mirror of
https://gitlab.com/bztsrc/bootboot.git
synced 2023-02-13 20:54:32 -05:00
Removed int13/AX=4B01 as it's buggy on some BIOSes
This commit is contained in:
bzt
parent
0cab242a9d
commit
dd0d222cc4
5 changed files with 55 additions and 54 deletions
BIN
dist/boot.bin
vendored
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dist/boot.bin
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dist/bootboot.bin
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dist/bootboot.bin
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@ -33,6 +33,7 @@
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;*********************************************************************
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;LBA packet fields
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lba_packet equ 07E00h
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virtual at lba_packet
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lbapacket.size: dw ?
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lbapacket.count:dw ?
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@ -72,10 +73,9 @@ end if
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bootboot_record:
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jmp short .skipid
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nop
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.system: db "BOOTBOOT",0
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;skip BPB area so that we can use this
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;boot code on a FAT volume if needed
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db 05Ah-($-$$) dup 0
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;boot code on a FAT / exFAT volume if needed
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db 120-($-$$) dup 0
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.skipid: ;relocate our code to offset 0h:600h
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cli
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cld
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@ -105,9 +105,6 @@ bootboot_record:
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.start: ;save boot drive code
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mov byte [drive], dl
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;initialize lba packet
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mov byte [lbapacket.size], 16
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mov byte [lbapacket.addr0+1], 08h ;to address 800h
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;check for lba presistance - floppy not supported any more
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;we use USB sticks as removable media for a long time
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cmp dl, byte 80h
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@ -125,27 +122,23 @@ bootboot_record:
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jmp diefunc
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.lbaok: ;try to load stage2 - it's a continous area on disk
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;started at given sector with maximum size of 7000h bytes
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mov di, lba_packet
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mov cx, 8
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xor ax, ax
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repnz stosw
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mov si, stage2_addr
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mov di, lbapacket.sect0
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push bx
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push di
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;set up for hard-drive
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movsw
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movsw
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mov byte [lbapacket.size], 16
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mov byte [lbapacket.addr0+1], 08h ;to address 800h
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mov byte [lbapacket.count], 56
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;query cdrom status to see if it's a cdrom
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mov ax, word 4B01h
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mov dl, byte [drive]
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mov si, spc_packet
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mov byte [si], 13h
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mov byte [si+2], 0h ;clear drive number
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clc
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int 13h
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pop di
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jc @f
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;some buggy BIOSes (like bochs') fail to set carry flag and ax properly
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cmp byte [spc_packet+2], 0h
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jz @f
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;if it's a CDROM with 2048 byte sectors
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cmp dl, 0E0h
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jl @f
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sub di, 4
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;lba=lba/4
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clc
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rcr word [di+2], 1
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@ -153,28 +146,33 @@ bootboot_record:
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clc
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rcr word [di+2], 1
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rcr word [di], 1
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mov byte [lbapacket.count], 14
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shr word [lbapacket.count], 2
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;load sectors
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@@: mov ah, byte 42h
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mov dl, byte [drive]
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mov si, lba_packet
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int 13h
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pop bx
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;do we have a 2nd stage loader?
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.chk: cmp word [ldr.header], bx
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.chk: cmp word [ldr.header], 0AA55h
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jne .nostage2
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cmp byte [ldr.header+3], 0E9h
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jne .nostage2
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mov dl, byte [drive]
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;invoke stage2 real mode code
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mov ax, [ldr.executor]
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add ax, ldr.executor+3
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jmp ax
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.nostage2: ;try to load stage2 from a RAID mirror
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inc byte [drive]
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cmp byte [drive], 8Fh
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jle .lbaok
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mov al, byte [drive]
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inc al
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cmp al, 87h
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jle @f
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mov al, 80h
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@@: mov byte [drive], al
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inc byte [cnt]
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cmp byte [cnt], 8
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jl .lbaok
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.nostage2err:
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mov si, stage2notf
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;fall into the diefunc code
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@ -184,7 +182,6 @@ bootboot_record:
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;*********************************************************************
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;writes the reason, waits for a key and reboots.
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diefunc:
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print bootboot_record.system
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print panic
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call printfunc
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mov si, found
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@ -211,13 +208,12 @@ printfunc:
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;* data area *
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;*********************************************************************
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panic: db "-PANIC: ",0
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panic: db "BOOTBOOT-PANIC: ",0
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lbanotf: db "LBA support",0
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stage2notf: db "FS0:\BOOTBOOT\LOADER",0
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found: db " not found",10,13,0
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found: db " not found",0
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cnt: db 0
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drive: db 0
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lba_packet: db 16 dup 0
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spc_packet: db 13h dup 0
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db 01B0h-($-$$) dup 0
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;right before the partition table some data
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@ -804,6 +804,8 @@ real_diefunc:
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real_print panic
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pop si
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call real_printfunc
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mov si, crlf
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call real_printfunc
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call real_getchar
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mov al, 0FEh
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out 64h, al
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@ -908,23 +910,17 @@ prot_readsectorfunc:
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;load 8 sectors (1 page) or more in low memory
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mov dword [lbapacket.sect0], eax
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prot_realmode
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;try all drives from bootdev-8F to support RAID mirror
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;try all drives from bootdev-87 to support RAID mirror
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mov dl, byte [bootdev]
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mov byte [readdev], dl
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mov byte [cntdev], 0
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mov byte [iscdrom], 0
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.again: mov ax, word [lbapacket.count]
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mov word [origcount], ax
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;query cdrom status to see if it's a cdrom
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mov ax, word 4B01h
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mov dl, byte [readdev]
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mov esi, spc_packet
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mov byte [si], 13h
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mov byte [si+2], 0h ;clear drive number
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clc
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int 13h
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jc @f
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;some buggy BIOSes (like bochs') fail to set carry flag and ax properly
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cmp byte [spc_packet+2], 0h
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jz @f
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;don't use INT 13h / AX=4B01h, that's buggy on many BIOSes
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cmp dl, 0E0h
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jl @f
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;use 2048 byte sectors instead of 512 if it's a cdrom
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mov al, byte [lbapacket.sect0]
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and al, 011b
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@ -932,7 +928,7 @@ prot_readsectorfunc:
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jz .cdok
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;this should never happen.
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; - GPT is loaded from PMBR, from LBA 0 (%4==0)
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; - ESP is at LBA 128 (%4==0)
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; - ESP is at LBA 128 or 2048 (%4==0)
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; - root dir is at LBA 172 (%4==0) for FAT16, and it's cluster aligned for FAT32
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; - cluster size is multiple of 4 sectors
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mov si, notcdsect
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@ -941,16 +937,23 @@ prot_readsectorfunc:
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add word [lbapacket.count], 3
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shr word [lbapacket.count], 2
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mov byte [iscdrom], 1
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@@: mov dl, byte [readdev]
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inc byte [readdev]
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mov ah, byte 42h
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@@: mov ah, byte 42h
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mov esi, lbapacket
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clc
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int 13h
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jnc @f
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cmp byte [readdev], 08Fh
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jnc .rdok
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;we do not expect this to fail, but if so, load sector from another
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;drive assuming we have a RAID mirror. This will fail for non-RAIDs
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mov al, byte [readdev]
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inc al
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cmp al, 87h
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jle @f
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mov al, 80h
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@@: mov byte [readdev], al
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inc byte [cntdev]
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cmp byte [cntdev], 8
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jle .again
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@@: xor ebx, ebx
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.rdok: xor ebx, ebx
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mov bl, ah
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real_protmode
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pop edi
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@ -2662,6 +2665,7 @@ clu_sec: dd 0 ;sector per cluster
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origcount: dw 0
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bootdev: db 0
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readdev: db 0
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cntdev: db 0
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hasinitrd: db 0
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hasconfig: db 0
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iscdrom: db 0
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@ -2690,7 +2694,8 @@ backup: db " * Backup initrd",10,13,0
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passphrase: db " * Passphrase? ",0
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decrypting: db 13," * Decrypting...",0
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clrdecrypt: db 13," ",13,0
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starting: db "Booting OS...",10,13,0
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starting: db "Booting OS..."
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crlf: db 10,13,0
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panic: db "-PANIC: ",0
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noarch: db "Hardware not supported",0
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a20err: db "Failed to enable A20",0
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