| Current Path : /sys/boot/i386/zfsboot/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //sys/boot/i386/zfsboot/zfsldr.S |
/* * Copyright (c) 1998 Robert Nordier * All rights reserved. * * Redistribution and use in source and binary forms are freely * permitted provided that the above copyright notice and this * paragraph and the following disclaimer are duplicated in all * such forms. * * This software is provided "AS IS" and without any express or * implied warranties, including, without limitation, the implied * warranties of merchantability and fitness for a particular * purpose. * * $FreeBSD: release/9.1.0/sys/boot/i386/zfsboot/zfsldr.S 223611 2011-06-27 21:43:56Z jhb $ */ /* Memory Locations */ .set MEM_ARG,0x900 # Arguments .set MEM_ORG,0x7c00 # Origin .set MEM_BUF,0x8000 # Load area .set MEM_BTX,0x9000 # BTX start .set MEM_JMP,0x9010 # BTX entry point .set MEM_USR,0xa000 # Client start .set BDA_BOOT,0x472 # Boot howto flag /* Partition Constants */ .set PRT_OFF,0x1be # Partition offset .set PRT_NUM,0x4 # Partitions .set PRT_BSD,0xa5 # Partition type /* Misc. Constants */ .set SIZ_PAG,0x1000 # Page size .set SIZ_SEC,0x200 # Sector size .set NSECT,0x80 .globl start .code16 /* * Load the rest of zfsboot2 and BTX up, copy the parts to the right locations, * and start it all up. */ /* * Setup the segment registers to flat addressing (segment 0) and setup the * stack to end just below the start of our code. */ start: cld # String ops inc xor %cx,%cx # Zero mov %cx,%es # Address mov %cx,%ds # data mov %cx,%ss # Set up mov $start,%sp # stack /* * Load the MBR and look for the first FreeBSD slice. We use the fake * partition entry below that points to the MBR when we call read. * The first pass looks for the first active FreeBSD slice. The * second pass looks for the first non-active FreeBSD slice if the * first one fails. */ call check_edd # Make sure EDD works mov $part4,%si # Dummy partition xor %eax,%eax # Read MBR movl $MEM_BUF,%ebx # from first call read # sector mov $0x1,%cx # Two passes main.1: mov $MEM_BUF+PRT_OFF,%si # Partition table movb $0x1,%dh # Partition main.2: cmpb $PRT_BSD,0x4(%si) # Our partition type? jne main.3 # No jcxz main.5 # If second pass testb $0x80,(%si) # Active? jnz main.5 # Yes main.3: add $0x10,%si # Next entry incb %dh # Partition cmpb $0x1+PRT_NUM,%dh # In table? jb main.2 # Yes dec %cx # Do two jcxz main.1 # passes /* * If we get here, we didn't find any FreeBSD slices at all, so print an * error message and die. */ mov $msg_part,%si # Message jmp error # Error /* * Ok, we have a slice and drive in %dx now, so use that to locate and * load boot2. %si references the start of the slice we are looking * for, so go ahead and load up the 128 sectors starting at sector 1024 * (i.e. after the two vdev labels). We don't have do anything fancy * here to allow for an extra copy of boot1 and a partition table * (compare to this section of the UFS bootstrap) so we just load it * all at 0x9000. The first part of boot2 is BTX, which wants to run * at 0x9000. The boot2.bin binary starts right after the end of BTX, * so we have to figure out where the start of it is and then move the * binary to 0xc000. Normally, BTX clients start at MEM_USR, or 0xa000, * but when we use btxld to create zfsboot2, we use an entry point of * 0x2000. That entry point is relative to MEM_USR; thus boot2.bin * starts at 0xc000. * * The load area and the target area for the client overlap so we have * to use a decrementing string move. We also play segment register * games with the destination address for the move so that the client * can be larger than 16k (which would overflow the zero segment since * the client starts at 0xc000). */ main.5: mov %dx,MEM_ARG # Save args mov $NSECT,%cx # Sector count movl $1024,%eax # Offset to boot2 mov $MEM_BTX,%ebx # Destination buffer main.6: pushal # Save params call read # Read disk popal # Restore incl %eax # Advance to add $SIZ_SEC,%ebx # next sector loop main.6 # If not last, read another mov MEM_BTX+0xa,%bx # Get BTX length mov $NSECT*SIZ_SEC-1,%di # Size of load area (less one) mov %di,%si # End of load area, 0x9000 rel sub %bx,%di # End of client, 0xc000 rel mov %di,%cx # Size of inc %cx # client mov $(MEM_BTX)>>4,%dx # Segment mov %dx,%ds # addressing 0x9000 mov $(MEM_USR+2*SIZ_PAG)>>4,%dx # Segment mov %dx,%es # addressing 0xc000 std # Move with decrement rep # Relocate movsb # client cld # Back to increment xor %dx,%dx # Back mov %ds,%dx # to zero mov %dx,%es # segment /* * Enable A20 so we can access memory above 1 meg. * Use the zero-valued %cx as a timeout for embedded hardware which do not * have a keyboard controller. */ seta20: cli # Disable interrupts seta20.1: dec %cx # Timeout? jz seta20.3 # Yes inb $0x64,%al # Get status testb $0x2,%al # Busy? jnz seta20.1 # Yes movb $0xd1,%al # Command: Write outb %al,$0x64 # output port seta20.2: inb $0x64,%al # Get status testb $0x2,%al # Busy? jnz seta20.2 # Yes movb $0xdf,%al # Enable outb %al,$0x60 # A20 seta20.3: sti # Enable interrupts jmp start+MEM_JMP-MEM_ORG # Start BTX /* * Read a sector from the disk. Sets up an EDD packet on the stack * and passes it to read. We assume that the destination address is * always segment-aligned. * * %eax - int - LBA to read in relative to partition start * %ebx - ptr - destination address * %dl - byte - drive to read from * %si - ptr - MBR partition entry */ read: xor %ecx,%ecx # Get addl 0x8(%si),%eax # LBA adc $0,%ecx pushl %ecx # Starting absolute block pushl %eax # block number shr $4,%ebx # Convert to segment push %bx # Address of push $0 # transfer buffer push $0x1 # Read 1 sector push $0x10 # Size of packet mov %sp,%si # Packet pointer mov $0x42,%ah # BIOS: Extended int $0x13 # read jc read.1 # If error, fail lea 0x10(%si),%sp # Clear stack ret # If success, return read.1: mov %ah,%al # Format mov $read_err,%di # error call hex8 # code mov $msg_read,%si # Set the error message and # fall through to the error # routine /* * Print out the error message pointed to by %ds:(%si) followed * by a prompt, wait for a keypress, and then reboot the machine. */ error: callw putstr # Display message mov $prompt,%si # Display callw putstr # prompt xorb %ah,%ah # BIOS: Get int $0x16 # keypress movw $0x1234, BDA_BOOT # Do a warm boot ljmp $0xffff,$0x0 # reboot the machine /* * Display a null-terminated string using the BIOS output. */ putstr.0: mov $0x7,%bx # Page:attribute movb $0xe,%ah # BIOS: Display int $0x10 # character putstr: lodsb # Get char testb %al,%al # End of string? jne putstr.0 # No ret # To caller /* * Check to see if the disk supports EDD. zfsboot requires EDD and does not * support older C/H/S disk I/O. */ check_edd: cmpb $0x80,%dl # Hard drive? jb check_edd.1 # No, fail to boot mov $0x55aa,%bx # Magic push %dx # Save movb $0x41,%ah # BIOS: Check int $0x13 # extensions present pop %dx # Restore jc check_edd.1 # If error, fail cmp $0xaa55,%bx # Magic? jne check_edd.1 # No, so fail testb $0x1,%cl # Packet interface? jz check_edd.1 # No, so fail ret # EDD ok, keep booting check_edd.1: mov $msg_chs,%si # Warn that CHS is jmp error # unsupported and fail /* * AL to hex, saving the result to [EDI]. */ hex8: push %ax # Save shrb $0x4,%al # Do upper call hex8.1 # 4 pop %ax # Restore hex8.1: andb $0xf,%al # Get lower 4 cmpb $0xa,%al # Convert sbbb $0x69,%al # to hex das # digit orb $0x20,%al # To lower case stosb # Save char ret # (Recursive) /* Messages */ msg_chs: .asciz "CHS not supported" msg_read: .ascii "Read error: " read_err: .asciz "XX" msg_part: .asciz "Boot error" prompt: .asciz "\r\n" .org PRT_OFF,0x90 /* Partition table */ .fill 0x30,0x1,0x0 part4: .byte 0x80, 0x00, 0x01, 0x00 .byte 0xa5, 0xfe, 0xff, 0xff .byte 0x00, 0x00, 0x00, 0x00 .byte 0x50, 0xc3, 0x00, 0x00 # 50000 sectors long, bleh .word 0xaa55 # Magic number