diff options
Diffstat (limited to 'contrib/syslinux-4.02/mbr/gptmbr.S')
-rw-r--r-- | contrib/syslinux-4.02/mbr/gptmbr.S | 309 |
1 files changed, 309 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/mbr/gptmbr.S b/contrib/syslinux-4.02/mbr/gptmbr.S new file mode 100644 index 0000000..8ed4cf4 --- /dev/null +++ b/contrib/syslinux-4.02/mbr/gptmbr.S @@ -0,0 +1,309 @@ +/* ----------------------------------------------------------------------- + * + * Copyright 2007-2009 H. Peter Anvin - All Rights Reserved + * Copyright 2009-2010 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 + +/* Partition table header here */ +phdr = stack /* Above the stack, overwritten by bootsect */ +/* Partition table sector here */ +/* To handle > 32K we need to play segment tricks... */ +psec = _phdr + 512 + +/* Where we put DS:SI */ +dssi_out = _start + 0x1be + +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 /* 4(%bp) es:di -> $PnP header */ + pushw %di /* 2(%bp) */ + 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 /* 0(%bp) = %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 */ + movw %sp, %bp /* %bp -> frame pointer: LEAVE UNCHANGED */ + pushw %cx /* -2(%bp) 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 /* -4(%bp) High word */ + pushw %ax /* -6(%bp) Low word */ + + /* Load partition table header */ + xorl %eax,%eax + cltd + incw %ax /* %edx:%eax = 1 */ + movw $phdr, %bx + pushw %bx /* -8(%bp) phdr == bootsect */ + call read_sector + + /* Number of partition sectors */ + /* We assume the partition table is 32K or less, and that + the sector size is 512. */ + /* Note: phdr == 6(%bp) */ + movw (80+6)(%bp),%cx /* NumberOfPartitionEntries */ + movw (84+6)(%bp),%ax /* SizeOfPartitionEntry */ + pushw %ax + pushw %cx + mulw %cx + shrw $9,%ax + xchgw %ax,%cx + incw %cx + + /* Starting LBA of partition array */ + movl (72+6)(%bp),%eax + movl (76+6)(%bp),%edx + + pushw %bx +get_ptab: + call read_sector + call inc64 + loopw get_ptab + + /* Find the boot partition */ + xorw %si,%si /* Nothing found yet */ + popw %di /* Partition table in memory */ + popw %cx /* NumberOfPartitionEntries */ + popw %ax /* SizeOfPartitionEntry */ + +find_part: + /* If the PartitionTypeGUID is all zero, it's an empty slot */ + movl (%di),%edx + orl 4(%di),%edx + orl 8(%di),%edx + orl 12(%di),%edx + jz not_this + testb $0x04,48(%di) + jz not_this + andw %si,%si + jnz found_multiple + movw %di,%si +not_this: + addw %ax,%di + loopw find_part + + andw %si,%si + jnz found_part + +missing_os: + call error + .ascii "Missing OS\r\n" + +found_multiple: + call error + .ascii "Multiple active partitions\r\n" + +found_part: + xchgw %ax,%cx /* Set up %cx for rep movsb further down */ + + movw $dssi_out,%di + pushw %di + + /* 80 00 00 00 ee 00 00 00 + - bootable partition, type EFI (EE), no CHS information */ + xorl %eax,%eax + movb $0x80,%al + stosl + movb $0xed,%al + stosl + movl 32(%si),%eax + movl 36(%si),%edx + call saturate_stosl /* Partition start */ + + movl 40(%si),%eax + movl 44(%si),%edx + subl 32(%si),%eax + sbbl 36(%si),%edx + call inc64 + call saturate_stosl /* Partition length */ + + movzwl %cx,%eax /* Length of GPT entry */ + stosl + + rep; movsb /* GPT entry follows MBR entry */ + popw %si + +/* + * boot: invoke the actual bootstrap. %ds:%si points to the + * partition information in memory. The top word on the stack + * is phdr == 0x7c00 == the address of the boot sector. + */ +boot: + movl (32+20)(%si),%eax + movl (36+20)(%si),%edx + popw %bx + call read_sector + cmpw $0xaa55, -2(%bx) + jne missing_os /* Not a valid boot sector */ + movw %bp, %sp /* driveno == bootsec-6 */ + popw %dx /* dl -> drive number */ + popw %di /* es:di -> $PnP vector */ + popw %es + movl $0x54504721,%eax /* !GPT magic number */ + cli + jmpw *%sp /* %sp == bootsec */ + +/* + * Store the value in %eax to %di iff %edx == 0, otherwise store -1. + * Returns the value that was actually written in %eax. + */ +saturate_stosl: + andl %edx,%edx + jz 1f + orl $-1,%eax +1: stosl + ret + +/* + * Increment %edx:%eax + */ +inc64: + addl $1,%eax + adcl $0,%edx + ret + +/* + * read_sector: read a single sector pointed to by %edx:%eax to + * %es:%bx. CF is set on error. All registers saved. + */ +read_sector: + pushal + 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 %es:%bx or %edx:%eax before this chunk! */ +read_sector_cbios: + divl -6(%bp) /* secpercyl */ + shlb $6, %ah + movb %ah, %cl + movb %al, %ch + xchgw %dx, %ax + divb -2(%bp) /* sectors */ + movb %al, %dh + orb %ah, %cl + incw %cx /* Sectors are 1-based */ + movw $0x0201, %ax + +read_common: + movb (%bp), %dl /* driveno */ + int $0x13 + leaw 16(%si), %sp /* Drop DAPA */ + popal + jc disk_error + addb $2, %bh /* bx += 512: point to the next buffer */ + ret + +disk_error: + call error + .ascii "Disk error on boot\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 |