, Next: TUI, Prev: Controlling GDB, Up: Top
Canned Sequences of Commands
****************************
Aside from breakpoint commands (*note Breakpoint command lists: Break
Commands.), GDB provides two ways to store sequences of commands for
execution as a unit: user-defined commands and command files.
* Menu:
* Define:: User-defined commands
* Hooks:: User-defined command hooks
* Command Files:: Command files
* Output:: Commands for controlled output
File: gdb.info, Node: Define, Next: Hooks, Up: Sequences
User-defined commands
=====================
A "user-defined command" is a sequence of GDB commands to which you
assign a new name as a command. This is done with the `define'
command. User commands may accept up to 10 arguments separated by
whitespace. Arguments are accessed within the user command via
$ARG0...$ARG9. A trivial example:
define adder
print $arg0 + $arg1 + $arg2
To execute the command use:
adder 1 2 3
This defines the command `adder', which prints the sum of its three
arguments. Note the arguments are text substitutions, so they may
reference variables, use complex expressions, or even perform inferior
functions calls.
`define COMMANDNAME'
Define a command named COMMANDNAME. If there is already a command
by that name, you are asked to confirm that you want to redefine
it.
The definition of the command is made up of other GDB command
lines, which are given following the `define' command. The end of
these commands is marked by a line containing `end'.
`if'
Takes a single argument, which is an expression to evaluate. It
is followed by a series of commands that are executed only if the
expression is true (nonzero). There can then optionally be a line
`else', followed by a series of commands that are only executed if
the expression was false. The end of the list is marked by a line
containing `end'.
`while'
The syntax is similar to `if': the command takes a single argument,
which is an expression to evaluate, and must be followed by the
commands to execute, one per line, terminated by an `end'. The
commands are executed repeatedly as long as the expression
evaluates to true.
`document COMMANDNAME'
Document the user-defined command COMMANDNAME, so that it can be
accessed by `help'. The command COMMANDNAME must already be
defined. This command reads lines of documentation just as
`define' reads the lines of the command definition, ending with
`end'. After the `document' command is finished, `help' on command
COMMANDNAME displays the documentation you have written.
You may use the `document' command again to change the
documentation of a command. Redefining the command with `define'
does not change the documentation.
`help user-defined'
List all user-defined commands, with the first line of the
documentation (if any) for each.
`show user'
`show user COMMANDNAME'
Display the GDB commands used to define COMMANDNAME (but not its
documentation). If no COMMANDNAME is given, display the
definitions for all user-defined commands.
`show max-user-call-depth'
`set max-user-call-depth'
The value of `max-user-call-depth' controls how many recursion
levels are allowed in user-defined commands before GDB suspects an
infinite recursion and aborts the command.
When user-defined commands are executed, the commands of the
definition are not printed. An error in any command stops execution of
the user-defined command.
If used interactively, commands that would ask for confirmation
proceed without asking when used inside a user-defined command. Many
GDB commands that normally print messages to say what they are doing
omit the messages when used in a user-defined command.
File: gdb.info, Node: Hooks, Next: Command Files, Prev: Define, Up: Sequences
User-defined command hooks
==========================
You may define "hooks", which are a special kind of user-defined
command. Whenever you run the command `foo', if the user-defined
command `hook-foo' exists, it is executed (with no arguments) before
that command.
A hook may also be defined which is run after the command you
executed. Whenever you run the command `foo', if the user-defined
command `hookpost-foo' exists, it is executed (with no arguments) after
that command. Post-execution hooks may exist simultaneously with
pre-execution hooks, for the same command.
It is valid for a hook to call the command which it hooks. If this
occurs, the hook is not re-executed, thereby avoiding infinte recursion.
In addition, a pseudo-command, `stop' exists. Defining
(`hook-stop') makes the associated commands execute every time
execution stops in your program: before breakpoint commands are run,
displays are printed, or the stack frame is printed.
For example, to ignore `SIGALRM' signals while single-stepping, but
treat them normally during normal execution, you could define:
define hook-stop
handle SIGALRM nopass
end
define hook-run
handle SIGALRM pass
end
define hook-continue
handle SIGLARM pass
end
As a further example, to hook at the begining and end of the `echo'
command, and to add extra text to the beginning and end of the message,
you could define:
define hook-echo
echo <<<---
end
define hookpost-echo
echo --->>>\n
end
(gdb) echo Hello World
<<<---Hello World--->>>
(gdb)
You can define a hook for any single-word command in GDB, but not
for command aliases; you should define a hook for the basic command
name, e.g. `backtrace' rather than `bt'. If an error occurs during
the execution of your hook, execution of GDB commands stops and GDB
issues a prompt (before the command that you actually typed had a
chance to run).
If you try to define a hook which does not match any known command,
you get a warning from the `define' command.
File: gdb.info, Node: Command Files, Next: Output, Prev: Hooks, Up: Sequences
Command files
=============
A command file for GDB is a file of lines that are GDB commands.
Comments (lines starting with `#') may also be included. An empty line
in a command file does nothing; it does not mean to repeat the last
command, as it would from the terminal.
When you start GDB, it automatically executes commands from its
"init files", normally called `.gdbinit'(1). During startup, GDB does
the following:
1. Reads the init file (if any) in your home directory(2).
2. Processes command line options and operands.
3. Reads the init file (if any) in the current working directory.
4. Reads command files specified by the `-x' option.
The init file in your home directory can set options (such as `set
complaints') that affect subsequent processing of command line options
and operands. Init files are not executed if you use the `-nx' option
(*note Choosing modes: Mode Options.).
On some configurations of GDB, the init file is known by a different
name (these are typically environments where a specialized form of GDB
may need to coexist with other forms, hence a different name for the
specialized version's init file). These are the environments with
special init file names:
* VxWorks (Wind River Systems real-time OS): `.vxgdbinit'
* OS68K (Enea Data Systems real-time OS): `.os68gdbinit'
* ES-1800 (Ericsson Telecom AB M68000 emulator): `.esgdbinit'
You can also request the execution of a command file with the
`source' command:
`source FILENAME'
Execute the command file FILENAME.
The lines in a command file are executed sequentially. They are not
printed as they are executed. An error in any command terminates
execution of the command file and control is returned to the console.
Commands that would ask for confirmation if used interactively
proceed without asking when used in a command file. Many GDB commands
that normally print messages to say what they are doing omit the
messages when called from command files.
GDB also accepts command input from standard input. In this mode,
normal output goes to standard output and error output goes to standard
error. Errors in a command file supplied on standard input do not
terminate execution of the command file -- execution continues with the
next command.
gdb < cmds > log 2>&1
(The syntax above will vary depending on the shell used.) This
example will execute commands from the file `cmds'. All output and
errors would be directed to `log'.
---------- Footnotes ----------
(1) The DJGPP port of GDB uses the name `gdb.ini' instead, due to the
limitations of file names imposed by DOS filesystems.
(2) On DOS/Windows systems, the home directory is the one pointed to
by the `HOME' environment variable.
File: gdb.info, Node: Output, Prev: Command Files, Up: Sequences
Commands for controlled output
==============================
During the execution of a command file or a user-defined command, normal
GDB output is suppressed; the only output that appears is what is
explicitly printed by the commands in the definition. This section
describes three commands useful for generating exactly the output you
want.
`echo TEXT'
Print TEXT. Nonprinting characters can be included in TEXT using
C escape sequences, such as `\n' to print a newline. *No newline
is printed unless you specify one.* In addition to the standard C
escape sequences, a backslash followed by a space stands for a
space. This is useful for displaying a string with spaces at the
beginning or the end, since leading and trailing spaces are
otherwise trimmed from all arguments. To print ` and foo = ', use
the command `echo \ and foo = \ '.
A backslash at the end of TEXT can be used, as in C, to continue
the command onto subsequent lines. For example,
echo This is some text\n\
which is continued\n\
onto several lines.\n
produces the same output as
echo This is some text\n
echo which is continued\n
echo onto several lines.\n
`output EXPRESSION'
Print the value of EXPRESSION and nothing but that value: no
newlines, no `$NN = '. The value is not entered in the value
history either. *Note Expressions: Expressions, for more
information on expressions.
`output/FMT EXPRESSION'
Print the value of EXPRESSION in format FMT. You can use the same
formats as for `print'. *Note Output formats: Output Formats, for
more information.
`printf STRING, EXPRESSIONS...'
Print the values of the EXPRESSIONS under the control of STRING.
The EXPRESSIONS are separated by commas and may be either numbers
or pointers. Their values are printed as specified by STRING,
exactly as if your program were to execute the C subroutine
printf (STRING, EXPRESSIONS...);
For example, you can print two values in hex like this:
printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo
The only backslash-escape sequences that you can use in the format
string are the simple ones that consist of backslash followed by a
letter.
File: gdb.info, Node: Interpreters, Next: Emacs, Prev: TUI, Up: Top
Command Interpreters
********************
GDB supports multiple command interpreters, and some command
infrastructure to allow users or user interface writers to switch
between interpreters or run commands in other interpreters.
GDB currently supports two command interpreters, the console
interpreter (sometimes called the command-line interpreter or CLI) and
the machine interface interpreter (or GDB/MI). This manual describes
both of these interfaces in great detail.
By default, GDB will start with the console interpreter. However,
the user may choose to start GDB with another interpreter by specifying
the `-i' or `--interpreter' startup options. Defined interpreters
include:
`console'
The traditional console or command-line interpreter. This is the
most often used interpreter with GDB. With no interpreter
specified at runtime, GDB will use this interpreter.
`mi'
The newest GDB/MI interface (currently `mi2'). Used primarily by
programs wishing to use GDB as a backend for a debugger GUI or an
IDE. For more information, see *Note The GDB/MI Interface: GDB/MI.
`mi2'
The current GDB/MI interface.
`mi1'
The GDB/MI interface included in GDB 5.1, 5.2, and 5.3.
The interpreter being used by GDB may not be dynamically switched at
runtime. Although possible, this could lead to a very precarious
situation. Consider an IDE using GDB/MI. If a user enters the command
"interpreter-set console" in a console view, GDB would switch to using
the console interpreter, rendering the IDE inoperable!
Although you may only choose a single interpreter at startup, you
may execute commands in any interpreter from the current interpreter
using the appropriate command. If you are running the console
interpreter, simply use the `interpreter-exec' command:
interpreter-exec mi "-data-list-register-names"
GDB/MI has a similar command, although it is only available in
versions of GDB which support GDB/MI version 2 (or greater).
File: gdb.info, Node: TUI, Next: Interpreters, Prev: Sequences, Up: Top
GDB Text User Interface
***********************
* Menu:
* TUI Overview:: TUI overview
* TUI Keys:: TUI key bindings
* TUI Single Key Mode:: TUI single key mode
* TUI Commands:: TUI specific commands
* TUI Configuration:: TUI configuration variables
The GDB Text User Interface, TUI in short, is a terminal interface
which uses the `curses' library to show the source file, the assembly
output, the program registers and GDB commands in separate text windows.
The TUI is enabled by invoking GDB using either `gdbtui' or `gdb
-tui'.
File: gdb.info, Node: TUI Overview, Next: TUI Keys, Up: TUI
TUI overview
============
The TUI has two display modes that can be switched while GDB runs:
* A curses (or TUI) mode in which it displays several text windows
on the terminal.
* A standard mode which corresponds to the GDB configured without
the TUI.
In the TUI mode, GDB can display several text window on the terminal:
_command_
This window is the GDB command window with the GDB prompt and the
GDB outputs. The GDB input is still managed using readline but
through the TUI. The _command_ window is always visible.
_source_
The source window shows the source file of the program. The
current line as well as active breakpoints are displayed in this
window.
_assembly_
The assembly window shows the disassembly output of the program.
_register_
This window shows the processor registers. It detects when a
register is changed and when this is the case, registers that have
changed are highlighted.
The source and assembly windows show the current program position by
highlighting the current line and marking them with the `>' marker.
Breakpoints are also indicated with two markers. A first one indicates
the breakpoint type:
`B'
Breakpoint which was hit at least once.
`b'
Breakpoint which was never hit.
`H'
Hardware breakpoint which was hit at least once.
`h'
Hardware breakpoint which was never hit.
The second marker indicates whether the breakpoint is enabled or not:
`+'
Breakpoint is enabled.
`-'
Breakpoint is disabled.
The source, assembly and register windows are attached to the thread
and the frame position. They are updated when the current thread
changes, when the frame changes or when the program counter changes.
These three windows are arranged by the TUI according to several
layouts. The layout defines which of these three windows are visible.
The following layouts are available:
* source
* assembly
* source and assembly
* source and registers
* assembly and registers
On top of the command window a status line gives various information
concerning the current process begin debugged. The status line is
updated when the information it shows changes. The following fields
are displayed:
_target_
Indicates the current gdb target (*note Specifying a Debugging
Target: Targets.).
_process_
Gives information about the current process or thread number.
When no process is being debugged, this field is set to `No
process'.
_function_
Gives the current function name for the selected frame. The name
is demangled if demangling is turned on (*note Print Settings::).
When there is no symbol corresponding to the current program
counter the string `??' is displayed.
_line_
Indicates the current line number for the selected frame. When
the current line number is not known the string `??' is displayed.
_pc_
Indicates the current program counter address.
File: gdb.info, Node: TUI Keys, Next: TUI Single Key Mode, Prev: TUI Overview, Up: TUI
TUI Key Bindings
================
The TUI installs several key bindings in the readline keymaps (*note
Command Line Editing::). They allow to leave or enter in the TUI mode
or they operate directly on the TUI layout and windows. The TUI also
provides a _SingleKey_ keymap which binds several keys directly to GDB
commands. The following key bindings are installed for both TUI mode
and the GDB standard mode.
`C-x C-a'
`C-x a'
`C-x A'
Enter or leave the TUI mode. When the TUI mode is left, the
curses window management is left and GDB operates using its
standard mode writing on the terminal directly. When the TUI mode
is entered, the control is given back to the curses windows. The
screen is then refreshed.
`C-x 1'
Use a TUI layout with only one window. The layout will either be
`source' or `assembly'. When the TUI mode is not active, it will
switch to the TUI mode.
Think of this key binding as the Emacs `C-x 1' binding.
`C-x 2'
Use a TUI layout with at least two windows. When the current
layout shows already two windows, a next layout with two windows
is used. When a new layout is chosen, one window will always be
common to the previous layout and the new one.
Think of it as the Emacs `C-x 2' binding.
`C-x o'
Change the active window. The TUI associates several key bindings
(like scrolling and arrow keys) to the active window. This command
gives the focus to the next TUI window.
Think of it as the Emacs `C-x o' binding.
`C-x s'
Use the TUI _SingleKey_ keymap that binds single key to gdb
commands (*note TUI Single Key Mode::).
The following key bindings are handled only by the TUI mode:
<PgUp>
Scroll the active window one page up.
<PgDn>
Scroll the active window one page down.
<Up>
Scroll the active window one line up.
<Down>
Scroll the active window one line down.
<Left>
Scroll the active window one column left.
<Right>
Scroll the active window one column right.
<C-L>
Refresh the screen.
In the TUI mode, the arrow keys are used by the active window for
scrolling. This means they are available for readline when the active
window is the command window. When the command window does not have
the focus, it is necessary to use other readline key bindings such as
<C-p>, <C-n>, <C-b> and <C-f>.
File: gdb.info, Node: TUI Single Key Mode, Next: TUI Commands, Prev: TUI Keys, Up: TUI
TUI Single Key Mode
===================
The TUI provides a _SingleKey_ mode in which it installs a particular
key binding in the readline keymaps to connect single keys to some gdb
commands.
`c'
continue
`d'
down
`f'
finish
`n'
next
`q'
exit the _SingleKey_ mode.
`r'
run
`s'
step
`u'
up
`v'
info locals
`w'
where
Other keys temporarily switch to the GDB command prompt. The key
that was pressed is inserted in the editing buffer so that it is
possible to type most GDB commands without interaction with the TUI
_SingleKey_ mode. Once the command is entered the TUI _SingleKey_ mode
is restored. The only way to permanently leave this mode is by hitting
<q> or `<C-x> <s>'.
File: gdb.info, Node: TUI Commands, Next: TUI Configuration, Prev: TUI Single Key Mode, Up: TUI
TUI specific commands
=====================
The TUI has specific commands to control the text windows. These
commands are always available, that is they do not depend on the
current terminal mode in which GDB runs. When GDB is in the standard
mode, using these commands will automatically switch in the TUI mode.
`info win'
List and give the size of all displayed windows.
`layout next'
Display the next layout.
`layout prev'
Display the previous layout.
`layout src'
Display the source window only.
`layout asm'
Display the assembly window only.
`layout split'
Display the source and assembly window.
`layout regs'
Display the register window together with the source or assembly
window.
`focus next | prev | src | asm | regs | split'
Set the focus to the named window. This command allows to change
the active window so that scrolling keys can be affected to
another window.
`refresh'
Refresh the screen. This is similar to using <C-L> key.
`tui reg float'
Show the floating point registers in the register window.
`tui reg general'
Show the general registers in the register window.
`tui reg next'
Show the next register group. The list of register groups as well
as their order is target specific. The predefined register groups
are the following: `general', `float', `system', `vector', `all',
`save', `restore'.
`tui reg system'
Show the system registers in the register window.
`update'
Update the source window and the current execution point.
`winheight NAME +COUNT'
`winheight NAME -COUNT'
Change the height of the window NAME by COUNT lines. Positive
counts increase the height, while negative counts decrease it.
File: gdb.info, Node: TUI Configuration, Prev: TUI Commands, Up: TUI
TUI configuration variables
===========================
The TUI has several configuration variables that control the appearance
of windows on the terminal.
`set tui border-kind KIND'
Select the border appearance for the source, assembly and register
windows. The possible values are the following:
`space'
Use a space character to draw the border.
`ascii'
Use ascii characters + - and | to draw the border.
`acs'
Use the Alternate Character Set to draw the border. The
border is drawn using character line graphics if the terminal
supports them.
`set tui active-border-mode MODE'
Select the attributes to display the border of the active window.
The possible values are `normal', `standout', `reverse', `half',
`half-standout', `bold' and `bold-standout'.
`set tui border-mode MODE'
Select the attributes to display the border of other windows. The
MODE can be one of the following:
`normal'
Use normal attributes to display the border.
`standout'
Use standout mode.
`reverse'
Use reverse video mode.
`half'
Use half bright mode.
`half-standout'
Use half bright and standout mode.
`bold'
Use extra bright or bold mode.
`bold-standout'
Use extra bright or bold and standout mode.
File: gdb.info, Node: Emacs, Next: Annotations, Prev: Interpreters, Up: Top
Using GDB under GNU Emacs
*************************
A special interface allows you to use GNU Emacs to view (and edit) the
source files for the program you are debugging with GDB.
To use this interface, use the command `M-x gdb' in Emacs. Give the
executable file you want to debug as an argument. This command starts
GDB as a subprocess of Emacs, with input and output through a newly
created Emacs buffer.
Using GDB under Emacs is just like using GDB normally except for two
things:
* All "terminal" input and output goes through the Emacs buffer.
This applies both to GDB commands and their output, and to the input
and output done by the program you are debugging.
This is useful because it means that you can copy the text of
previous commands and input them again; you can even use parts of the
output in this way.
All the facilities of Emacs' Shell mode are available for interacting
with your program. In particular, you can send signals the usual
way--for example, `C-c C-c' for an interrupt, `C-c C-z' for a stop.
* GDB displays source code through Emacs.
Each time GDB displays a stack frame, Emacs automatically finds the
source file for that frame and puts an arrow (`=>') at the left margin
of the current line. Emacs uses a separate buffer for source display,
and splits the screen to show both your GDB session and the source.
Explicit GDB `list' or search commands still produce output as
usual, but you probably have no reason to use them from Emacs.
If you specify an absolute file name when prompted for the `M-x gdb'
argument, then Emacs sets your current working directory to where your
program resides. If you only specify the file name, then Emacs sets
your current working directory to to the directory associated with the
previous buffer. In this case, GDB may find your program by searching
your environment's `PATH' variable, but on some operating systems it
might not find the source. So, although the GDB input and output
session proceeds normally, the auxiliary buffer does not display the
current source and line of execution.
The initial working directory of GDB is printed on the top line of
the GDB I/O buffer and this serves as a default for the commands that
specify files for GDB to operate on. *Note Commands to specify files:
Files.
By default, `M-x gdb' calls the program called `gdb'. If you need
to call GDB by a different name (for example, if you keep several
configurations around, with different names) you can customize the
Emacs variable `gud-gdb-command-name' to run the one you want.
In the GDB I/O buffer, you can use these special Emacs commands in
addition to the standard Shell mode commands:
`C-h m'
Describe the features of Emacs' GDB Mode.
`C-c C-s'
Execute to another source line, like the GDB `step' command; also
update the display window to show the current file and location.
`C-c C-n'
Execute to next source line in this function, skipping all function
calls, like the GDB `next' command. Then update the display window
to show the current file and location.
`C-c C-i'
Execute one instruction, like the GDB `stepi' command; update
display window accordingly.
`C-c C-f'
Execute until exit from the selected stack frame, like the GDB
`finish' command.
`C-c C-r'
Continue execution of your program, like the GDB `continue'
command.
`C-c <'
Go up the number of frames indicated by the numeric argument
(*note Numeric Arguments: (Emacs)Arguments.), like the GDB `up'
command.
`C-c >'
Go down the number of frames indicated by the numeric argument,
like the GDB `down' command.
In any source file, the Emacs command `C-x SPC' (`gud-break') tells
GDB to set a breakpoint on the source line point is on.
If you type `M-x speedbar', then Emacs displays a separate frame
which shows a backtrace when the GDB I/O buffer is current. Move point
to any frame in the stack and type <RET> to make it become the current
frame and display the associated source in the source buffer.
Alternatively, click `Mouse-2' to make the selected frame become the
current one.
If you accidentally delete the source-display buffer, an easy way to
get it back is to type the command `f' in the GDB buffer, to request a
frame display; when you run under Emacs, this recreates the source
buffer if necessary to show you the context of the current frame.
The source files displayed in Emacs are in ordinary Emacs buffers
which are visiting the source files in the usual way. You can edit the
files with these buffers if you wish; but keep in mind that GDB
communicates with Emacs in terms of line numbers. If you add or delete
lines from the text, the line numbers that GDB knows cease to
correspond properly with the code.
The description given here is for GNU Emacs version 21.3 and a more
detailed description of its interaction with GDB is given in the Emacs
manual (*note Debuggers: (Emacs)Debuggers.).
File: gdb.info, Node: GDB/MI, Next: GDB Bugs, Prev: Annotations, Up: Top
The GDB/MI Interface
********************
Function and Purpose
====================
GDB/MI is a line based machine oriented text interface to GDB. It is
specifically intended to support the development of systems which use
the debugger as just one small component of a larger system.
This chapter is a specification of the GDB/MI interface. It is
written in the form of a reference manual.
Note that GDB/MI is still under construction, so some of the
features described below are incomplete and subject to change.
Notation and Terminology
========================
This chapter uses the following notation:
* `|' separates two alternatives.
* `[ SOMETHING ]' indicates that SOMETHING is optional: it may or
may not be given.
* `( GROUP )*' means that GROUP inside the parentheses may repeat
zero or more times.
* `( GROUP )+' means that GROUP inside the parentheses may repeat
one or more times.
* `"STRING"' means a literal STRING.
Acknowledgments
===============
In alphabetic order: Andrew Cagney, Fernando Nasser, Stan Shebs and
Elena Zannoni.
* Menu:
* GDB/MI Command Syntax::
* GDB/MI Compatibility with CLI::
* GDB/MI Output Records::
* GDB/MI Command Description Format::
* GDB/MI Breakpoint Table Commands::
* GDB/MI Data Manipulation::
* GDB/MI Program Control::
* GDB/MI Miscellaneous Commands::
* GDB/MI Stack Manipulation::
* GDB/MI Symbol Query::
* GDB/MI Target Manipulation::
* GDB/MI Thread Commands::
* GDB/MI Tracepoint Commands::
* GDB/MI Variable Objects::
File: gdb.info, Node: GDB/MI Command Syntax, Next: GDB/MI Compatibility with CLI, Up: GDB/MI
GDB/MI Command Syntax
=====================
* Menu:
* GDB/MI Input Syntax::
* GDB/MI Output Syntax::
* GDB/MI Simple Examples::
File: gdb.info, Node: GDB/MI Input Syntax, Next: GDB/MI Output Syntax, Up: GDB/MI Command Syntax
GDB/MI Input Syntax
-------------------
`COMMAND ==>'
`CLI-COMMAND | MI-COMMAND'
`CLI-COMMAND ==>'
`[ TOKEN ] CLI-COMMAND NL', where CLI-COMMAND is any existing GDB
CLI command.
`MI-COMMAND ==>'
`[ TOKEN ] "-" OPERATION ( " " OPTION )* `[' " --" `]' ( " "
PARAMETER )* NL'
`TOKEN ==>'
"any sequence of digits"
`OPTION ==>'
`"-" PARAMETER [ " " PARAMETER ]'
`PARAMETER ==>'
`NON-BLANK-SEQUENCE | C-STRING'
`OPERATION ==>'
_any of the operations described in this chapter_
`NON-BLANK-SEQUENCE ==>'
_anything, provided it doesn't contain special characters such as
"-", NL, """ and of course " "_
`C-STRING ==>'
`""" SEVEN-BIT-ISO-C-STRING-CONTENT """'
`NL ==>'
`CR | CR-LF'
Notes:
* The CLI commands are still handled by the MI interpreter; their
output is described below.
* The `TOKEN', when present, is passed back when the command
finishes.
* Some MI commands accept optional arguments as part of the parameter
list. Each option is identified by a leading `-' (dash) and may be
followed by an optional argument parameter. Options occur first
in the parameter list and can be delimited from normal parameters
using `--' (this is useful when some parameters begin with a dash).
Pragmatics:
* We want easy access to the existing CLI syntax (for debugging).
* We want it to be easy to spot a MI operation.
File: gdb.info, Node: GDB/MI Output Syntax, Next: GDB/MI Simple Examples, Prev: GDB/MI Input Syntax, Up: GDB/MI Command Syntax
GDB/MI Output Syntax
--------------------
The output from GDB/MI consists of zero or more out-of-band records
followed, optionally, by a single result record. This result record is
for the most recent command. The sequence of output records is
terminated by `(gdb)'.
If an input command was prefixed with a `TOKEN' then the
corresponding output for that command will also be prefixed by that same
TOKEN.
`OUTPUT ==>'
`( OUT-OF-BAND-RECORD )* [ RESULT-RECORD ] "(gdb)" NL'
`RESULT-RECORD ==>'
` [ TOKEN ] "^" RESULT-CLASS ( "," RESULT )* NL'
`OUT-OF-BAND-RECORD ==>'
`ASYNC-RECORD | STREAM-RECORD'
`ASYNC-RECORD ==>'
`EXEC-ASYNC-OUTPUT | STATUS-ASYNC-OUTPUT | NOTIFY-ASYNC-OUTPUT'
`EXEC-ASYNC-OUTPUT ==>'
`[ TOKEN ] "*" ASYNC-OUTPUT'
`STATUS-ASYNC-OUTPUT ==>'
`[ TOKEN ] "+" ASYNC-OUTPUT'
`NOTIFY-ASYNC-OUTPUT ==>'
`[ TOKEN ] "=" ASYNC-OUTPUT'
`ASYNC-OUTPUT ==>'
`ASYNC-CLASS ( "," RESULT )* NL'
`RESULT-CLASS ==>'
`"done" | "running" | "connected" | "error" | "exit"'
`ASYNC-CLASS ==>'
`"stopped" | OTHERS' (where OTHERS will be added depending on the
needs--this is still in development).
`RESULT ==>'
` VARIABLE "=" VALUE'
`VARIABLE ==>'
` STRING '
`VALUE ==>'
` CONST | TUPLE | LIST '
`CONST ==>'
`C-STRING'
`TUPLE ==>'
` "{}" | "{" RESULT ( "," RESULT )* "}" '
`LIST ==>'
` "[]" | "[" VALUE ( "," VALUE )* "]" | "[" RESULT ( "," RESULT )*
"]" '
`STREAM-RECORD ==>'
`CONSOLE-STREAM-OUTPUT | TARGET-STREAM-OUTPUT | LOG-STREAM-OUTPUT'
`CONSOLE-STREAM-OUTPUT ==>'
`"~" C-STRING'
`TARGET-STREAM-OUTPUT ==>'
`"@" C-STRING'
`LOG-STREAM-OUTPUT ==>'
`"&" C-STRING'
`NL ==>'
`CR | CR-LF'
`TOKEN ==>'
_any sequence of digits_.
Notes:
* All output sequences end in a single line containing a period.
* The `TOKEN' is from the corresponding request. If an execution
command is interrupted by the `-exec-interrupt' command, the TOKEN
associated with the `*stopped' message is the one of the original
execution command, not the one of the interrupt command.
* STATUS-ASYNC-OUTPUT contains on-going status information about the
progress of a slow operation. It can be discarded. All status
output is prefixed by `+'.
* EXEC-ASYNC-OUTPUT contains asynchronous state change on the target
(stopped, started, disappeared). All async output is prefixed by
`*'.
* NOTIFY-ASYNC-OUTPUT contains supplementary information that the
client should handle (e.g., a new breakpoint information). All
notify output is prefixed by `='.
* CONSOLE-STREAM-OUTPUT is output that should be displayed as is in
the console. It is the textual response to a CLI command. All
the console output is prefixed by `~'.
* TARGET-STREAM-OUTPUT is the output produced by the target program.
All the target output is prefixed by `@'.
* LOG-STREAM-OUTPUT is output text coming from GDB's internals, for
instance messages that should be displayed as part of an error
log. All the log output is prefixed by `&'.
* New GDB/MI commands should only output LISTS containing VALUES.
*Note GDB/MI Stream Records: GDB/MI Stream Records, for more details
about the various output records.
File: gdb.info, Node: GDB/MI Simple Examples, Prev: GDB/MI Output Syntax, Up: GDB/MI Command Syntax
Simple Examples of GDB/MI Interaction
-------------------------------------
This subsection presents several simple examples of interaction using
the GDB/MI interface. In these examples, `->' means that the following
line is passed to GDB/MI as input, while `<-' means the output received
from GDB/MI.
Target Stop
...........
Here's an example of stopping the inferior process:
-> -stop
<- (gdb)
and later:
<- *stop,reason="stop",address="0x123",source="a.c:123"
<- (gdb)
Simple CLI Command
..................
Here's an example of a simple CLI command being passed through GDB/MI
and on to the CLI.
-> print 1+2
<- &"print 1+2\n"
<- ~"$1 = 3\n"
<- ^done
<- (gdb)
Command With Side Effects
.........................
-> -symbol-file xyz.exe
<- *breakpoint,nr="3",address="0x123",source="a.c:123"
<- (gdb)
A Bad Command
.............
Here's what happens if you pass a non-existent command:
-> -rubbish
<- ^error,msg="Undefined MI command: rubbish"
<- (gdb)
File: gdb.info, Node: GDB/MI Compatibility with CLI, Next: GDB/MI Output Records, Prev: GDB/MI Command Syntax, Up: GDB/MI
GDB/MI Compatibility with CLI
=============================
To help users familiar with GDB's existing CLI interface, GDB/MI
accepts existing CLI commands. As specified by the syntax, such
commands can be directly entered into the GDB/MI interface and GDB will
respond.
This mechanism is provided as an aid to developers of GDB/MI clients
and not as a reliable interface into the CLI. Since the command is
being interpreteted in an environment that assumes GDB/MI behaviour,
the exact output of such commands is likely to end up being an
un-supported hybrid of GDB/MI and CLI output.
File: gdb.info, Node: GDB/MI Output Records, Next: GDB/MI Command Description Format, Prev: GDB/MI Compatibility with CLI, Up: GDB/MI
GDB/MI Output Records
=====================
* Menu:
* GDB/MI Result Records::
* GDB/MI Stream Records::
* GDB/MI Out-of-band Records::
File: gdb.info, Node: GDB/MI Result Records, Next: GDB/MI Stream Records, Up: GDB/MI Output Records
GDB/MI Result Records
---------------------
In addition to a number of out-of-band notifications, the response to a
GDB/MI command includes one of the following result indications:
`"^done" [ "," RESULTS ]'
The synchronous operation was successful, `RESULTS' are the return
values.
`"^running"'
The asynchronous operation was successfully started. The target is
running.
`"^error" "," C-STRING'
The operation failed. The `C-STRING' contains the corresponding
error message.
File: gdb.info, Node: GDB/MI Stream Records, Next: GDB/MI Out-of-band Records, Prev: GDB/MI Result Records, Up: GDB/MI Output Records
GDB/MI Stream Records
---------------------
GDB internally maintains a number of output streams: the console, the
target, and the log. The output intended for each of these streams is
funneled through the GDB/MI interface using "stream records".
Each stream record begins with a unique "prefix character" which
identifies its stream (*note GDB/MI Output Syntax: GDB/MI Output
Syntax.). In addition to the prefix, each stream record contains a
`STRING-OUTPUT'. This is either raw text (with an implicit new line)
or a quoted C string (which does not contain an implicit newline).
`"~" STRING-OUTPUT'
The console output stream contains text that should be displayed
in the CLI console window. It contains the textual responses to
CLI commands.
`"@" STRING-OUTPUT'
The target output stream contains any textual output from the
running target.
`"&" STRING-OUTPUT'
The log stream contains debugging messages being produced by GDB's
internals.
File: gdb.info, Node: GDB/MI Out-of-band Records, Prev: GDB/MI Stream Records, Up: GDB/MI Output Records
GDB/MI Out-of-band Records
--------------------------
"Out-of-band" records are used to notify the GDB/MI client of
additional changes that have occurred. Those changes can either be a
consequence of GDB/MI (e.g., a breakpoint modified) or a result of
target activity (e.g., target stopped).
The following is a preliminary list of possible out-of-band records.
`"*" "stop"'
File: gdb.info, Node: GDB/MI Command Description Format, Next: GDB/MI Breakpoint Table Commands, Prev: GDB/MI Output Records, Up: GDB/MI
GDB/MI Command Description Format
=================================
The remaining sections describe blocks of commands. Each block of
commands is laid out in a fashion similar to this section.
Note the the line breaks shown in the examples are here only for
readability. They don't appear in the real output. Also note that the
commands with a non-available example (N.A.) are not yet implemented.
Motivation
----------
The motivation for this collection of commands.
Introduction
------------
A brief introduction to this collection of commands as a whole.
Commands
--------
For each command in the block, the following is described:
Synopsis
........
-command ARGS...
GDB Command
...........
The corresponding GDB CLI command.
Result
......
Out-of-band
...........
Notes
.....
Example
.......
File: gdb.info, Node: GDB/MI Breakpoint Table Commands, Next: GDB/MI Data Manipulation, Prev: GDB/MI Command Description Format, Up: GDB/MI
GDB/MI Breakpoint table commands
================================
This section documents GDB/MI commands for manipulating breakpoints.
The `-break-after' Command
--------------------------
Synopsis
........
-break-after NUMBER COUNT
The breakpoint number NUMBER is not in effect until it has been hit
COUNT times. To see how this is reflected in the output of the
`-break-list' command, see the description of the `-break-list' command
below.
GDB Command
...........
The corresponding GDB command is `ignore'.
Example
.......
(gdb)
-break-insert main
^done,bkpt={number="1",addr="0x000100d0",file="hello.c",line="5"}
(gdb)
-break-after 1 3
~
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x000100d0",func="main",file="hello.c",line="5",times="0",
ignore="3"}]}
(gdb)
The `-break-condition' Command
------------------------------
Synopsis
........
-break-condition NUMBER EXPR
Breakpoint NUMBER will stop the program only if the condition in
EXPR is true. The condition becomes part of the `-break-list' output
(see the description of the `-break-list' command below).
GDB Command
...........
The corresponding GDB command is `condition'.
Example
.......
(gdb)
-break-condition 1 1
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x000100d0",func="main",file="hello.c",line="5",cond="1",
times="0",ignore="3"}]}
(gdb)
The `-break-delete' Command
---------------------------
Synopsis
........
-break-delete ( BREAKPOINT )+
Delete the breakpoint(s) whose number(s) are specified in the
argument list. This is obviously reflected in the breakpoint list.
GDB command
...........
The corresponding GDB command is `delete'.
Example
.......
(gdb)
-break-delete 1
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="0",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[]}
(gdb)
The `-break-disable' Command
----------------------------
Synopsis
........
-break-disable ( BREAKPOINT )+
Disable the named BREAKPOINT(s). The field `enabled' in the break
list is now set to `n' for the named BREAKPOINT(s).
GDB Command
...........
The corresponding GDB command is `disable'.
Example
.......
(gdb)
-break-disable 2
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="n",
addr="0x000100d0",func="main",file="hello.c",line="5",times="0"}]}
(gdb)
The `-break-enable' Command
---------------------------
Synopsis
........
-break-enable ( BREAKPOINT )+
Enable (previously disabled) BREAKPOINT(s).
GDB Command
...........
The corresponding GDB command is `enable'.
Example
.......
(gdb)
-break-enable 2
^done
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="2",type="breakpoint",disp="keep",enabled="y",
addr="0x000100d0",func="main",file="hello.c",line="5",times="0"}]}
(gdb)
The `-break-info' Command
-------------------------
Synopsis
........
-break-info BREAKPOINT
Get information about a single breakpoint.
GDB command
...........
The corresponding GDB command is `info break BREAKPOINT'.
Example
.......
N.A.
The `-break-insert' Command
---------------------------
Synopsis
........
-break-insert [ -t ] [ -h ] [ -r ]
[ -c CONDITION ] [ -i IGNORE-COUNT ]
[ -p THREAD ] [ LINE | ADDR ]
If specified, LINE, can be one of:
* function
* filename:linenum
* filename:function
* *address
The possible optional parameters of this command are:
`-t'
Insert a tempoary breakpoint.
`-h'
Insert a hardware breakpoint.
`-c CONDITION'
Make the breakpoint conditional on CONDITION.
`-i IGNORE-COUNT'
Initialize the IGNORE-COUNT.
`-r'
Insert a regular breakpoint in all the functions whose names match
the given regular expression. Other flags are not applicable to
regular expresson.
Result
......
The result is in the form:
^done,bkptno="NUMBER",func="FUNCNAME",
file="FILENAME",line="LINENO"
where NUMBER is the GDB number for this breakpoint, FUNCNAME is the
name of the function where the breakpoint was inserted, FILENAME is the
name of the source file which contains this function, and LINENO is the
source line number within that file.
Note: this format is open to change.
GDB Command
...........
The corresponding GDB commands are `break', `tbreak', `hbreak',
`thbreak', and `rbreak'.
Example
.......
(gdb)
-break-insert main
^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c",line="4"}
(gdb)
-break-insert -t foo
^done,bkpt={number="2",addr="0x00010774",file="recursive2.c",line="11"}
(gdb)
-break-list
^done,BreakpointTable={nr_rows="2",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x0001072c", func="main",file="recursive2.c",line="4",times="0"},
bkpt={number="2",type="breakpoint",disp="del",enabled="y",
addr="0x00010774",func="foo",file="recursive2.c",line="11",times="0"}]}
(gdb)
-break-insert -r foo.*
~int foo(int, int);
^done,bkpt={number="3",addr="0x00010774",file="recursive2.c",line="11"}
(gdb)
The `-break-list' Command
-------------------------
Synopsis
........
-break-list
Displays the list of inserted breakpoints, showing the following
fields:
`Number'
number of the breakpoint
`Type'
type of the breakpoint: `breakpoint' or `watchpoint'
`Disposition'
should the breakpoint be deleted or disabled when it is hit: `keep'
or `nokeep'
`Enabled'
is the breakpoint enabled or no: `y' or `n'
`Address'
memory location at which the breakpoint is set
`What'
logical location of the breakpoint, expressed by function name,
file name, line number
`Times'
number of times the breakpoint has been hit
If there are no breakpoints or watchpoints, the `BreakpointTable'
`body' field is an empty list.
GDB Command
...........
The corresponding GDB command is `info break'.
Example
.......
(gdb)
-break-list
^done,BreakpointTable={nr_rows="2",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x000100d0",func="main",file="hello.c",line="5",times="0"},
bkpt={number="2",type="breakpoint",disp="keep",enabled="y",
addr="0x00010114",func="foo",file="hello.c",line="13",times="0"}]}
(gdb)
Here's an example of the result when there are no breakpoints:
(gdb)
-break-list
^done,BreakpointTable={nr_rows="0",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[]}
(gdb)
The `-break-watch' Command
--------------------------
Synopsis
........
-break-watch [ -a | -r ]
Create a watchpoint. With the `-a' option it will create an
"access" watchpoint, i.e. a watchpoint that triggers either on a read
from or on a write to the memory location. With the `-r' option, the
watchpoint created is a "read" watchpoint, i.e. it will trigger only
when the memory location is accessed for reading. Without either of
the options, the watchpoint created is a regular watchpoint, i.e. it
will trigger when the memory location is accessed for writing. *Note
Setting watchpoints: Set Watchpoints.
Note that `-break-list' will report a single list of watchpoints and
breakpoints inserted.
GDB Command
...........
The corresponding GDB commands are `watch', `awatch', and `rwatch'.
Example
.......
Setting a watchpoint on a variable in the `main' function:
(gdb)
-break-watch x
^done,wpt={number="2",exp="x"}
(gdb)
-exec-continue
^running
^done,reason="watchpoint-trigger",wpt={number="2",exp="x"},
value={old="-268439212",new="55"},
frame={func="main",args=[],file="recursive2.c",line="5"}
(gdb)
Setting a watchpoint on a variable local to a function. GDB will
stop the program execution twice: first for the variable changing
value, then for the watchpoint going out of scope.
(gdb)
-break-watch C
^done,wpt={number="5",exp="C"}
(gdb)
-exec-continue
^running
^done,reason="watchpoint-trigger",
wpt={number="5",exp="C"},value={old="-276895068",new="3"},
frame={func="callee4",args=[],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="13"}
(gdb)
-exec-continue
^running
^done,reason="watchpoint-scope",wpnum="5",
frame={func="callee3",args=[{name="strarg",
value="0x11940 \"A string argument.\""}],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
(gdb)
Listing breakpoints and watchpoints, at different points in the
program execution. Note that once the watchpoint goes out of scope, it
is deleted.
(gdb)
-break-watch C
^done,wpt={number="2",exp="C"}
(gdb)
-break-list
^done,BreakpointTable={nr_rows="2",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x00010734",func="callee4",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"},
bkpt={number="2",type="watchpoint",disp="keep",
enabled="y",addr="",what="C",times="0"}]}
(gdb)
-exec-continue
^running
^done,reason="watchpoint-trigger",wpt={number="2",exp="C"},
value={old="-276895068",new="3"},
frame={func="callee4",args=[],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="13"}
(gdb)
-break-list
^done,BreakpointTable={nr_rows="2",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x00010734",func="callee4",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"},
bkpt={number="2",type="watchpoint",disp="keep",
enabled="y",addr="",what="C",times="-5"}]}
(gdb)
-exec-continue
^running
^done,reason="watchpoint-scope",wpnum="2",
frame={func="callee3",args=[{name="strarg",
value="0x11940 \"A string argument.\""}],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
(gdb)
-break-list
^done,BreakpointTable={nr_rows="1",nr_cols="6",
hdr=[{width="3",alignment="-1",col_name="number",colhdr="Num"},
{width="14",alignment="-1",col_name="type",colhdr="Type"},
{width="4",alignment="-1",col_name="disp",colhdr="Disp"},
{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},
{width="10",alignment="-1",col_name="addr",colhdr="Address"},
{width="40",alignment="2",col_name="what",colhdr="What"}],
body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",
addr="0x00010734",func="callee4",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8",times="1"}]}
(gdb)
File: gdb.info, Node: GDB/MI Data Manipulation, Next: GDB/MI Program Control, Prev: GDB/MI Breakpoint Table Commands, Up: GDB/MI
GDB/MI Data Manipulation
========================
This section describes the GDB/MI commands that manipulate data:
examine memory and registers, evaluate expressions, etc.
The `-data-disassemble' Command
-------------------------------
Synopsis
........
-data-disassemble
[ -s START-ADDR -e END-ADDR ]
| [ -f FILENAME -l LINENUM [ -n LINES ] ]
-- MODE
Where:
`START-ADDR'
is the beginning address (or `$pc')
`END-ADDR'
is the end address
`FILENAME'
is the name of the file to disassemble
`LINENUM'
is the line number to disassemble around
`LINES'
is the the number of disassembly lines to be produced. If it is
-1, the whole function will be disassembled, in case no END-ADDR is
specified. If END-ADDR is specified as a non-zero value, and
LINES is lower than the number of disassembly lines between
START-ADDR and END-ADDR, only LINES lines are displayed; if LINES
is higher than the number of lines between START-ADDR and
END-ADDR, only the lines up to END-ADDR are displayed.
`MODE'
is either 0 (meaning only disassembly) or 1 (meaning mixed source
and disassembly).
Result
......
The output for each instruction is composed of four fields:
* Address
* Func-name
* Offset
* Instruction
Note that whatever included in the instruction field, is not
manipulated directely by GDB/MI, i.e. it is not possible to adjust its
format.
GDB Command
...........
There's no direct mapping from this command to the CLI.
Example
.......
Disassemble from the current value of `$pc' to `$pc + 20':
(gdb)
-data-disassemble -s $pc -e "$pc + 20" -- 0
^done,
asm_insns=[
{address="0x000107c0",func-name="main",offset="4",
inst="mov 2, %o0"},
{address="0x000107c4",func-name="main",offset="8",
inst="sethi %hi(0x11800), %o2"},
{address="0x000107c8",func-name="main",offset="12",
inst="or %o2, 0x140, %o1\t! 0x11940 <_lib_version+8>"},
{address="0x000107cc",func-name="main",offset="16",
inst="sethi %hi(0x11800), %o2"},
{address="0x000107d0",func-name="main",offset="20",
inst="or %o2, 0x168, %o4\t! 0x11968 <_lib_version+48>"}]
(gdb)
Disassemble the whole `main' function. Line 32 is part of `main'.
-data-disassemble -f basics.c -l 32 -- 0
^done,asm_insns=[
{address="0x000107bc",func-name="main",offset="0",
inst="save %sp, -112, %sp"},
{address="0x000107c0",func-name="main",offset="4",
inst="mov 2, %o0"},
{address="0x000107c4",func-name="main",offset="8",
inst="sethi %hi(0x11800), %o2"},
[...]
{address="0x0001081c",func-name="main",offset="96",inst="ret "},
{address="0x00010820",func-name="main",offset="100",inst="restore "}]
(gdb)
Disassemble 3 instructions from the start of `main':
(gdb)
-data-disassemble -f basics.c -l 32 -n 3 -- 0
^done,asm_insns=[
{address="0x000107bc",func-name="main",offset="0",
inst="save %sp, -112, %sp"},
{address="0x000107c0",func-name="main",offset="4",
inst="mov 2, %o0"},
{address="0x000107c4",func-name="main",offset="8",
inst="sethi %hi(0x11800), %o2"}]
(gdb)
Disassemble 3 instructions from the start of `main' in mixed mode:
(gdb)
-data-disassemble -f basics.c -l 32 -n 3 -- 1
^done,asm_insns=[
src_and_asm_line={line="31",
file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \
testsuite/gdb.mi/basics.c",line_asm_insn=[
{address="0x000107bc",func-name="main",offset="0",
inst="save %sp, -112, %sp"}]},
src_and_asm_line={line="32",
file="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb/ \
testsuite/gdb.mi/basics.c",line_asm_insn=[
{address="0x000107c0",func-name="main",offset="4",
inst="mov 2, %o0"},
{address="0x000107c4",func-name="main",offset="8",
inst="sethi %hi(0x11800), %o2"}]}]
(gdb)
The `-data-evaluate-expression' Command
---------------------------------------
Synopsis
........
-data-evaluate-expression EXPR
Evaluate EXPR as an expression. The expression could contain an
inferior function call. The function call will execute synchronously.
If the expression contains spaces, it must be enclosed in double quotes.
GDB Command
...........
The corresponding GDB commands are `print', `output', and `call'. In
`gdbtk' only, there's a corresponding `gdb_eval' command.
Example
.......
In the following example, the numbers that precede the commands are the
"tokens" described in *Note GDB/MI Command Syntax: GDB/MI Command
Syntax. Notice how GDB/MI returns the same tokens in its output.
211-data-evaluate-expression A
211^done,value="1"
(gdb)
311-data-evaluate-expression &A
311^done,value="0xefffeb7c"
(gdb)
411-data-evaluate-expression A+3
411^done,value="4"
(gdb)
511-data-evaluate-expression "A + 3"
511^done,value="4"
(gdb)
The `-data-list-changed-registers' Command
------------------------------------------
Synopsis
........
-data-list-changed-registers
Display a list of the registers that have changed.
GDB Command
...........
GDB doesn't have a direct analog for this command; `gdbtk' has the
corresponding command `gdb_changed_register_list'.
Example
.......
On a PPC MBX board:
(gdb)
-exec-continue
^running
(gdb)
*stopped,reason="breakpoint-hit",bkptno="1",frame={func="main",
args=[],file="try.c",line="5"}
(gdb)
-data-list-changed-registers
^done,changed-registers=["0","1","2","4","5","6","7","8","9",
"10","11","13","14","15","16","17","18","19","20","21","22","23",
"24","25","26","27","28","30","31","64","65","66","67","69"]
(gdb)
The `-data-list-register-names' Command
---------------------------------------
Synopsis
........
-data-list-register-names [ ( REGNO )+ ]
Show a list of register names for the current target. If no
arguments are given, it shows a list of the names of all the registers.
If integer numbers are given as arguments, it will print a list of the
names of the registers corresponding to the arguments. To ensure
consistency between a register name and its number, the output list may
include empty register names.
GDB Command
...........
GDB does not have a command which corresponds to
`-data-list-register-names'. In `gdbtk' there is a corresponding
command `gdb_regnames'.
Example
.......
For the PPC MBX board:
(gdb)
-data-list-register-names
^done,register-names=["r0","r1","r2","r3","r4","r5","r6","r7",
"r8","r9","r10","r11","r12","r13","r14","r15","r16","r17","r18",
"r19","r20","r21","r22","r23","r24","r25","r26","r27","r28","r29",
"r30","r31","f0","f1","f2","f3","f4","f5","f6","f7","f8","f9",
"f10","f11","f12","f13","f14","f15","f16","f17","f18","f19","f20",
"f21","f22","f23","f24","f25","f26","f27","f28","f29","f30","f31",
"", "pc","ps","cr","lr","ctr","xer"]
(gdb)
-data-list-register-names 1 2 3
^done,register-names=["r1","r2","r3"]
(gdb)
The `-data-list-register-values' Command
----------------------------------------
Synopsis
........
-data-list-register-values FMT [ ( REGNO )*]
Display the registers' contents. FMT is the format according to
which the registers' contents are to be returned, followed by an
optional list of numbers specifying the registers to display. A
missing list of numbers indicates that the contents of all the
registers must be returned.
Allowed formats for FMT are:
`x'
Hexadecimal
`o'
Octal
`t'
Binary
`d'
Decimal
`r'
Raw
`N'
Natural
GDB Command
...........
The corresponding GDB commands are `info reg', `info all-reg', and (in
`gdbtk') `gdb_fetch_registers'.
Example
.......
For a PPC MBX board (note: line breaks are for readability only, they
don't appear in the actual output):
(gdb)
-data-list-register-values r 64 65
^done,register-values=[{number="64",value="0xfe00a300"},
{number="65",value="0x00029002"}]
(gdb)
-data-list-register-values x
^done,register-values=[{number="0",value="0xfe0043c8"},
{number="1",value="0x3fff88"},{number="2",value="0xfffffffe"},
{number="3",value="0x0"},{number="4",value="0xa"},
{number="5",value="0x3fff68"},{number="6",value="0x3fff58"},
{number="7",value="0xfe011e98"},{number="8",value="0x2"},
{number="9",value="0xfa202820"},{number="10",value="0xfa202808"},
{number="11",value="0x1"},{number="12",value="0x0"},
{number="13",value="0x4544"},{number="14",value="0xffdfffff"},
{number="15",value="0xffffffff"},{number="16",value="0xfffffeff"},
{number="17",value="0xefffffed"},{number="18",value="0xfffffffe"},
{number="19",value="0xffffffff"},{number="20",value="0xffffffff"},
{number="21",value="0xffffffff"},{number="22",value="0xfffffff7"},
{number="23",value="0xffffffff"},{number="24",value="0xffffffff"},
{number="25",value="0xffffffff"},{number="26",value="0xfffffffb"},
{number="27",value="0xffffffff"},{number="28",value="0xf7bfffff"},
{number="29",value="0x0"},{number="30",value="0xfe010000"},
{number="31",value="0x0"},{number="32",value="0x0"},
{number="33",value="0x0"},{number="34",value="0x0"},
{number="35",value="0x0"},{number="36",value="0x0"},
{number="37",value="0x0"},{number="38",value="0x0"},
{number="39",value="0x0"},{number="40",value="0x0"},
{number="41",value="0x0"},{number="42",value="0x0"},
{number="43",value="0x0"},{number="44",value="0x0"},
{number="45",value="0x0"},{number="46",value="0x0"},
{number="47",value="0x0"},{number="48",value="0x0"},
{number="49",value="0x0"},{number="50",value="0x0"},
{number="51",value="0x0"},{number="52",value="0x0"},
{number="53",value="0x0"},{number="54",value="0x0"},
{number="55",value="0x0"},{number="56",value="0x0"},
{number="57",value="0x0"},{number="58",value="0x0"},
{number="59",value="0x0"},{number="60",value="0x0"},
{number="61",value="0x0"},{number="62",value="0x0"},
{number="63",value="0x0"},{number="64",value="0xfe00a300"},
{number="65",value="0x29002"},{number="66",value="0x202f04b5"},
{number="67",value="0xfe0043b0"},{number="68",value="0xfe00b3e4"},
{number="69",value="0x20002b03"}]
(gdb)
The `-data-read-memory' Command
-------------------------------
Synopsis
........
-data-read-memory [ -o BYTE-OFFSET ]
ADDRESS WORD-FORMAT WORD-SIZE
NR-ROWS NR-COLS [ ASCHAR ]
where:
`ADDRESS'
An expression specifying the address of the first memory word to be
read. Complex expressions containing embedded white space should
be quoted using the C convention.
`WORD-FORMAT'
The format to be used to print the memory words. The notation is
the same as for GDB's `print' command (*note Output formats:
Output Formats.).
`WORD-SIZE'
The size of each memory word in bytes.
`NR-ROWS'
The number of rows in the output table.
`NR-COLS'
The number of columns in the output table.
`ASCHAR'
If present, indicates that each row should include an ASCII dump.
The value of ASCHAR is used as a padding character when a byte is
not a member of the printable ASCII character set (printable ASCII
characters are those whose code is between 32 and 126,
inclusively).
`BYTE-OFFSET'
An offset to add to the ADDRESS before fetching memory.
This command displays memory contents as a table of NR-ROWS by
NR-COLS words, each word being WORD-SIZE bytes. In total, `NR-ROWS *
NR-COLS * WORD-SIZE' bytes are read (returned as `total-bytes').
Should less than the requested number of bytes be returned by the
target, the missing words are identified using `N/A'. The number of
bytes read from the target is returned in `nr-bytes' and the starting
address used to read memory in `addr'.
The address of the next/previous row or page is available in
`next-row' and `prev-row', `next-page' and `prev-page'.
GDB Command
...........
The corresponding GDB command is `x'. `gdbtk' has `gdb_get_mem' memory
read command.
Example
.......
Read six bytes of memory starting at `bytes+6' but then offset by `-6'
bytes. Format as three rows of two columns. One byte per word.
Display each word in hex.
(gdb)
9-data-read-memory -o -6 -- bytes+6 x 1 3 2
9^done,addr="0x00001390",nr-bytes="6",total-bytes="6",
next-row="0x00001396",prev-row="0x0000138e",next-page="0x00001396",
prev-page="0x0000138a",memory=[
{addr="0x00001390",data=["0x00","0x01"]},
{addr="0x00001392",data=["0x02","0x03"]},
{addr="0x00001394",data=["0x04","0x05"]}]
(gdb)
Read two bytes of memory starting at address `shorts + 64' and
display as a single word formatted in decimal.
(gdb)
5-data-read-memory shorts+64 d 2 1 1
5^done,addr="0x00001510",nr-bytes="2",total-bytes="2",
next-row="0x00001512",prev-row="0x0000150e",
next-page="0x00001512",prev-page="0x0000150e",memory=[
{addr="0x00001510",data=["128"]}]
(gdb)
Read thirty two bytes of memory starting at `bytes+16' and format as
eight rows of four columns. Include a string encoding with `x' used as
the non-printable character.
(gdb)
4-data-read-memory bytes+16 x 1 8 4 x
4^done,addr="0x000013a0",nr-bytes="32",total-bytes="32",
next-row="0x000013c0",prev-row="0x0000139c",
next-page="0x000013c0",prev-page="0x00001380",memory=[
{addr="0x000013a0",data=["0x10","0x11","0x12","0x13"],ascii="xxxx"},
{addr="0x000013a4",data=["0x14","0x15","0x16","0x17"],ascii="xxxx"},
{addr="0x000013a8",data=["0x18","0x19","0x1a","0x1b"],ascii="xxxx"},
{addr="0x000013ac",data=["0x1c","0x1d","0x1e","0x1f"],ascii="xxxx"},
{addr="0x000013b0",data=["0x20","0x21","0x22","0x23"],ascii=" !\"#"},
{addr="0x000013b4",data=["0x24","0x25","0x26","0x27"],ascii="$%&'"},
{addr="0x000013b8",data=["0x28","0x29","0x2a","0x2b"],ascii="()*+"},
{addr="0x000013bc",data=["0x2c","0x2d","0x2e","0x2f"],ascii=",-./"}]
(gdb)
The `-display-delete' Command
-----------------------------
Synopsis
........
-display-delete NUMBER
Delete the display NUMBER.
GDB Command
...........
The corresponding GDB command is `delete display'.
Example
.......
N.A.
The `-display-disable' Command
------------------------------
Synopsis
........
-display-disable NUMBER
Disable display NUMBER.
GDB Command
...........
The corresponding GDB command is `disable display'.
Example
.......
N.A.
The `-display-enable' Command
-----------------------------
Synopsis
........
-display-enable NUMBER
Enable display NUMBER.
GDB Command
...........
The corresponding GDB command is `enable display'.
Example
.......
N.A.
The `-display-insert' Command
-----------------------------
Synopsis
........
-display-insert EXPRESSION
Display EXPRESSION every time the program stops.
GDB Command
...........
The corresponding GDB command is `display'.
Example
.......
N.A.
The `-display-list' Command
---------------------------
Synopsis
........
-display-list
List the displays. Do not show the current values.
GDB Command
...........
The corresponding GDB command is `info display'.
Example
.......
N.A.
The `-environment-cd' Command
-----------------------------
Synopsis
........
-environment-cd PATHDIR
Set GDB's working directory.
GDB Command
...........
The corresponding GDB command is `cd'.
Example
.......
(gdb)
-environment-cd /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
^done
(gdb)
The `-environment-directory' Command
------------------------------------
Synopsis
........
-environment-directory [ -r ] [ PATHDIR ]+
Add directories PATHDIR to beginning of search path for source files.
If the `-r' option is used, the search path is reset to the default
search path. If directories PATHDIR are supplied in addition to the
`-r' option, the search path is first reset and then addition occurs as
normal. Multiple directories may be specified, separated by blanks.
Specifying multiple directories in a single command results in the
directories added to the beginning of the search path in the same order
they were presented in the command. If blanks are needed as part of a
directory name, double-quotes should be used around the name. In the
command output, the path will show up separated by the system
directory-separator character. The directory-seperator character must
not be used in any directory name. If no directories are specified,
the current search path is displayed.
GDB Command
...........
The corresponding GDB command is `dir'.
Example
.......
(gdb)
-environment-directory /kwikemart/marge/ezannoni/flathead-dev/devo/gdb
^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
(gdb)
-environment-directory ""
^done,source-path="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb:$cdir:$cwd"
(gdb)
-environment-directory -r /home/jjohnstn/src/gdb /usr/src
^done,source-path="/home/jjohnstn/src/gdb:/usr/src:$cdir:$cwd"
(gdb)
-environment-directory -r
^done,source-path="$cdir:$cwd"
(gdb)
The `-environment-path' Command
-------------------------------
Synopsis
........
-environment-path [ -r ] [ PATHDIR ]+
Add directories PATHDIR to beginning of search path for object files.
If the `-r' option is used, the search path is reset to the original
search path that existed at gdb start-up. If directories PATHDIR are
supplied in addition to the `-r' option, the search path is first reset
and then addition occurs as normal. Multiple directories may be
specified, separated by blanks. Specifying multiple directories in a
single command results in the directories added to the beginning of the
search path in the same order they were presented in the command. If
blanks are needed as part of a directory name, double-quotes should be
used around the name. In the command output, the path will show up
separated by the system directory-separator character. The
directory-seperator character must not be used in any directory name.
If no directories are specified, the current path is displayed.
GDB Command
...........
The corresponding GDB command is `path'.
Example
.......
(gdb)
-environment-path
^done,path="/usr/bin"
(gdb)
-environment-path /kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb /bin
^done,path="/kwikemart/marge/ezannoni/flathead-dev/ppc-eabi/gdb:/bin:/usr/bin"
(gdb)
-environment-path -r /usr/local/bin
^done,path="/usr/local/bin:/usr/bin"
(gdb)
The `-environment-pwd' Command
------------------------------
Synopsis
........
-environment-pwd
Show the current working directory.
GDB command
...........
The corresponding GDB command is `pwd'.
Example
.......
(gdb)
-environment-pwd
^done,cwd="/kwikemart/marge/ezannoni/flathead-dev/devo/gdb"
(gdb)
File: gdb.info, Node: GDB/MI Program Control, Next: GDB/MI Miscellaneous Commands, Prev: GDB/MI Data Manipulation, Up: GDB/MI
GDB/MI Program control
======================
Program termination
...................
As a result of execution, the inferior program can run to completion, if
it doesn't encounter any breakpoints. In this case the output will
include an exit code, if the program has exited exceptionally.
Examples
........
Program exited normally:
(gdb)
-exec-run
^running
(gdb)
x = 55
*stopped,reason="exited-normally"
(gdb)
Program exited exceptionally:
(gdb)
-exec-run
^running
(gdb)
x = 55
*stopped,reason="exited",exit-code="01"
(gdb)
Another way the program can terminate is if it receives a signal
such as `SIGINT'. In this case, GDB/MI displays this:
(gdb)
*stopped,reason="exited-signalled",signal-name="SIGINT",
signal-meaning="Interrupt"
The `-exec-abort' Command
-------------------------
Synopsis
........
-exec-abort
Kill the inferior running program.
GDB Command
...........
The corresponding GDB command is `kill'.
Example
.......
N.A.
The `-exec-arguments' Command
-----------------------------
Synopsis
........
-exec-arguments ARGS
Set the inferior program arguments, to be used in the next
`-exec-run'.
GDB Command
...........
The corresponding GDB command is `set args'.
Example
.......
Don't have one around.
The `-exec-continue' Command
----------------------------
Synopsis
........
-exec-continue
Asynchronous command. Resumes the execution of the inferior program
until a breakpoint is encountered, or until the inferior exits.
GDB Command
...........
The corresponding GDB corresponding is `continue'.
Example
.......
-exec-continue
^running
(gdb)
@Hello world
*stopped,reason="breakpoint-hit",bkptno="2",frame={func="foo",args=[],
file="hello.c",line="13"}
(gdb)
The `-exec-finish' Command
--------------------------
Synopsis
........
-exec-finish
Asynchronous command. Resumes the execution of the inferior program
until the current function is exited. Displays the results returned by
the function.
GDB Command
...........
The corresponding GDB command is `finish'.
Example
.......
Function returning `void'.
-exec-finish
^running
(gdb)
@hello from foo
*stopped,reason="function-finished",frame={func="main",args=[],
file="hello.c",line="7"}
(gdb)
Function returning other than `void'. The name of the internal GDB
variable storing the result is printed, together with the value itself.
-exec-finish
^running
(gdb)
*stopped,reason="function-finished",frame={addr="0x000107b0",func="foo",
args=[{name="a",value="1"],{name="b",value="9"}},
file="recursive2.c",line="14"},
gdb-result-var="$1",return-value="0"
(gdb)
The `-exec-interrupt' Command
-----------------------------
Synopsis
........
-exec-interrupt
Asynchronous command. Interrupts the background execution of the
target. Note how the token associated with the stop message is the one
for the execution command that has been interrupted. The token for the
interrupt itself only appears in the `^done' output. If the user is
trying to interrupt a non-running program, an error message will be
printed.
GDB Command
...........
The corresponding GDB command is `interrupt'.
Example
.......
(gdb)
111-exec-continue
111^running
(gdb)
222-exec-interrupt
222^done
(gdb)
111*stopped,signal-name="SIGINT",signal-meaning="Interrupt",
frame={addr="0x00010140",func="foo",args=[],file="try.c",line="13"}
(gdb)
(gdb)
-exec-interrupt
^error,msg="mi_cmd_exec_interrupt: Inferior not executing."
(gdb)
The `-exec-next' Command
------------------------
Synopsis
........
-exec-next
Asynchronous command. Resumes execution of the inferior program,
stopping when the beginning of the next source line is reached.
GDB Command
...........
The corresponding GDB command is `next'.
Example
.......
-exec-next
^running
(gdb)
*stopped,reason="end-stepping-range",line="8",file="hello.c"
(gdb)
The `-exec-next-instruction' Command
------------------------------------
Synopsis
........
-exec-next-instruction
Asynchronous command. Executes one machine instruction. If the
instruction is a function call continues until the function returns. If
the program stops at an instruction in the middle of a source line, the
address will be printed as well.
GDB Command
...........
The corresponding GDB command is `nexti'.
Example
.......
(gdb)
-exec-next-instruction
^running
(gdb)
*stopped,reason="end-stepping-range",
addr="0x000100d4",line="5",file="hello.c"
(gdb)
The `-exec-return' Command
--------------------------
Synopsis
........
-exec-return
Makes current function return immediately. Doesn't execute the
inferior. Displays the new current frame.
GDB Command
...........
The corresponding GDB command is `return'.
Example
.......
(gdb)
200-break-insert callee4
200^done,bkpt={number="1",addr="0x00010734",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"}
(gdb)
000-exec-run
000^running
(gdb)
000*stopped,reason="breakpoint-hit",bkptno="1",
frame={func="callee4",args=[],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"}
(gdb)
205-break-delete
205^done
(gdb)
111-exec-return
111^done,frame={level="0",func="callee3",
args=[{name="strarg",
value="0x11940 \"A string argument.\""}],
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="18"}
(gdb)
The `-exec-run' Command
-----------------------
Synopsis
........
-exec-run
Asynchronous command. Starts execution of the inferior from the
beginning. The inferior executes until either a breakpoint is
encountered or the program exits.
GDB Command
...........
The corresponding GDB command is `run'.
Example
.......
(gdb)
-break-insert main
^done,bkpt={number="1",addr="0x0001072c",file="recursive2.c",line="4"}
(gdb)
-exec-run
^running
(gdb)
*stopped,reason="breakpoint-hit",bkptno="1",
frame={func="main",args=[],file="recursive2.c",line="4"}
(gdb)
The `-exec-show-arguments' Command
----------------------------------
Synopsis
........
-exec-show-arguments
Print the arguments of the program.
GDB Command
...........
The corresponding GDB command is `show args'.
Example
.......
N.A.
The `-exec-step' Command
------------------------
Synopsis
........
-exec-step
Asynchronous command. Resumes execution of the inferior program,
stopping when the beginning of the next source line is reached, if the
next source line is not a function call. If it is, stop at the first
instruction of the called function.
GDB Command
...........
The corresponding GDB command is `step'.
Example
.......
Stepping into a function:
-exec-step
^running
(gdb)
*stopped,reason="end-stepping-range",
frame={func="foo",args=[{name="a",value="10"},
{name="b",value="0"}],file="recursive2.c",line="11"}
(gdb)
Regular stepping:
-exec-step
^running
(gdb)
*stopped,reason="end-stepping-range",line="14",file="recursive2.c"
(gdb)
The `-exec-step-instruction' Command
------------------------------------
Synopsis
........
-exec-step-instruction
Asynchronous command. Resumes the inferior which executes one
machine instruction. The output, once GDB has stopped, will vary
depending on whether we have stopped in the middle of a source line or
not. In the former case, the address at which the program stopped will
be printed as well.
GDB Command
...........
The corresponding GDB command is `stepi'.
Example
.......
(gdb)
-exec-step-instruction
^running
(gdb)
*stopped,reason="end-stepping-range",
frame={func="foo",args=[],file="try.c",line="10"}
(gdb)
-exec-step-instruction
^running
(gdb)
*stopped,reason="end-stepping-range",
frame={addr="0x000100f4",func="foo",args=[],file="try.c",line="10"}
(gdb)
The `-exec-until' Command
-------------------------
Synopsis
........
-exec-until [ LOCATION ]
Asynchronous command. Executes the inferior until the LOCATION
specified in the argument is reached. If there is no argument, the
inferior executes until a source line greater than the current one is
reached. The reason for stopping in this case will be
`location-reached'.
GDB Command
...........
The corresponding GDB command is `until'.
Example
.......
(gdb)
-exec-until recursive2.c:6
^running
(gdb)
x = 55
*stopped,reason="location-reached",frame={func="main",args=[],
file="recursive2.c",line="6"}
(gdb)
The `-file-exec-and-symbols' Command
------------------------------------
Synopsis
........
-file-exec-and-symbols FILE
Specify the executable file to be debugged. This file is the one
from which the symbol table is also read. If no file is specified, the
command clears the executable and symbol information. If breakpoints
are set when using this command with no arguments, GDB will produce
error messages. Otherwise, no output is produced, except a completion
notification.
GDB Command
...........
The corresponding GDB command is `file'.
Example
.......
(gdb)
-file-exec-and-symbols /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)
The `-file-exec-file' Command
-----------------------------
Synopsis
........
-file-exec-file FILE
Specify the executable file to be debugged. Unlike
`-file-exec-and-symbols', the symbol table is _not_ read from this
file. If used without argument, GDB clears the information about the
executable file. No output is produced, except a completion
notification.
GDB Command
...........
The corresponding GDB command is `exec-file'.
Example
.......
(gdb)
-file-exec-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)
The `-file-list-exec-sections' Command
--------------------------------------
Synopsis
........
-file-list-exec-sections
List the sections of the current executable file.
GDB Command
...........
The GDB command `info file' shows, among the rest, the same information
as this command. `gdbtk' has a corresponding command `gdb_load_info'.
Example
.......
N.A.
The `-file-list-exec-source-file' Command
-----------------------------------------
Synopsis
........
-file-list-exec-source-file
List the line number, the current source file, and the absolute path
to the current source file for the current executable.
GDB Command
...........
There's no GDB command which directly corresponds to this one.
Example
.......
(gdb)
123-file-list-exec-source-file
123^done,line="1",file="foo.c",fullname="/home/bar/foo.c"
(gdb)
The `-file-list-exec-source-files' Command
------------------------------------------
Synopsis
........
-file-list-exec-source-files
List the source files for the current executable.
GDB Command
...........
There's no GDB command which directly corresponds to this one. `gdbtk'
has an analogous command `gdb_listfiles'.
Example
.......
N.A.
The `-file-list-shared-libraries' Command
-----------------------------------------
Synopsis
........
-file-list-shared-libraries
List the shared libraries in the program.
GDB Command
...........
The corresponding GDB command is `info shared'.
Example
.......
N.A.
The `-file-list-symbol-files' Command
-------------------------------------
Synopsis
........
-file-list-symbol-files
List symbol files.
GDB Command
...........
The corresponding GDB command is `info file' (part of it).
Example
.......
N.A.
The `-file-symbol-file' Command
-------------------------------
Synopsis
........
-file-symbol-file FILE
Read symbol table info from the specified FILE argument. When used
without arguments, clears GDB's symbol table info. No output is
produced, except for a completion notification.
GDB Command
...........
The corresponding GDB command is `symbol-file'.
Example
.......
(gdb)
-file-symbol-file /kwikemart/marge/ezannoni/TRUNK/mbx/hello.mbx
^done
(gdb)
File: gdb.info, Node: GDB/MI Miscellaneous Commands, Next: GDB/MI Stack Manipulation, Prev: GDB/MI Program Control, Up: GDB/MI
Miscellaneous GDB commands in GDB/MI
====================================
The `-gdb-exit' Command
-----------------------
Synopsis
........
-gdb-exit
Exit GDB immediately.
GDB Command
...........
Approximately corresponds to `quit'.
Example
.......
(gdb)
-gdb-exit
The `-gdb-set' Command
----------------------
Synopsis
........
-gdb-set
Set an internal GDB variable.
GDB Command
...........
The corresponding GDB command is `set'.
Example
.......
(gdb)
-gdb-set $foo=3
^done
(gdb)
The `-gdb-show' Command
-----------------------
Synopsis
........
-gdb-show
Show the current value of a GDB variable.
GDB command
...........
The corresponding GDB command is `show'.
Example
.......
(gdb)
-gdb-show annotate
^done,value="0"
(gdb)
The `-gdb-version' Command
--------------------------
Synopsis
........
-gdb-version
Show version information for GDB. Used mostly in testing.
GDB Command
...........
There's no equivalent GDB command. GDB by default shows this
information when you start an interactive session.
Example
.......
(gdb)
-gdb-version
~GNU gdb 5.2.1
~Copyright 2000 Free Software Foundation, Inc.
~GDB is free software, covered by the GNU General Public License, and
~you are welcome to change it and/or distribute copies of it under
~ certain conditions.
~Type "show copying" to see the conditions.
~There is absolutely no warranty for GDB. Type "show warranty" for
~ details.
~This GDB was configured as
"--host=sparc-sun-solaris2.5.1 --target=ppc-eabi".
^done
(gdb)
The `-interpreter-exec' Command
-------------------------------
Synopsis
--------
-interpreter-exec INTERPRETER COMMAND
Execute the specified COMMAND in the given INTERPRETER.
GDB Command
-----------
The corresponding GDB command is `interpreter-exec'.
Example
-------
(gdb)
-interpreter-exec console "break main"
&"During symbol reading, couldn't parse type; debugger out of date?.\n"
&"During symbol reading, bad structure-type format.\n"
~"Breakpoint 1 at 0x8074fc6: file ../../src/gdb/main.c, line 743.\n"
^done
(gdb)
File: gdb.info, Node: GDB/MI Stack Manipulation, Next: GDB/MI Symbol Query, Prev: GDB/MI Miscellaneous Commands, Up: GDB/MI
GDB/MI Stack Manipulation Commands
==================================
The `-stack-info-frame' Command
-------------------------------
Synopsis
........
-stack-info-frame
Get info on the current frame.
GDB Command
...........
The corresponding GDB command is `info frame' or `frame' (without
arguments).
Example
.......
N.A.
The `-stack-info-depth' Command
-------------------------------
Synopsis
........
-stack-info-depth [ MAX-DEPTH ]
Return the depth of the stack. If the integer argument MAX-DEPTH is
specified, do not count beyond MAX-DEPTH frames.
GDB Command
...........
There's no equivalent GDB command.
Example
.......
For a stack with frame levels 0 through 11:
(gdb)
-stack-info-depth
^done,depth="12"
(gdb)
-stack-info-depth 4
^done,depth="4"
(gdb)
-stack-info-depth 12
^done,depth="12"
(gdb)
-stack-info-depth 11
^done,depth="11"
(gdb)
-stack-info-depth 13
^done,depth="12"
(gdb)
The `-stack-list-arguments' Command
-----------------------------------
Synopsis
........
-stack-list-arguments SHOW-VALUES
[ LOW-FRAME HIGH-FRAME ]
Display a list of the arguments for the frames between LOW-FRAME and
HIGH-FRAME (inclusive). If LOW-FRAME and HIGH-FRAME are not provided,
list the arguments for the whole call stack.
The SHOW-VALUES argument must have a value of 0 or 1. A value of 0
means that only the names of the arguments are listed, a value of 1
means that both names and values of the arguments are printed.
GDB Command
...........
GDB does not have an equivalent command. `gdbtk' has a `gdb_get_args'
command which partially overlaps with the functionality of
`-stack-list-arguments'.
Example
.......
(gdb)
-stack-list-frames
^done,
stack=[
frame={level="0",addr="0x00010734",func="callee4",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="8"},
frame={level="1",addr="0x0001076c",func="callee3",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="17"},
frame={level="2",addr="0x0001078c",func="callee2",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="22"},
frame={level="3",addr="0x000107b4",func="callee1",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="27"},
frame={level="4",addr="0x000107e0",func="main",
file="../../../devo/gdb/testsuite/gdb.mi/basics.c",line="32"}]
(gdb)
-stack-list-arguments 0
^done,
stack-args=[
frame={level="0",args=[]},
frame={level="1",args=[name="strarg"]},
frame={level="2",args=[name="intarg",name="strarg"]},
frame={level="3",args=[name="intarg",name="strarg",name="fltarg"]},
frame={level="4",args=[]}]
(gdb)
-stack-list-arguments 1
^done,
stack-args=[
frame={level="0",args=[]},
frame={level="1",
args=[{name="strarg",value="0x11940 \"A string argument.\""}]},
frame={level="2",args=[
{name="intarg",value="2"},
{name="strarg",value="0x11940 \"A string argument.\""}]},
{frame={level="3",args=[
{name="intarg",value="2"},
{name="strarg",value="0x11940 \"A string argument.\""},
{name="fltarg",value="3.5"}]},
frame={level="4",args=[]}]
(gdb)
-stack-list-arguments 0 2 2
^done,stack-args=[frame={level="2",args=[name="intarg",name="strarg"]}]
(gdb)
-stack-list-arguments 1 2 2
^done,stack-args=[frame={level="2",
args=[{name="intarg",value="2"},
{name="strarg",value="0x11940 \"A string argument.\""}]}]
(gdb)
The `-stack-list-frames' Command
--------------------------------
Synopsis
........
-stack-list-frames [ LOW-FRAME HIGH-FRAME ]
List the frames currently on the stack. For each frame it displays
the following info:
`LEVEL'
The frame number, 0 being the topmost frame, i.e. the innermost
function.
`ADDR'
The `$pc' value for that frame.
`FUNC'
Function name.
`FILE'
File name of the source file where the function lives.
`LINE'
Line number corresponding to the `$pc'.
If invoked without arguments, this command prints a backtrace for the
whole stack. If given two integer arguments, it shows the frames whose
levels are between the two arguments (inclusive). If the two arguments
are equal, it shows the single frame at the corresponding level.
GDB Command
...........
The corresponding GDB commands are `backtrace' and `where'.
Example
.......
Full stack backtrace:
(gdb)
-stack-list-frames
^done,stack=
[frame={level="0",addr="0x0001076c",func="foo",
file="recursive2.c",line="11"},
frame={level="1",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="2",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="3",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="4",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="5",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="6",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="7",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="8",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="9",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="10",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="11",addr="0x00010738",func="main",
file="recursive2.c",line="4"}]
(gdb)
Show frames between LOW_FRAME and HIGH_FRAME:
(gdb)
-stack-list-frames 3 5
^done,stack=
[frame={level="3",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="4",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"},
frame={level="5",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"}]
(gdb)
Show a single frame:
(gdb)
-stack-list-frames 3 3
^done,stack=
[frame={level="3",addr="0x000107a4",func="foo",
file="recursive2.c",line="14"}]
(gdb)
The `-stack-list-locals' Command
--------------------------------
Synopsis
........
-stack-list-locals PRINT-VALUES
Display the local variable names for the current frame. With an
argument of 0 or `--no-values', prints only the names of the variables.
With argument of 1 or `--all-values', prints also their values. With
argument of 2 or `--simple-values', prints the name, type and value for
simple data types and the name and type for arrays, structures and
unions. In this last case, the idea is that the user can see the value
of simple data types immediately and he can create variable objects for
other data types if he wishes to explore their values in more detail.
GDB Command
...........
`info locals' in GDB, `gdb_get_locals' in `gdbtk'.
Example
.......
(gdb)
-stack-list-locals 0
^done,locals=[name="A",name="B",name="C"]
(gdb)
-stack-list-locals --all-values
^done,locals=[{name="A",value="1"},{name="B",value="2"},
{name="C",value="{1, 2, 3}"}]
-stack-list-locals --simple-values
^done,locals=[{name="A",type="int",value="1"},
{name="B",type="int",value="2"},{name="C",type="int [3]"}]
(gdb)
The `-stack-select-frame' Command
---------------------------------
Synopsis
........
-stack-select-frame FRAMENUM
Change the current frame. Select a different frame FRAMENUM on the
stack.
GDB Command
...........
The corresponding GDB commands are `frame', `up', `down',
`select-frame', `up-silent', and `down-silent'.
Example
.......
(gdb)
-stack-select-frame 2
^done
(gdb)
File: gdb.info, Node: GDB/MI Symbol Query, Next: GDB/MI Target Manipulation, Prev: GDB/MI Stack Manipulation, Up: GDB/MI
GDB/MI Symbol Query Commands
============================
The `-symbol-info-address' Command
----------------------------------
Synopsis
........
-symbol-info-address SYMBOL
Describe where SYMBOL is stored.
GDB Command
...........
The corresponding GDB command is `info address'.
Example
.......
N.A.
The `-symbol-info-file' Command
-------------------------------
Synopsis
........
-symbol-info-file
Show the file for the symbol.
GDB Command
...........
There's no equivalent GDB command. `gdbtk' has `gdb_find_file'.
Example
.......
N.A.
The `-symbol-info-function' Command
-----------------------------------
Synopsis
........
-symbol-info-function
Show which function the symbol lives in.
GDB Command
...........
`gdb_get_function' in `gdbtk'.
Example
.......
N.A.
The `-symbol-info-line' Command
-------------------------------
Synopsis
........
-symbol-info-line
Show the core addresses of the code for a source line.
GDB Command
...........
The corresponding GDB command is `info line'. `gdbtk' has the
`gdb_get_line' and `gdb_get_file' commands.
Example
.......
N.A.
The `-symbol-info-symbol' Command
---------------------------------
Synopsis
........
-symbol-info-symbol ADDR
Describe what symbol is at location ADDR.
GDB Command
...........
The corresponding GDB command is `info symbol'.
Example
.......
N.A.
The `-symbol-list-functions' Command
------------------------------------
Synopsis
........
-symbol-list-functions
List the functions in the executable.
GDB Command
...........
`info functions' in GDB, `gdb_listfunc' and `gdb_search' in `gdbtk'.
Example
.......
N.A.
The `-symbol-list-lines' Command
--------------------------------
Synopsis
........
-symbol-list-lines FILENAME
Print the list of lines that contain code and their associated
program addresses for the given source filename. The entries are
sorted in ascending PC order.
GDB Command
...........
There is no corresponding GDB command.
Example
.......
(gdb)
-symbol-list-lines basics.c
^done,lines=[{pc="0x08048554",line="7"},{pc="0x0804855a",line="8"}]
(gdb)
The `-symbol-list-types' Command
--------------------------------
Synopsis
........
-symbol-list-types
List all the type names.
GDB Command
...........
The corresponding commands are `info types' in GDB, `gdb_search' in
`gdbtk'.
Example
.......
N.A.
The `-symbol-list-variables' Command
------------------------------------
Synopsis
........
-symbol-list-variables
List all the global and static variable names.
GDB Command
...........
`info variables' in GDB, `gdb_search' in `gdbtk'.
Example
.......
N.A.
The `-symbol-locate' Command
----------------------------
Synopsis
........
-symbol-locate
GDB Command
...........
`gdb_loc' in `gdbtk'.
Example
.......
N.A.
The `-symbol-type' Command
--------------------------
Synopsis
........
-symbol-type VARIABLE
Show type of VARIABLE.
GDB Command
...........
The corresponding GDB command is `ptype', `gdbtk' has
`gdb_obj_variable'.
Example
.......
N.A.
File: gdb.info, Node: GDB/MI Target Manipulation, Next: GDB/MI Thread Commands, Prev: GDB/MI Symbol Query, Up: GDB/MI
GDB/MI Target Manipulation Commands
===================================
The `-target-attach' Command
----------------------------
Synopsis
........
-target-attach PID | FILE
Attach to a process PID or a file FILE outside of GDB.
GDB command
...........
The corresponding GDB command is `attach'.
Example
.......
N.A.
The `-target-compare-sections' Command
--------------------------------------
Synopsis
........
-target-compare-sections [ SECTION ]
Compare data of section SECTION on target to the exec file. Without
the argument, all sections are compared.
GDB Command
...........
The GDB equivalent is `compare-sections'.
Example
.......
N.A.
The `-target-detach' Command
----------------------------
Synopsis
........
-target-detach
Disconnect from the remote target. There's no output.
GDB command
...........
The corresponding GDB command is `detach'.
Example
.......
(gdb)
-target-detach
^done
(gdb)
The `-target-disconnect' Command
--------------------------------
Synopsis
........
-target-disconnect
Disconnect from the remote target. There's no output.
GDB command
...........
The corresponding GDB command is `disconnect'.
Example
.......
(gdb)
-target-disconnect
^done
(gdb)
The `-target-download' Command
------------------------------
Synopsis
........
-target-download
Loads the executable onto the remote target. It prints out an
update message every half second, which includes the fields:
`section'
The name of the section.
`section-sent'
The size of what has been sent so far for that section.
`section-size'
The size of the section.
`total-sent'
The total size of what was sent so far (the current and the
previous sections).
`total-size'
The size of the overall executable to download.
Each message is sent as status record (*note GDB/MI Output Syntax:
GDB/MI Output Syntax.).
In addition, it prints the name and size of the sections, as they are
downloaded. These messages include the following fields:
`section'
The name of the section.
`section-size'
The size of the section.
`total-size'
The size of the overall executable to download.
At the end, a summary is printed.
GDB Command
...........
The corresponding GDB command is `load'.
Example
.......
Note: each status message appears on a single line. Here the messages
have been broken down so that they can fit onto a page.
(gdb)
-target-download
+download,{section=".text",section-size="6668",total-size="9880"}
+download,{section=".text",section-sent="512",section-size="6668",
total-sent="512",total-size="9880"}
+download,{section=".text",section-sent="1024",section-size="6668",
total-sent="1024",total-size="9880"}
+download,{section=".text",section-sent="1536",section-size="6668",
total-sent="1536",total-size="9880"}
+download,{section=".text",section-sent="2048",section-size="6668",
total-sent="2048",total-size="9880"}
+download,{section=".text",section-sent="2560",section-size="6668",
total-sent="2560",total-size="9880"}
+download,{section=".text",section-sent="3072",section-size="6668",
total-sent="3072",total-size="9880"}
+download,{section=".text",section-sent="3584",section-size="6668",
total-sent="3584",total-size="9880"}
+download,{section=".text",section-sent="4096",section-size="6668",
total-sent="4096",total-size="9880"}
+download,{section=".text",section-sent="4608",section-size="6668",
total-sent="4608",total-size="9880"}
+download,{section=".text",section-sent="5120",section-size="6668",
total-sent="5120",total-size="9880"}
+download,{section=".text",section-sent="5632",section-size="6668",
total-sent="5632",total-size="9880"}
+download,{section=".text",section-sent="6144",section-size="6668",
total-sent="6144",total-size="9880"}
+download,{section=".text",section-sent="6656",section-size="6668",
total-sent="6656",total-size="9880"}
+download,{section=".init",section-size="28",total-size="9880"}
+download,{section=".fini",section-size="28",total-size="9880"}
+download,{section=".data",section-size="3156",total-size="9880"}
+download,{section=".data",section-sent="512",section-size="3156",
total-sent="7236",total-size="9880"}
+download,{section=".data",section-sent="1024",section-size="3156",
total-sent="7748",total-size="9880"}
+download,{section=".data",section-sent="1536",section-size="3156",
total-sent="8260",total-size="9880"}
+download,{section=".data",section-sent="2048",section-size="3156",
total-sent="8772",total-size="9880"}
+download,{section=".data",section-sent="2560",section-size="3156",
total-sent="9284",total-size="9880"}
+download,{section=".data",section-sent="3072",section-size="3156",
total-sent="9796",total-size="9880"}
^done,address="0x10004",load-size="9880",transfer-rate="6586",
write-rate="429"
(gdb)
The `-target-exec-status' Command
---------------------------------
Synopsis
........
-target-exec-status
Provide information on the state of the target (whether it is
running or not, for instance).
GDB Command
...........
There's no equivalent GDB command.
Example
.......
N.A.
The `-target-list-available-targets' Command
--------------------------------------------
Synopsis
........
-target-list-available-targets
List the possible targets to connect to.
GDB Command
...........
The corresponding GDB command is `help target'.
Example
.......
N.A.
The `-target-list-current-targets' Command
------------------------------------------
Synopsis
........
-target-list-current-targets
Describe the current target.
GDB Command
...........
The corresponding information is printed by `info file' (among other
things).
Example
.......
N.A.
The `-target-list-parameters' Command
-------------------------------------
Synopsis
........
-target-list-parameters
GDB Command
...........
No equivalent.
Example
.......
N.A.
The `-target-select' Command
----------------------------
Synopsis
........
-target-select TYPE PARAMETERS ...
Connect GDB to the remote target. This command takes two args:
`TYPE'
The type of target, for instance `async', `remote', etc.
`PARAMETERS'
Device names, host names and the like. *Note Commands for
managing targets: Target Commands, for more details.
The output is a connection notification, followed by the address at
which the target program is, in the following form:
^connected,addr="ADDRESS",func="FUNCTION NAME",
args=[ARG LIST]
GDB Command
...........
The corresponding GDB command is `target'.
Example
.......
(gdb)
-target-select async /dev/ttya
^connected,addr="0xfe00a300",func="??",args=[]
(gdb)
File: gdb.info, Node: GDB/MI Thread Commands, Next: GDB/MI Tracepoint Commands, Prev: GDB/MI Target Manipulation, Up: GDB/MI
GDB/MI Thread Commands
======================
The `-thread-info' Command
--------------------------
Synopsis
........
-thread-info
GDB command
...........
No equivalent.
Example
.......
N.A.
The `-thread-list-all-threads' Command
--------------------------------------
Synopsis
........
-thread-list-all-threads
GDB Command
...........
The equivalent GDB command is `info threads'.
Example
.......
N.A.
The `-thread-list-ids' Command
------------------------------
Synopsis
........
-thread-list-ids
Produces a list of the currently known GDB thread ids. At the end
of the list it also prints the total number of such threads.
GDB Command
...........
Part of `info threads' supplies the same information.
Example
.......
No threads present, besides the main process:
(gdb)
-thread-list-ids
^done,thread-ids={},number-of-threads="0"
(gdb)
Several threads:
(gdb)
-thread-list-ids
^done,thread-ids={thread-id="3",thread-id="2",thread-id="1"},
number-of-threads="3"
(gdb)
The `-thread-select' Command
----------------------------
Synopsis
........
-thread-select THREADNUM
Make THREADNUM the current thread. It prints the number of the new
current thread, and the topmost frame for that thread.
GDB Command
...........
The corresponding GDB command is `thread'.
Example
.......
(gdb)
-exec-next
^running
(gdb)
*stopped,reason="end-stepping-range",thread-id="2",line="187",
file="../../../devo/gdb/testsuite/gdb.threads/linux-dp.c"
(gdb)
-thread-list-ids
^done,
thread-ids={thread-id="3",thread-id="2",thread-id="1"},
number-of-threads="3"
(gdb)
-thread-select 3
^done,new-thread-id="3",
frame={level="0",func="vprintf",
args=[{name="format",value="0x8048e9c \"%*s%c %d %c\\n\""},
{name="arg",value="0x2"}],file="vprintf.c",line="31"}
(gdb)
File: gdb.info, Node: GDB/MI Tracepoint Commands, Next: GDB/MI Variable Objects, Prev: GDB/MI Thread Commands, Up: GDB/MI
GDB/MI Tracepoint Commands
==========================
The tracepoint commands are not yet implemented.
File: gdb.info, Node: GDB/MI Variable Objects, Prev: GDB/MI Tracepoint Commands, Up: GDB/MI
GDB/MI Variable Objects
=======================
Motivation for Variable Objects in GDB/MI
-----------------------------------------
For the implementation of a variable debugger window (locals, watched
expressions, etc.), we are proposing the adaptation of the existing code
used by `Insight'.
The two main reasons for that are:
1. It has been proven in practice (it is already on its second
generation).
2. It will shorten development time (needless to say how important it
is now).
The original interface was designed to be used by Tcl code, so it was
slightly changed so it could be used through GDB/MI. This section
describes the GDB/MI operations that will be available and gives some
hints about their use.
_Note_: In addition to the set of operations described here, we
expect the GUI implementation of a variable window to require, at
least, the following operations:
* `-gdb-show' `output-radix'
* `-stack-list-arguments'
* `-stack-list-locals'
* `-stack-select-frame'
Introduction to Variable Objects in GDB/MI
------------------------------------------
The basic idea behind variable objects is the creation of a named object
to represent a variable, an expression, a memory location or even a CPU
register. For each object created, a set of operations is available for
examining or changing its properties.
Furthermore, complex data types, such as C structures, are
represented in a tree format. For instance, the `struct' type variable
is the root and the children will represent the struct members. If a
child is itself of a complex type, it will also have children of its
own. Appropriate language differences are handled for C, C++ and Java.
When returning the actual values of the objects, this facility allows
for the individual selection of the display format used in the result
creation. It can be chosen among: binary, decimal, hexadecimal, octal
and natural. Natural refers to a default format automatically chosen
based on the variable type (like decimal for an `int', hex for
pointers, etc.).
The following is the complete set of GDB/MI operations defined to
access this functionality:
*Operation* *Description*
`-var-create' create a variable object
`-var-delete' delete the variable object and its children
`-var-set-format' set the display format of this variable
`-var-show-format' show the display format of this variable
`-var-info-num-children' tells how many children this object has
`-var-list-children' return a list of the object's children
`-var-info-type' show the type of this variable object
`-var-info-expression' print what this variable object represents
`-var-show-attributes' is this variable editable? does it exist
here?
`-var-evaluate-expression' get the value of this variable
`-var-assign' set the value of this variable
`-var-update' update the variable and its children
In the next subsection we describe each operation in detail and
suggest how it can be used.
Description And Use of Operations on Variable Objects
-----------------------------------------------------
The `-var-create' Command
-------------------------
Synopsis
........
-var-create {NAME | "-"}
{FRAME-ADDR | "*"} EXPRESSION
This operation creates a variable object, which allows the
monitoring of a variable, the result of an expression, a memory cell or
a CPU register.
The NAME parameter is the string by which the object can be
referenced. It must be unique. If `-' is specified, the varobj system
will generate a string "varNNNNNN" automatically. It will be unique
provided that one does not specify NAME on that format. The command
fails if a duplicate name is found.
The frame under which the expression should be evaluated can be
specified by FRAME-ADDR. A `*' indicates that the current frame should
be used.
EXPRESSION is any expression valid on the current language set (must
not begin with a `*'), or one of the following:
* `*ADDR', where ADDR is the address of a memory cell
* `*ADDR-ADDR' -- a memory address range (TBD)
* `$REGNAME' -- a CPU register name
Result
......
This operation returns the name, number of children and the type of the
object created. Type is returned as a string as the ones generated by
the GDB CLI:
name="NAME",numchild="N",type="TYPE"
The `-var-delete' Command
-------------------------
Synopsis
........
-var-delete NAME
Deletes a previously created variable object and all of its children.
Returns an error if the object NAME is not found.
The `-var-set-format' Command
-----------------------------
Synopsis
........
-var-set-format NAME FORMAT-SPEC
Sets the output format for the value of the object NAME to be
FORMAT-SPEC.
The syntax for the FORMAT-SPEC is as follows:
FORMAT-SPEC ==>
{binary | decimal | hexadecimal | octal | natural}
The `-var-show-format' Command
------------------------------
Synopsis
........
-var-show-format NAME
Returns the format used to display the value of the object NAME.
FORMAT ==>
FORMAT-SPEC
The `-var-info-num-children' Command
------------------------------------
Synopsis
........
-var-info-num-children NAME
Returns the number of children of a variable object NAME:
numchild=N
The `-var-list-children' Command
--------------------------------
Synopsis
........
-var-list-children [PRINT-VALUES] NAME
Returns a list of the children of the specified variable object.
With just the variable object name as an argument or with an optional
preceding argument of 0 or `--no-values', prints only the names of the
variables. With an optional preceding argument of 1 or `--all-values',
also prints their values.
Example
.......
(gdb)
-var-list-children n
numchild=N,children=[{name=NAME,
numchild=N,type=TYPE},(repeats N times)]
(gdb)
-var-list-children --all-values n
numchild=N,children=[{name=NAME,
numchild=N,value=VALUE,type=TYPE},(repeats N times)]
The `-var-info-type' Command
----------------------------
Synopsis
........
-var-info-type NAME
Returns the type of the specified variable NAME. The type is
returned as a string in the same format as it is output by the GDB CLI:
type=TYPENAME
The `-var-info-expression' Command
----------------------------------
Synopsis
........
-var-info-expression NAME
Returns what is represented by the variable object NAME:
lang=LANG-SPEC,exp=EXPRESSION
where LANG-SPEC is `{"C" | "C++" | "Java"}'.
The `-var-show-attributes' Command
----------------------------------
Synopsis
........
-var-show-attributes NAME
List attributes of the specified variable object NAME:
status=ATTR [ ( ,ATTR )* ]
where ATTR is `{ { editable | noneditable } | TBD }'.
The `-var-evaluate-expression' Command
--------------------------------------
Synopsis
........
-var-evaluate-expression NAME
Evaluates the expression that is represented by the specified
variable object and returns its value as a string in the current format
specified for the object:
value=VALUE
Note that one must invoke `-var-list-children' for a variable before
the value of a child variable can be evaluated.
The `-var-assign' Command
-------------------------
Synopsis
........
-var-assign NAME EXPRESSION
Assigns the value of EXPRESSION to the variable object specified by
NAME. The object must be `editable'. If the variable's value is
altered by the assign, the variable will show up in any subsequent
`-var-update' list.
Example
.......
(gdb)
-var-assign var1 3
^done,value="3"
(gdb)
-var-update *
^done,changelist=[{name="var1",in_scope="true",type_changed="false"}]
(gdb)
The `-var-update' Command
-------------------------
Synopsis
........
-var-update {NAME | "*"}
Update the value of the variable object NAME by evaluating its
expression after fetching all the new values from memory or registers.
A `*' causes all existing variable objects to be updated.
File: gdb.info, Node: Annotations, Next: GDB/MI, Prev: Emacs, Up: Top
GDB Annotations
***************
This chapter describes annotations in GDB. Annotations were designed
to interface GDB to graphical user interfaces or other similar programs
which want to interact with GDB at a relatively high level.
The annotation mechanism has largely been superseeded by GDB/MI
(*note GDB/MI::).
* Menu:
* Annotations Overview:: What annotations are; the general syntax.
* Server Prefix:: Issuing a command without affecting user state.
* Prompting:: Annotations marking GDB's need for input.
* Errors:: Annotations for error messages.
* Invalidation:: Some annotations describe things now invalid.
* Annotations for Running::
Whether the program is running, how it stopped, etc.
* Source Annotations:: Annotations describing source code.
File: gdb.info, Node: Annotations Overview, Next: Server Prefix, Up: Annotations
What is an Annotation?
======================
Annotations start with a newline character, two `control-z' characters,
and the name of the annotation. If there is no additional information
associated with this annotation, the name of the annotation is followed
immediately by a newline. If there is additional information, the name
of the annotation is followed by a space, the additional information,
and a newline. The additional information cannot contain newline
characters.
Any output not beginning with a newline and two `control-z'
characters denotes literal output from GDB. Currently there is no need
for GDB to output a newline followed by two `control-z' characters, but
if there was such a need, the annotations could be extended with an
`escape' annotation which means those three characters as output.
The annotation LEVEL, which is specified using the `--annotate'
command line option (*note Mode Options::), controls how much
information GDB prints together with its prompt, values of expressions,
source lines, and other types of output. Level 0 is for no anntations,
level 1 is for use when GDB is run as a subprocess of GNU Emacs, level
3 is the maximum annotation suitable for programs that control GDB, and
level 2 annotations have been made obsolete (*note Limitations of the
Annotation Interface: (annotate)Limitations.). This chapter describes
level 3 annotations.
A simple example of starting up GDB with annotations is:
$ gdb --annotate=3
GNU gdb 6.0
Copyright 2003 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License,
and you are welcome to change it and/or distribute copies of it
under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty"
for details.
This GDB was configured as "i386-pc-linux-gnu"
^Z^Zpre-prompt
(gdb)
^Z^Zprompt
quit
^Z^Zpost-prompt
$
Here `quit' is input to GDB; the rest is output from GDB. The three
lines beginning `^Z^Z' (where `^Z' denotes a `control-z' character) are
annotations; the rest is output from GDB.
File: gdb.info, Node: Server Prefix, Next: Prompting, Prev: Annotations Overview, Up: Annotations
The Server Prefix
=================
To issue a command to GDB without affecting certain aspects of the
state which is seen by users, prefix it with `server '. This means
that this command will not affect the command history, nor will it
affect GDB's notion of which command to repeat if <RET> is pressed on a
line by itself.
The server prefix does not affect the recording of values into the
value history; to print a value without recording it into the value
history, use the `output' command instead of the `print' command.
File: gdb.info, Node: Prompting, Next: Errors, Prev: Server Prefix, Up: Annotations
Annotation for GDB Input
========================
When GDB prompts for input, it annotates this fact so it is possible to
know when to send output, when the output from a given command is over,
etc.
Different kinds of input each have a different "input type". Each
input type has three annotations: a `pre-' annotation, which denotes
the beginning of any prompt which is being output, a plain annotation,
which denotes the end of the prompt, and then a `post-' annotation
which denotes the end of any echo which may (or may not) be associated
with the input. For example, the `prompt' input type features the
following annotations:
^Z^Zpre-prompt
^Z^Zprompt
^Z^Zpost-prompt
The input types are
`prompt'
When GDB is prompting for a command (the main GDB prompt).
`commands'
When GDB prompts for a set of commands, like in the `commands'
command. The annotations are repeated for each command which is
input.
`overload-choice'
When GDB wants the user to select between various overloaded
functions.
`query'
When GDB wants the user to confirm a potentially dangerous
operation.
`prompt-for-continue'
When GDB is asking the user to press return to continue. Note:
Don't expect this to work well; instead use `set height 0' to
disable prompting. This is because the counting of lines is buggy
in the presence of annotations.
File: gdb.info, Node: Errors, Next: Invalidation, Prev: Prompting, Up: Annotations
Errors
======
^Z^Zquit
This annotation occurs right before GDB responds to an interrupt.
^Z^Zerror
This annotation occurs right before GDB responds to an error.
Quit and error annotations indicate that any annotations which GDB
was in the middle of may end abruptly. For example, if a
`value-history-begin' annotation is followed by a `error', one cannot
expect to receive the matching `value-history-end'. One cannot expect
not to receive it either, however; an error annotation does not
necessarily mean that GDB is immediately returning all the way to the
top level.
A quit or error annotation may be preceded by
^Z^Zerror-begin
Any output between that and the quit or error annotation is the error
message.
Warning messages are not yet annotated.
File: gdb.info, Node: Invalidation, Next: Annotations for Running, Prev: Errors, Up: Annotations
Invalidation Notices
====================
The following annotations say that certain pieces of state may have
changed.
`^Z^Zframes-invalid'
The frames (for example, output from the `backtrace' command) may
have changed.
`^Z^Zbreakpoints-invalid'
The breakpoints may have changed. For example, the user just
added or deleted a breakpoint.
File: gdb.info, Node: Annotations for Running, Next: Source Annotations, Prev: Invalidation, Up: Annotations
Running the Program
===================
When the program starts executing due to a GDB command such as `step'
or `continue',
^Z^Zstarting
is output. When the program stops,
^Z^Zstopped
is output. Before the `stopped' annotation, a variety of
annotations describe how the program stopped.
`^Z^Zexited EXIT-STATUS'
The program exited, and EXIT-STATUS is the exit status (zero for
successful exit, otherwise nonzero).
`^Z^Zsignalled'
The program exited with a signal. After the `^Z^Zsignalled', the
annotation continues:
INTRO-TEXT
^Z^Zsignal-name
NAME
^Z^Zsignal-name-end
MIDDLE-TEXT
^Z^Zsignal-string
STRING
^Z^Zsignal-string-end
END-TEXT
where NAME is the name of the signal, such as `SIGILL' or
`SIGSEGV', and STRING is the explanation of the signal, such as
`Illegal Instruction' or `Segmentation fault'. INTRO-TEXT,
MIDDLE-TEXT, and END-TEXT are for the user's benefit and have no
particular format.
`^Z^Zsignal'
The syntax of this annotation is just like `signalled', but GDB is
just saying that the program received the signal, not that it was
terminated with it.
`^Z^Zbreakpoint NUMBER'
The program hit breakpoint number NUMBER.
`^Z^Zwatchpoint NUMBER'
The program hit watchpoint number NUMBER.
File: gdb.info, Node: Source Annotations, Prev: Annotations for Running, Up: Annotations
Displaying Source
=================
The following annotation is used instead of displaying source code:
^Z^Zsource FILENAME:LINE:CHARACTER:MIDDLE:ADDR
where FILENAME is an absolute file name indicating which source
file, LINE is the line number within that file (where 1 is the first
line in the file), CHARACTER is the character position within the file
(where 0 is the first character in the file) (for most debug formats
this will necessarily point to the beginning of a line), MIDDLE is
`middle' if ADDR is in the middle of the line, or `beg' if ADDR is at
the beginning of the line, and ADDR is the address in the target
program associated with the source which is being displayed. ADDR is
in the form `0x' followed by one or more lowercase hex digits (note
that this does not depend on the language).
File: gdb.info, Node: GDB Bugs, Next: Formatting Documentation, Prev: GDB/MI, Up: Top
Reporting Bugs in GDB
*********************
Your bug reports play an essential role in making GDB reliable.
Reporting a bug may help you by bringing a solution to your problem,
or it may not. But in any case the principal function of a bug report
is to help the entire community by making the next version of GDB work
better. Bug reports are your contribution to the maintenance of GDB.
In order for a bug report to serve its purpose, you must include the
information that enables us to fix the bug.
* Menu:
* Bug Criteria:: Have you found a bug?
* Bug Reporting:: How to report bugs
File: gdb.info, Node: Bug Criteria, Next: Bug Reporting, Up: GDB Bugs
Have you found a bug?
=====================
If you are not sure whether you have found a bug, here are some
guidelines:
* If the debugger gets a fatal signal, for any input whatever, that
is a GDB bug. Reliable debuggers never crash.
* If GDB produces an error message for valid input, that is a bug.
(Note that if you're cross debugging, the problem may also be
somewhere in the connection to the target.)
* If GDB does not produce an error message for invalid input, that
is a bug. However, you should note that your idea of "invalid
input" might be our idea of "an extension" or "support for
traditional practice".
* If you are an experienced user of debugging tools, your suggestions
for improvement of GDB are welcome in any case.
File: gdb.info, Node: Bug Reporting, Prev: Bug Criteria, Up: GDB Bugs
How to report bugs
==================
A number of companies and individuals offer support for GNU products.
If you obtained GDB from a support organization, we recommend you
contact that organization first.
You can find contact information for many support companies and
individuals in the file `etc/SERVICE' in the GNU Emacs distribution.
In any event, we also recommend that you submit bug reports for GDB.
The prefered method is to submit them directly using GDB's Bugs web
page (http://www.gnu.org/software/gdb/bugs/). Alternatively, the
e-mail gateway <bug-gdb@gnu.org> can be used.
*Do not send bug reports to `info-gdb', or to `help-gdb', or to any
newsgroups.* Most users of GDB do not want to receive bug reports.
Those that do have arranged to receive `bug-gdb'.
The mailing list `bug-gdb' has a newsgroup `gnu.gdb.bug' which
serves as a repeater. The mailing list and the newsgroup carry exactly
the same messages. Often people think of posting bug reports to the
newsgroup instead of mailing them. This appears to work, but it has one
problem which can be crucial: a newsgroup posting often lacks a mail
path back to the sender. Thus, if we need to ask for more information,
we may be unable to reach you. For this reason, it is better to send
bug reports to the mailing list.
The fundamental principle of reporting bugs usefully is this:
*report all the facts*. If you are not sure whether to state a fact or
leave it out, state it!
Often people omit facts because they think they know what causes the
problem and assume that some details do not matter. Thus, you might
assume that the name of the variable you use in an example does not
matter. Well, probably it does not, but one cannot be sure. Perhaps
the bug is a stray memory reference which happens to fetch from the
location where that name is stored in memory; perhaps, if the name were
different, the contents of that location would fool the debugger into
doing the right thing despite the bug. Play it safe and give a
specific, complete example. That is the easiest thing for you to do,
and the most helpful.
Keep in mind that the purpose of a bug report is to enable us to fix
the bug. It may be that the bug has been reported previously, but
neither you nor we can know that unless your bug report is complete and
self-contained.
Sometimes people give a few sketchy facts and ask, "Does this ring a
bell?" Those bug reports are useless, and we urge everyone to _refuse
to respond to them_ except to chide the sender to report bugs properly.
To enable us to fix the bug, you should include all these things:
* The version of GDB. GDB announces it if you start with no
arguments; you can also print it at any time using `show version'.
Without this, we will not know whether there is any point in
looking for the bug in the current version of GDB.
* The type of machine you are using, and the operating system name
and version number.
* What compiler (and its version) was used to compile GDB--e.g.
"gcc-2.8.1".
* What compiler (and its version) was used to compile the program
you are debugging--e.g. "gcc-2.8.1", or "HP92453-01 A.10.32.03 HP
C Compiler". For GCC, you can say `gcc --version' to get this
information; for other compilers, see the documentation for those
compilers.
* The command arguments you gave the compiler to compile your
example and observe the bug. For example, did you use `-O'? To
guarantee you will not omit something important, list them all. A
copy of the Makefile (or the output from make) is sufficient.
If we were to try to guess the arguments, we would probably guess
wrong and then we might not encounter the bug.
* A complete input script, and all necessary source files, that will
reproduce the bug.
* A description of what behavior you observe that you believe is
incorrect. For example, "It gets a fatal signal."
Of course, if the bug is that GDB gets a fatal signal, then we
will certainly notice it. But if the bug is incorrect output, we
might not notice unless it is glaringly wrong. You might as well
not give us a chance to make a mistake.
Even if the problem you experience is a fatal signal, you should
still say so explicitly. Suppose something strange is going on,
such as, your copy of GDB is out of synch, or you have encountered
a bug in the C library on your system. (This has happened!) Your
copy might crash and ours would not. If you told us to expect a
crash, then when ours fails to crash, we would know that the bug
was not happening for us. If you had not told us to expect a
crash, then we would not be able to draw any conclusion from our
observations.
* If you wish to suggest changes to the GDB source, send us context
diffs. If you even discuss something in the GDB source, refer to
it by context, not by line number.
The line numbers in our development sources will not match those
in your sources. Your line numbers would convey no useful
information to us.
Here are some things that are not necessary:
* A description of the envelope of the bug.
Often people who encounter a bug spend a lot of time investigating
which changes to the input file will make the bug go away and which
changes will not affect it.
This is often time consuming and not very useful, because the way
we will find the bug is by running a single example under the
debugger with breakpoints, not by pure deduction from a series of
examples. We recommend that you save your time for something else.
Of course, if you can find a simpler example to report _instead_
of the original one, that is a convenience for us. Errors in the
output will be easier to spot, running under the debugger will take
less time, and so on.
However, simplification is not vital; if you do not want to do
this, report the bug anyway and send us the entire test case you
used.
* A patch for the bug.
A patch for the bug does help us if it is a good one. But do not
omit the necessary information, such as the test case, on the
assumption that a patch is all we need. We might see problems
with your patch and decide to fix the problem another way, or we
might not understand it at all.
Sometimes with a program as complicated as GDB it is very hard to
construct an example that will make the program follow a certain
path through the code. If you do not send us the example, we will
not be able to construct one, so we will not be able to verify
that the bug is fixed.
And if we cannot understand what bug you are trying to fix, or why
your patch should be an improvement, we will not install it. A
test case will help us to understand.
* A guess about what the bug is or what it depends on.
Such guesses are usually wrong. Even we cannot guess right about
such things without first using the debugger to find the facts.
File: gdb.info, Node: Command Line Editing, Next: Using History Interactively, Prev: Formatting Documentation, Up: Top
Command Line Editing
********************
This chapter describes the basic features of the GNU command line
editing interface.
* Menu:
* Introduction and Notation:: Notation used in this text.
* Readline Interaction:: The minimum set of commands for editing a line.
* Readline Init File:: Customizing Readline from a user's view.
* Bindable Readline Commands:: A description of most of the Readline commands
available for binding
* Readline vi Mode:: A short description of how to make Readline
behave like the vi editor.
File: gdb.info, Node: Introduction and Notation, Next: Readline Interaction, Up: Command Line Editing
Introduction to Line Editing
============================
The following paragraphs describe the notation used to represent
keystrokes.
The text `C-k' is read as `Control-K' and describes the character
produced when the <k> key is pressed while the Control key is depressed.
The text `M-k' is read as `Meta-K' and describes the character
produced when the Meta key (if you have one) is depressed, and the <k>
key is pressed. The Meta key is labeled <ALT> on many keyboards. On
keyboards with two keys labeled <ALT> (usually to either side of the
space bar), the <ALT> on the left side is generally set to work as a
Meta key. The <ALT> key on the right may also be configured to work as
a Meta key or may be configured as some other modifier, such as a
Compose key for typing accented characters.
If you do not have a Meta or <ALT> key, or another key working as a
Meta key, the identical keystroke can be generated by typing <ESC>
_first_, and then typing <k>. Either process is known as "metafying"
the <k> key.
The text `M-C-k' is read as `Meta-Control-k' and describes the
character produced by "metafying" `C-k'.
In addition, several keys have their own names. Specifically,
<DEL>, <ESC>, <LFD>, <SPC>, <RET>, and <TAB> all stand for themselves
when seen in this text, or in an init file (*note Readline Init File::).
If your keyboard lacks a <LFD> key, typing <C-j> will produce the
desired character. The <RET> key may be labeled <Return> or <Enter> on
some keyboards.
File: gdb.info, Node: Readline Interaction, Next: Readline Init File, Prev: Introduction and Notation, Up: Command Line Editing
Readline Interaction
====================
Often during an interactive session you type in a long line of text,
only to notice that the first word on the line is misspelled. The
Readline library gives you a set of commands for manipulating the text
as you type it in, allowing you to just fix your typo, and not forcing
you to retype the majority of the line. Using these editing commands,
you move the cursor to the place that needs correction, and delete or
insert the text of the corrections. Then, when you are satisfied with
the line, you simply press <RET>. You do not have to be at the end of
the line to press <RET>; the entire line is accepted regardless of the
location of the cursor within the line.
* Menu:
* Readline Bare Essentials:: The least you need to know about Readline.
* Readline Movement Commands:: Moving about the input line.
* Readline Killing Commands:: How to delete text, and how to get it back!
* Readline Arguments:: Giving numeric arguments to commands.
* Searching:: Searching through previous lines.
File: gdb.info, Node: Readline Bare Essentials, Next: Readline Movement Commands, Up: Readline Interaction
Readline Bare Essentials
------------------------
In order to enter characters into the line, simply type them. The typed
character appears where the cursor was, and then the cursor moves one
space to the right. If you mistype a character, you can use your erase
character to back up and delete the mistyped character.
Sometimes you may mistype a character, and not notice the error
until you have typed several other characters. In that case, you can
type `C-b' to move the cursor to the left, and then correct your
mistake. Afterwards, you can move the cursor to the right with `C-f'.
When you add text in the middle of a line, you will notice that
characters to the right of the cursor are `pushed over' to make room
for the text that you have inserted. Likewise, when you delete text
behind the cursor, characters to the right of the cursor are `pulled
back' to fill in the blank space created by the removal of the text. A
list of the bare essentials for editing the text of an input line
follows.
`C-b'
Move back one character.
`C-f'
Move forward one character.
<DEL> or <Backspace>
Delete the character to the left of the cursor.
`C-d'
Delete the character underneath the cursor.
Printing characters
Insert the character into the line at the cursor.
`C-_' or `C-x C-u'
Undo the last editing command. You can undo all the way back to an
empty line.
(Depending on your configuration, the <Backspace> key be set to delete
the character to the left of the cursor and the <DEL> key set to delete
the character underneath the cursor, like `C-d', rather than the
character to the left of the cursor.)
File: gdb.info, Node: Readline Movement Commands, Next: Readline Killing Commands, Prev: Readline Bare Essentials, Up: Readline Interaction
Readline Movement Commands
--------------------------
The above table describes the most basic keystrokes that you need in
order to do editing of the input line. For your convenience, many
other commands have been added in addition to `C-b', `C-f', `C-d', and
<DEL>. Here are some commands for moving more rapidly about the line.
`C-a'
Move to the start of the line.
`C-e'
Move to the end of the line.
`M-f'
Move forward a word, where a word is composed of letters and
digits.
`M-b'
Move backward a word.
`C-l'
Clear the screen, reprinting the current line at the top.
Notice how `C-f' moves forward a character, while `M-f' moves
forward a word. It is a loose convention that control keystrokes
operate on characters while meta keystrokes operate on words.
File: gdb.info, Node: Readline Killing Commands, Next: Readline Arguments, Prev: Readline Movement Commands, Up: Readline Interaction
Readline Killing Commands
-------------------------
"Killing" text means to delete the text from the line, but to save it
away for later use, usually by "yanking" (re-inserting) it back into
the line. (`Cut' and `paste' are more recent jargon for `kill' and
`yank'.)
If the description for a command says that it `kills' text, then you
can be sure that you can get the text back in a different (or the same)
place later.
When you use a kill command, the text is saved in a "kill-ring".
Any number of consecutive kills save all of the killed text together, so
that when you yank it back, you get it all. The kill ring is not line
specific; the text that you killed on a previously typed line is
available to be yanked back later, when you are typing another line.
Here is the list of commands for killing text.
`C-k'
Kill the text from the current cursor position to the end of the
line.
`M-d'
Kill from the cursor to the end of the current word, or, if between
words, to the end of the next word. Word boundaries are the same
as those used by `M-f'.
`M-<DEL>'
Kill from the cursor the start of the current word, or, if between
words, to the start of the previous word. Word boundaries are the
same as those used by `M-b'.
`C-w'
Kill from the cursor to the previous whitespace. This is
different than `M-<DEL>' because the word boundaries differ.
Here is how to "yank" the text back into the line. Yanking means to
copy the most-recently-killed text from the kill buffer.
`C-y'
Yank the most recently killed text back into the buffer at the
cursor.
`M-y'
Rotate the kill-ring, and yank the new top. You can only do this
if the prior command is `C-y' or `M-y'.
File: gdb.info, Node: Readline Arguments, Next: Searching, Prev: Readline Killing Commands, Up: Readline Interaction
Readline Arguments
------------------
You can pass numeric arguments to Readline commands. Sometimes the
argument acts as a repeat count, other times it is the sign of the
argument that is significant. If you pass a negative argument to a
command which normally acts in a forward direction, that command will
act in a backward direction. For example, to kill text back to the
start of the line, you might type `M-- C-k'.
The general way to pass numeric arguments to a command is to type
meta digits before the command. If the first `digit' typed is a minus
sign (`-'), then the sign of the argument will be negative. Once you
have typed one meta digit to get the argument started, you can type the
remainder of the digits, and then the command. For example, to give
the `C-d' command an argument of 10, you could type `M-1 0 C-d', which
will delete the next ten characters on the input line.