hdprefix that works for LBA only
This commit is contained in:
Michael Brown
parent
839960276d
commit
66208dd65d
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@ -44,7 +44,7 @@ find_active_partition:
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jc 1f
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cmpw $0xaa55, %bx
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jne 1f
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movw $read_lba, read_sector
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movw $read_lba, read_sectors
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1:
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/* Read and process root partition table */
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xorb %dh, %dh
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@ -55,17 +55,26 @@ find_active_partition:
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/* Print failure message */
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movw $10f, %si
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movw $(20f-10f), %cx
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1: movw $0x0007, %bx
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movb $0x0e, %ah
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lodsb
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int $0x10
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loop 1b
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jmp boot_error
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10: .asciz "Could not locate active partition\r\n"
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/* Boot next device */
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/*
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* Print failure message and boot next device
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*
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* Parameters:
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* %si : Failure string
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*/
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boot_error:
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cld
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movw $0x0007, %bx
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movb $0x0e, %ah
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1: lodsb
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testb %al, %al
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je 99f
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int $0x10
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jmp 1b
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99: /* Boot next device */
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int $0x18
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10: .ascii "Could not locate active partition\r\n"
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20:
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/*
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* Process partition table
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@ -149,7 +158,7 @@ process_partition:
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read_boot_sector:
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pushw %ax
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movw $1, %ax
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call *read_sector
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call *read_sectors
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jc 99f
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cmpw $0xaa55, %es:(510)
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je 99f
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@ -158,7 +167,7 @@ read_boot_sector:
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ret
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/*
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* Read single sector to %es:0000 and verify 0x55aa signature
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* Read sectors to %es:0000
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*
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* Parameters:
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* %dl : BIOS drive number
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@ -171,7 +180,7 @@ read_boot_sector:
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* Returns:
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* CF set on error
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*/
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read_sector: .word read_chs
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read_sectors: .word read_chs
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read_chs:
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/* Read sectors using C/H/S address */
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@ -1,301 +1,63 @@
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#warning "Needs fixing up for gpxe"
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#if 0
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/****************************************************************\
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hdprefix.S Copyright (C) 2005 Per Dalgas Jakobsen
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This code has been inspired/derived by the OSLoader by Vladislav Aleksandrov.
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http://www.programmersheaven.com/zone5/cat469/40546.htm.
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This software may be used and distributed according to the terms
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of the GNU Public License (GPL), incorporated herein by reference.
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hdprefix.S is loaded at 0x0000:0x7c00 by the bios-startup routines.
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Actions performed by hdprefix:
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1) Load the MBR to LOADSEG:0
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2) Check which partition is active (or try first partition if none active)
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3) Check wether LBA is supported.
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3a) LBA
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3a1) Load PAYLOAD_SECTS sectors from chosen partition to LOADSEG:0
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3b) CHS (standard)
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3b1) Load PAYLOAD_SECTS sectors from chosen partition to LOADSEG:0
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4) Check loaded bootsector for BOOTMAGIC code.
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5) Jump to payload LOADSEG:ENTRYPOINT.
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Output with failure points (!#):
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---
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Loading (!1)partition #
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Std. BIOS(!2) | Ext. BIOS(!3)
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Booting...(!4)
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(!5)
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---
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!1: Failed to load MBR with Int13,ah=2.
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!2: Failed to load bootrecord+payload with Int13,ah=2.
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!3: Failed to load bootrecord+payload with Int13,ah=42.
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!4: Invalid BOOTMAGIC in loaded bootrecord.
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!5: Jumping to payload.
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\*****************************************************************/
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.equ BOOTSEG, 0x07c0
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.equ LOADSEG, 0x1000
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.equ ENTRYPOINT, _start
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.equ BOOTMAGIC, 0x0aa55
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.equ partition_table, 0x1be
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.equ partition_rec_size, 0x10
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.equ boot_ind, 0 /* 80h=active */
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.equ start_head, 1
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.equ start_sector, 2 /* bits 0-5 */
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.equ start_cyl, 3 /* bits 8,9 in bits 6,7 of sector */
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.equ os_ind, 4 /* os indicator */
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.equ end_head, 5
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.equ end_sector, 6 /* bits 0-5 */
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.equ end_track, 7 /* bits 8,9 in bits 6,7 of sector */
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.equ nsect, 8 /* sectors preceding partition */
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.equ lenght, 0x0c /* length of partition in sectors */
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/-------------------------------------------------------------
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.arch i386
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.text
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.section ".prefix", "ax", @progbits
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.arch i386
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.section ".prefix", "awx", @progbits
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.code16
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bootstart:
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jmp $BOOTSEG,$_go /* reload cs:ip */
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.org 0
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movw $load_image, %bp
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jmp find_active_partition
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/****************************************************************/
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/* support routines. */
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/*--------------------------------------------------------------*/
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_failed:
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movw $BOOTSEG,%ax
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movw %ax,%ds
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movw $_failed_msg_end-_failed_msg,%cx
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movw $_failed_msg,%si
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call _print_str
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#include "bootpart.S"
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/* stop execution - should probably have option to auto-reboot after delay. */
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_failed_loop:
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jmp _failed_loop
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load_image:
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movw $_rom_size, %bp
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1: /* Truncate read length to end of track */
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movzwl %bp, %eax
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movw $1, %ax
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/* Read sectors */
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call *read_sectors
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jc load_failed
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/* Update %es */
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movw %es, %bx
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shll $5, %eax
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addw %ax, %bx
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movw %bx, %es
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shrl $5, %eax
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/* Update LBA address */
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addl %eax, %edi
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adcl $0, %esi
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/* Update CHS address */
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// hmmmm
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/* Loop until whole image is read */
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subw %ax, %bp
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jne 1b
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ljmp $BOOT_SEG, $start_image
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/*--------------------------------------------------------------*/
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_print_str:
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/* cx = count, ds:si = string. */
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movw $0x0007,%bx
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movb $0x0e,%ah
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_print_loop:
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lodsb
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int $0x10
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loop _print_loop
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ret
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load_failed:
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movw $10f, %si
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jmp boot_error
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10: .asciz "Could not load gPXE\r\n"
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/*--------------------------------------------------------------*/
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_print_char:
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/* al = char. */
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movw $0x0007,%bx
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movb $0x0e,%ah
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int $0x10
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ret
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.org 510
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.byte 0x55, 0xaa
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/*--------------------------------------------------------------*/
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_print_nl:
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/* - */
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movb $0x0d,%al
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call _print_char
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movb $0x0a,%al
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call _print_char
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ret
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start_image:
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call install
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/*--------------------------------------------------------------*/
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_print_hex:
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/* dx = value */
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movb $0x0e,%ah /* write char, tty mode */
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movw $0x0007,%bx /* page 0, attribute 7 (normal) */
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call _print_digit
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call _print_digit
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call _print_digit
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/* fall through */
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_print_digit:
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rolw $4,%dx /* rotate so that lowest 4 bits are used */
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movb $0x0f,%al /* mask for nibble */
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andb %dl,%al
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addb $0x90,%al /* convert al to ascii hex (four instructions) */
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daa
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adcb $0x40,%al
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daa
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int $0x10
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ret
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/* Set up real-mode stack */
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movw %bx, %ss
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movw $_estack16, %sp
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/****************************************************************/
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/* Jump to .text16 segment */
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pushw %ax
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pushw $1f
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lret
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.section ".text16", "awx", @progbits
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1:
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pushl $main
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pushw %cs
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call prot_call
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popl %eax /* discard */
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_go:
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cli
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movw $BOOTSEG,%ax
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movw %ax,%ds
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movw %ax,%ss
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movw $0x2000,%sp /* good large stack. */
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sti
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cld
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movw $LOADSEG,%ax
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movw %ax,%es
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movw $_load_msg_end-_load_msg,%cx
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movw $_load_msg,%si
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call _print_str
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/*--- load MBR so we can use its partition table. ---*/
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xorw %bx,%bx
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movw $0x0001,%cx /* chs: 0,0,1 */
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movb %bh,%dh /* - */
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movb $0x80,%dl
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movw $0x0201,%ax /* read one sector (MBR) */
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int $0x13
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jc _failed
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/*--- find the active partition ---*/
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movw $_part_msg_end-_part_msg,%cx
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movw $_part_msg,%si
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call _print_str
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movw $partition_table,%di
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movw $4,%cx
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_partition_loop:
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cmpb $0x80,%es:(%di) /* active? */
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je _partition_found
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addw $partition_rec_size,%di
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loop _partition_loop
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/*- no partitions marked active - use 1. partition. */
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movw $partition_table,%di
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movw $4,%cx
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_partition_found:
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movb $'5',%al /* convert to ascii */
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subb %cl,%al
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call _print_char
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call _print_nl
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/*--- check for lba support ---*/
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movw $0x55aa,%bx
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movb $0x80,%dl
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movb $0x41,%ah
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int $0x13
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jc __bios
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cmpw $0x0aa55,%bx
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jnz __bios
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testb $1,%cl
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jz __bios
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/*--- use lba bios calls to read sectors ---*/
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_lba:
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movw $_extbios_msg_end-_extbios_msg,%cx
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movw $_extbios_msg,%si
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call _print_str
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movw %es:nsect(%di),%ax
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movw %ax,_bios_lba_low
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movw %es:nsect+2(%di),%ax
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movw %ax,_bios_lba_high
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movb $0x80,%dl
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movw $_disk_address_packet,%si
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movw $0x4200,%ax /* read */
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int $0x13
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jc _failed
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jmp __loaded
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/*--- use standard bios calls to read sectors ---*/
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__bios:
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movw $_stdbios_msg_end-_stdbios_msg,%cx
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movw $_stdbios_msg,%si
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call _print_str
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movw _disk_address_packet+2(,1),%ax /* only low byte is used. */
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xorw %bx,%bx
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movw %es:start_sector(%di),%cx
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movb %es:start_head(%di),%dh
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movb $0x80,%dl
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movb $0x02,%ah
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int $0x13
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jc _failed
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__loaded:
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movw $_boot_msg_end-_boot_msg,%cx
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movw $_boot_msg,%si
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call _print_str
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/* check if it has a valid bootrecord. */
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cmpw $BOOTMAGIC,%es:510(,1)
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jne _failed
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call _print_nl
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/* call the payload. */
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pushl $0 /* No parameters to preserve for exit path */
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pushw $0 /* Use prefix exit path mechanism */
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jmp $LOADSEG,$ENTRYPOINT
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.section ".text16", "ax", @progbits
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.globl prefix_exit
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prefix_exit:
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int $0x19 /* should try to boot machine */
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.globl prefix_exit_end
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prefix_exit_end:
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.previous
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/*--------------------------------------------------------------*/
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_load_msg: .ascii "Loading "
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_load_msg_end:
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_part_msg: .ascii "partition "
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_part_msg_end:
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_boot_msg: .ascii "Booting..."
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_boot_msg_end:
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_stdbios_msg: .ascii "Std. BIOS\r\n"
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_stdbios_msg_end:
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_extbios_msg: .ascii "Ext. BIOS\r\n"
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_extbios_msg_end:
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_failed_msg: .ascii "FAILED!!!\r\n"
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_failed_msg_end:
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/*--------------------------------------------------------------*/
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_disk_address_packet:
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.byte 0x10 /* size of the packet */
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.byte 0 /* reserved */
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.word _verbatim_size_sct /* number of sectors to read */
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.word 0x0000 /* offset */
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.word LOADSEG /* segment of buffer */
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_bios_lba_low: .word 0
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_bios_lba_high: .word 0
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.word 0
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.word 0
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.rept 32
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.byte 0
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.endr
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/*--- Partition table ------------------------------------------*/
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.org 446, 0
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.rept 64
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.byte 0
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.endr
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/*--- Magic code -----------------------------------------------*/
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.org 510, 0
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.word BOOTMAGIC
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/*** END ********************************************************/
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#endif
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/* Boot next device */
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int $0x18
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