mirror of
https://git.proxmox.com/git/grub2
synced 2025-11-04 10:24:12 +00:00
fb88381212
(LOCAL(firstlist)): ... this. Move it before the firstlist and not after. All users updated.
379 lines
8.5 KiB
ArmAsm
379 lines
8.5 KiB
ArmAsm
/*
|
|
* GRUB -- GRand Unified Bootloader
|
|
* Copyright (C) 1999,2000,2001,2002,2006,2007,2009,2010 Free Software Foundation, Inc.
|
|
*
|
|
* GRUB is free software: you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation, either version 3 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* GRUB is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <grub/symbol.h>
|
|
#include <grub/machine/boot.h>
|
|
|
|
/*
|
|
* defines for the code go here
|
|
*/
|
|
|
|
#define MSG(x) movw $x, %si; call LOCAL(message)
|
|
|
|
.file "diskboot.S"
|
|
|
|
.text
|
|
|
|
/* Tell GAS to generate 16-bit instructions so that this code works
|
|
in real mode. */
|
|
.code16
|
|
|
|
.globl start, _start
|
|
start:
|
|
_start:
|
|
/*
|
|
* _start is loaded at 0x2000 and is jumped to with
|
|
* CS:IP 0:0x2000 in kernel.
|
|
*/
|
|
|
|
/*
|
|
* we continue to use the stack for boot.img and assume that
|
|
* some registers are set to correct values. See boot.S
|
|
* for more information.
|
|
*/
|
|
|
|
/* save drive reference first thing! */
|
|
pushw %dx
|
|
|
|
/* print a notification message on the screen */
|
|
pushw %si
|
|
MSG(notification_string)
|
|
popw %si
|
|
|
|
/* this sets up for the first run through "bootloop" */
|
|
movw $LOCAL(firstlist), %di
|
|
|
|
/* save the sector number of the second sector in %ebp */
|
|
movl (%di), %ebp
|
|
|
|
/* this is the loop for reading the rest of the kernel in */
|
|
LOCAL(bootloop):
|
|
|
|
/* check the number of sectors to read */
|
|
cmpw $0, 8(%di)
|
|
|
|
/* if zero, go to the start function */
|
|
je LOCAL(bootit)
|
|
|
|
LOCAL(setup_sectors):
|
|
/* check if we use LBA or CHS */
|
|
cmpb $0, -1(%si)
|
|
|
|
/* use CHS if zero, LBA otherwise */
|
|
je LOCAL(chs_mode)
|
|
|
|
/* load logical sector start */
|
|
movl (%di), %ebx
|
|
movl 4(%di), %ecx
|
|
|
|
/* the maximum is limited to 0x7f because of Phoenix EDD */
|
|
xorl %eax, %eax
|
|
movb $0x7f, %al
|
|
|
|
/* how many do we really want to read? */
|
|
cmpw %ax, 8(%di) /* compare against total number of sectors */
|
|
|
|
/* which is greater? */
|
|
jg 1f
|
|
|
|
/* if less than, set to total */
|
|
movw 8(%di), %ax
|
|
|
|
1:
|
|
/* subtract from total */
|
|
subw %ax, 8(%di)
|
|
|
|
/* add into logical sector start */
|
|
addl %eax, (%di)
|
|
adcl $0, 4(%di)
|
|
|
|
/* set up disk address packet */
|
|
|
|
/* the size and the reserved byte */
|
|
movw $0x0010, (%si)
|
|
|
|
/* the number of sectors */
|
|
movw %ax, 2(%si)
|
|
|
|
/* the absolute address */
|
|
movl %ebx, 8(%si)
|
|
movl %ecx, 12(%si)
|
|
|
|
/* the segment of buffer address */
|
|
movw $GRUB_BOOT_MACHINE_BUFFER_SEG, 6(%si)
|
|
|
|
/* save %ax from destruction! */
|
|
pushw %ax
|
|
|
|
/* the offset of buffer address */
|
|
movw $0, 4(%si)
|
|
|
|
/*
|
|
* BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory
|
|
* Call with %ah = 0x42
|
|
* %dl = drive number
|
|
* %ds:%si = segment:offset of disk address packet
|
|
* Return:
|
|
* %al = 0x0 on success; err code on failure
|
|
*/
|
|
|
|
movb $0x42, %ah
|
|
int $0x13
|
|
|
|
jc LOCAL(read_error)
|
|
|
|
movw $GRUB_BOOT_MACHINE_BUFFER_SEG, %bx
|
|
jmp LOCAL(copy_buffer)
|
|
|
|
LOCAL(chs_mode):
|
|
/* load logical sector start (top half) */
|
|
movl 4(%di), %eax
|
|
orl %eax, %eax
|
|
jnz LOCAL(geometry_error)
|
|
|
|
/* load logical sector start (bottom half) */
|
|
movl (%di), %eax
|
|
|
|
/* zero %edx */
|
|
xorl %edx, %edx
|
|
|
|
/* divide by number of sectors */
|
|
divl (%si)
|
|
|
|
/* save sector start */
|
|
movb %dl, 10(%si)
|
|
|
|
xorl %edx, %edx /* zero %edx */
|
|
divl 4(%si) /* divide by number of heads */
|
|
|
|
/* save head start */
|
|
movb %dl, 11(%si)
|
|
|
|
/* save cylinder start */
|
|
movw %ax, 12(%si)
|
|
|
|
/* do we need too many cylinders? */
|
|
cmpw 8(%si), %ax
|
|
jge LOCAL(geometry_error)
|
|
|
|
/* determine the maximum sector length of this read */
|
|
movw (%si), %ax /* get number of sectors per track/head */
|
|
|
|
/* subtract sector start */
|
|
subb 10(%si), %al
|
|
|
|
/* how many do we really want to read? */
|
|
cmpw %ax, 8(%di) /* compare against total number of sectors */
|
|
|
|
|
|
/* which is greater? */
|
|
jg 2f
|
|
|
|
/* if less than, set to total */
|
|
movw 8(%di), %ax
|
|
|
|
2:
|
|
/* subtract from total */
|
|
subw %ax, 8(%di)
|
|
|
|
/* add into logical sector start */
|
|
addl %eax, (%di)
|
|
adcl $0, 4(%di)
|
|
|
|
/*
|
|
* This is the loop for taking care of BIOS geometry translation (ugh!)
|
|
*/
|
|
|
|
/* get high bits of cylinder */
|
|
movb 13(%si), %dl
|
|
|
|
shlb $6, %dl /* shift left by 6 bits */
|
|
movb 10(%si), %cl /* get sector */
|
|
|
|
incb %cl /* normalize sector (sectors go
|
|
from 1-N, not 0-(N-1) ) */
|
|
orb %dl, %cl /* composite together */
|
|
movb 12(%si), %ch /* sector+hcyl in cl, cylinder in ch */
|
|
|
|
/* restore %dx */
|
|
popw %dx
|
|
pushw %dx
|
|
|
|
/* head number */
|
|
movb 11(%si), %dh
|
|
|
|
pushw %ax /* save %ax from destruction! */
|
|
|
|
/*
|
|
* BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory
|
|
* Call with %ah = 0x2
|
|
* %al = number of sectors
|
|
* %ch = cylinder
|
|
* %cl = sector (bits 6-7 are high bits of "cylinder")
|
|
* %dh = head
|
|
* %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
|
|
* %es:%bx = segment:offset of buffer
|
|
* Return:
|
|
* %al = 0x0 on success; err code on failure
|
|
*/
|
|
|
|
movw $GRUB_BOOT_MACHINE_BUFFER_SEG, %bx
|
|
movw %bx, %es /* load %es segment with disk buffer */
|
|
|
|
xorw %bx, %bx /* %bx = 0, put it at 0 in the segment */
|
|
movb $0x2, %ah /* function 2 */
|
|
int $0x13
|
|
|
|
jc LOCAL(read_error)
|
|
|
|
/* save source segment */
|
|
movw %es, %bx
|
|
|
|
LOCAL(copy_buffer):
|
|
|
|
/* load addresses for copy from disk buffer to destination */
|
|
movw 10(%di), %es /* load destination segment */
|
|
|
|
/* restore %ax */
|
|
popw %ax
|
|
|
|
/* determine the next possible destination address (presuming
|
|
512 byte sectors!) */
|
|
shlw $5, %ax /* shift %ax five bits to the left */
|
|
addw %ax, 10(%di) /* add the corrected value to the destination
|
|
address for next time */
|
|
|
|
/* save addressing regs */
|
|
pusha
|
|
pushw %ds
|
|
|
|
/* get the copy length */
|
|
shlw $3, %ax
|
|
movw %ax, %cx
|
|
|
|
xorw %di, %di /* zero offset of destination addresses */
|
|
xorw %si, %si /* zero offset of source addresses */
|
|
movw %bx, %ds /* restore the source segment */
|
|
|
|
cld /* sets the copy direction to forward */
|
|
|
|
/* perform copy */
|
|
rep /* sets a repeat */
|
|
movsw /* this runs the actual copy */
|
|
|
|
/* restore addressing regs and print a dot with correct DS
|
|
(MSG modifies SI, which is saved, and unused AX and BX) */
|
|
popw %ds
|
|
MSG(notification_step)
|
|
popa
|
|
|
|
/* check if finished with this dataset */
|
|
cmpw $0, 8(%di)
|
|
jne LOCAL(setup_sectors)
|
|
|
|
/* update position to load from */
|
|
subw $GRUB_BOOT_MACHINE_LIST_SIZE, %di
|
|
|
|
/* jump to bootloop */
|
|
jmp LOCAL(bootloop)
|
|
|
|
/* END OF MAIN LOOP */
|
|
|
|
LOCAL(bootit):
|
|
/* print a newline */
|
|
MSG(notification_done)
|
|
popw %dx /* this makes sure %dl is our "boot" drive */
|
|
ljmp $0, $(GRUB_BOOT_MACHINE_KERNEL_ADDR + 0x200)
|
|
|
|
|
|
/*
|
|
* BIOS Geometry translation error (past the end of the disk geometry!).
|
|
*/
|
|
LOCAL(geometry_error):
|
|
MSG(geometry_error_string)
|
|
jmp LOCAL(general_error)
|
|
|
|
/*
|
|
* Read error on the disk.
|
|
*/
|
|
LOCAL(read_error):
|
|
MSG(read_error_string)
|
|
|
|
LOCAL(general_error):
|
|
MSG(general_error_string)
|
|
|
|
/* go here when you need to stop the machine hard after an error condition */
|
|
LOCAL(stop): jmp LOCAL(stop)
|
|
|
|
notification_string: .asciz "loading"
|
|
|
|
notification_step: .asciz "."
|
|
notification_done: .asciz "\r\n"
|
|
|
|
geometry_error_string: .asciz "Geom"
|
|
read_error_string: .asciz "Read"
|
|
general_error_string: .asciz " Error"
|
|
|
|
/*
|
|
* message: write the string pointed to by %si
|
|
*
|
|
* WARNING: trashes %si, %ax, and %bx
|
|
*/
|
|
|
|
/*
|
|
* Use BIOS "int 10H Function 0Eh" to write character in teletype mode
|
|
* %ah = 0xe %al = character
|
|
* %bh = page %bl = foreground color (graphics modes)
|
|
*/
|
|
1:
|
|
movw $0x0001, %bx
|
|
movb $0xe, %ah
|
|
int $0x10 /* display a byte */
|
|
|
|
incw %si
|
|
LOCAL(message):
|
|
movb (%si), %al
|
|
cmpb $0, %al
|
|
jne 1b /* if not end of string, jmp to display */
|
|
ret
|
|
|
|
/*
|
|
* This area is an empty space between the main body of code below which
|
|
* grows up (fixed after compilation, but between releases it may change
|
|
* in size easily), and the lists of sectors to read, which grows down
|
|
* from a fixed top location.
|
|
*/
|
|
|
|
.word 0
|
|
.word 0
|
|
|
|
. = _start + 0x200 - GRUB_BOOT_MACHINE_LIST_SIZE
|
|
LOCAL(firstlist): /* this label has to be before the first list entry!!! */
|
|
/* fill the first data listing with the default */
|
|
blocklist_default_start:
|
|
/* this is the sector start parameter, in logical sectors from
|
|
the start of the disk, sector 0 */
|
|
.long 2, 0
|
|
blocklist_default_len:
|
|
/* this is the number of sectors to read. grub-mkimage
|
|
will fill this up */
|
|
.word 0
|
|
blocklist_default_seg:
|
|
/* this is the segment of the starting address to load the data into */
|
|
.word (GRUB_BOOT_MACHINE_KERNEL_SEG + 0x20)
|