diff options
Diffstat (limited to 'contrib/syslinux/syslinux-4.03/mbr/mbr.S')
| -rw-r--r-- | contrib/syslinux/syslinux-4.03/mbr/mbr.S | 299 |
1 files changed, 0 insertions, 299 deletions
diff --git a/contrib/syslinux/syslinux-4.03/mbr/mbr.S b/contrib/syslinux/syslinux-4.03/mbr/mbr.S deleted file mode 100644 index 7caf4fc..0000000 --- a/contrib/syslinux/syslinux-4.03/mbr/mbr.S +++ /dev/null @@ -1,299 +0,0 @@ -/* ----------------------------------------------------------------------- - * - * Copyright 2007-2009 H. Peter Anvin - All Rights Reserved - * Copyright 2009 Intel Corporation; author: H. Peter Anvin - * - * Permission is hereby granted, free of charge, to any person - * obtaining a copy of this software and associated documentation - * files (the "Software"), to deal in the Software without - * restriction, including without limitation the rights to use, - * copy, modify, merge, publish, distribute, sublicense, and/or - * sell copies of the Software, and to permit persons to whom - * the Software is furnished to do so, subject to the following - * conditions: - * - * The above copyright notice and this permission notice shall - * be included in all copies or substantial portions of the Software. - * - * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, - * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES - * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND - * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT - * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, - * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING - * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR - * OTHER DEALINGS IN THE SOFTWARE. - * - * ----------------------------------------------------------------------- */ - -#include "adjust.h" - - .code16 - .text - - .globl bootsec -stack = 0x7c00 -driveno = (stack-6) -sectors = (stack-8) -secpercyl = (stack-12) - -BIOS_kbdflags = 0x417 -BIOS_page = 0x462 - - /* gas/ld has issues with doing this as absolute addresses... */ - .section ".bootsec", "a", @nobits - .globl bootsec -bootsec: - .space 512 - - .text - .globl _start -_start: - cli - xorw %ax, %ax - movw %ax, %ds - movw %ax, %ss - movw $stack, %sp - movw %sp, %si - pushw %es /* es:di -> $PnP header */ - pushw %di - movw %ax, %es - sti - cld - - /* Copy down to 0:0x600 */ - movw $_start, %di - movw $(512/2), %cx - rep; movsw - - ljmpw $0, $next -next: - - ADJUST_DRIVE - pushw %dx /* dl -> drive number */ - - /* Check to see if we have EBIOS */ - pushw %dx /* drive number */ - movb $0x41, %ah /* %al == 0 already */ - movw $0x55aa, %bx - xorw %cx, %cx - xorb %dh, %dh - stc - int $0x13 - jc 1f - cmpw $0xaa55, %bx - jne 1f - shrw %cx /* Bit 0 = fixed disk subset */ - jnc 1f - - /* We have EBIOS; patch in the following code at - read_sector_cbios: movb $0x42, %ah ; jmp read_common */ - movl $0xeb42b4+((read_common-read_sector_cbios-4) << 24), \ - (read_sector_cbios) - -1: - popw %dx - - /* Get (C)HS geometry */ - movb $0x08, %ah - int $0x13 - andw $0x3f, %cx /* Sector count */ - pushw %cx /* Save sectors on the stack */ - movzbw %dh, %ax /* dh = max head */ - incw %ax /* From 0-based max to count */ - mulw %cx /* Heads*sectors -> sectors per cylinder */ - - /* Save sectors/cylinder on the stack */ - pushw %dx /* High word */ - pushw %ax /* Low word */ - - xorl %eax, %eax /* Base */ - cdq /* Root (%edx <- 0) */ - call scan_partition_table - - /* If we get here, we have no OS */ -missing_os: - call error - .ascii "Missing operating system.\r\n" - -/* - * read_sector: read a single sector pointed to by %eax to 0x7c00. - * CF is set on error. All registers saved. - */ -read_sector: - pushal - xorl %edx, %edx - movw $bootsec, %bx - pushl %edx /* MSW of LBA */ - pushl %eax /* LSW of LBA */ - pushw %es /* Buffer segment */ - pushw %bx /* Buffer offset */ - pushw $1 /* Sector count */ - pushw $16 /* Size of packet */ - movw %sp, %si - - /* This chunk is skipped if we have ebios */ - /* Do not clobber %eax before this chunk! */ - /* This also relies on %bx and %edx as set up above. */ -read_sector_cbios: - divl (secpercyl) - shlb $6, %ah - movb %ah, %cl - movb %al, %ch - xchgw %dx, %ax - divb (sectors) - movb %al, %dh - orb %ah, %cl - incw %cx /* Sectors are 1-based */ - movw $0x0201, %ax - -read_common: - movb (driveno), %dl - int $0x13 - leaw 16(%si), %sp /* Drop DAPA */ - popal - ret - -/* - * read_partition_table: - * Read a partition table (pointed to by %eax), and copy - * the partition table into the ptab buffer. - * - * Clobbers %si, %di, and %cx, other registers preserved. - * %cx = 0 on exit. - * - * On error, CF is set and ptab is overwritten with junk. - */ -ptab = _start+446 - -read_partition_table: - call read_sector - movw $bootsec+446, %si - movw $ptab, %di - movw $(16*4/2), %cx - rep ; movsw - ret - -/* - * scan_partition_table: - * Scan a partition table currently loaded in the partition table - * area. Preserve all registers. - * - * On entry: - * %eax - base (location of this partition table) - * %edx - root (offset from MBR, or 0 for MBR) - * - * These get pushed into stack slots: - * 28(%bp) - %eax - base - * 20(%bp) - %edx - root - */ - -scan_partition_table: - pushal - movw %sp, %bp - - /* Search for active partitions */ - movw $ptab, %bx - movw $4, %cx - xorw %ax, %ax - push %bx - push %cx -5: - testb $0x80, (%bx) - jz 6f - incw %ax - movw %bx, %si -6: - addw $16, %bx - loopw 5b - - decw %ax /* Number of active partitions found */ - jz boot - jns too_many_active - - /* No active partitions found, look for extended partitions */ - popw %cx /* %cx <- 4 */ - popw %bx /* %bx <- ptab */ -7: - movb 4(%bx), %al - cmpb $0x0f, %al /* 0x0f = Win9x extended */ - je 8f - andb $~0x80, %al /* 0x85 = Linux extended */ - cmpb $0x05, %al /* 0x05 = MS-DOS extended */ - jne 9f - - /* It is an extended partition. Read the extended partition and - try to scan it. If the scan returns, re-load the current - partition table and resume scan. */ -8: - movl 8(%bx), %eax /* Partition table offset */ - movl 20(%bp), %edx /* "Root" */ - addl %edx, %eax /* Compute location of new ptab */ - andl %edx, %edx /* Is this the MBR? */ - jnz 10f - movl %eax, %edx /* Offset -> root if this was MBR */ -10: - call read_partition_table - jc 11f - call scan_partition_table -11: - /* This returned, so we need to reload the current partition table */ - movl 28(%bp), %eax /* "Base" */ - call read_partition_table - - /* fall through */ -9: - /* Not an extended partition */ - addw $16, %bx - loopw 7b - - /* Nothing found, return */ - popal - ret - -too_many_active: - call error - .ascii "Multiple active partitions.\r\n" - -/* - * boot: invoke the actual bootstrap. (%si) points to the partition - * table entry, and 28(%bp) has the partition table base. - */ -boot: - movl 8(%si), %eax - addl 28(%bp), %eax - movl %eax, 8(%si) /* Adjust in-memory partition table entry */ - call read_sector - jc disk_error - cmpw $0xaa55, (bootsec+510) - jne missing_os /* Not a valid boot sector */ - movw $driveno, %sp /* driveno == bootsec-6 */ - popw %dx /* dl -> drive number */ - popw %di /* es:di -> $PnP vector */ - popw %es - cli - jmpw *%sp /* %sp == bootsec */ - -disk_error: - call error - .ascii "Operating system load error.\r\n" - -/* - * Print error messages. This is invoked with "call", with the - * error message at the return address. - */ -error: - popw %si -2: - lodsb - movb $0x0e, %ah - movb (BIOS_page), %bh - movb $0x07, %bl - int $0x10 /* May destroy %bp */ - cmpb $10, %al /* Newline? */ - jne 2b - - int $0x18 /* Boot failure */ -die: - hlt - jmp die |