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Diffstat (limited to 'contrib/syslinux/latest/core/diskstart.inc')
| -rw-r--r-- | contrib/syslinux/latest/core/diskstart.inc | 883 |
1 files changed, 0 insertions, 883 deletions
diff --git a/contrib/syslinux/latest/core/diskstart.inc b/contrib/syslinux/latest/core/diskstart.inc deleted file mode 100644 index c0301d4..0000000 --- a/contrib/syslinux/latest/core/diskstart.inc +++ /dev/null @@ -1,883 +0,0 @@ -; ----------------------------------------------------------------------- -; -; Copyright 1994-2009 H. Peter Anvin - All Rights Reserved -; Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin -; -; This program 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, Inc., 51 Franklin St, Fifth Floor, -; Boston MA 02110-1301, USA; either version 2 of the License, or -; (at your option) any later version; incorporated herein by reference. -; -; ----------------------------------------------------------------------- - -; -; diskstart.inc -; -; Common early-bootstrap code for harddisk-based Syslinux derivatives. -; - - section .init -; -; Some of the things that have to be saved very early are saved -; "close" to the initial stack pointer offset, in order to -; reduce the code size... -; - -StackBuf equ STACK_TOP-44-92 ; Start the stack here (grow down - 4K) -PartInfo equ StackBuf -.mbr equ PartInfo -.gptlen equ PartInfo+16 -.gpt equ PartInfo+20 -FloppyTable equ PartInfo+76 -; Total size of PartInfo + FloppyTable == 76+16 = 92 bytes -Hidden equ StackBuf-24 ; Partition offset (qword) -OrigFDCTabPtr equ StackBuf-16 ; Original FDC table -OrigDSSI equ StackBuf-12 ; DS:SI -> partinfo -OrigESDI equ StackBuf-8 ; ES:DI -> $PnP structure -DriveNumber equ StackBuf-4 ; Drive number -StackHome equ Hidden ; The start of the canonical stack - -; -; Primary entry point. Tempting as though it may be, we can't put the -; initial "cli" here; the jmp opcode in the first byte is part of the -; "magic number" (using the term very loosely) for the DOS superblock. -; -bootsec equ $ -_start: jmp short start ; 2 bytes - nop ; 1 byte -; -; "Superblock" follows -- it's in the boot sector, so it's already -; loaded and ready for us -; -bsOemName db MY_NAME ; The SYS command sets this, so... - zb 8-($-bsOemName) - -; -; These are the fields we actually care about. We end up expanding them -; all to dword size early in the code, so generate labels for both -; the expanded and unexpanded versions. -; -%macro superb 1 -bx %+ %1 equ SuperInfo+($-superblock)*8+4 -bs %+ %1 equ $ - zb 1 -%endmacro -%macro superw 1 -bx %+ %1 equ SuperInfo+($-superblock)*8 -bs %+ %1 equ $ - zw 1 -%endmacro -%macro superd 1 -bx %+ %1 equ $ ; no expansion for dwords -bs %+ %1 equ $ - zd 1 -%endmacro -superblock equ $ - superw BytesPerSec - superb SecPerClust - superw ResSectors - superb FATs - superw RootDirEnts - superw Sectors - superb Media - superw FATsecs - superw SecPerTrack - superw Heads -superinfo_size equ ($-superblock)-1 ; How much to expand - superd Hidden - superd HugeSectors - ; - ; This is as far as FAT12/16 and FAT32 are consistent - ; - ; FAT12/16 need 26 more bytes, - ; FAT32 need 54 more bytes - ; -superblock_len_fat16 equ $-superblock+26 -superblock_len_fat32 equ $-superblock+54 - zb 54 ; Maximum needed size -superblock_max equ $-superblock - - global SecPerClust -SecPerClust equ bxSecPerClust - -; -; Note we don't check the constraints above now; we did that at install -; time (we hope!) -; -start: - cli ; No interrupts yet, please - cld ; Copy upwards -; -; Set up the stack -; - xor cx,cx - mov ss,cx - mov sp,StackBuf-2 ; Just below BSS (-2 for alignment) - push dx ; Save drive number (in DL) - push es ; Save initial ES:DI -> $PnP pointer - push di - push ds ; Save original DS:SI -> partinfo - push si - mov es,cx - -; -; DS:SI may contain a partition table entry and possibly a GPT entry. -; Preserve it for us. This saves 56 bytes of the GPT entry, which is -; currently the maximum we care about. Total is 76 bytes. -; - mov cl,(16+4+56)/2 ; Save partition info - mov di,PartInfo - rep movsw ; This puts CX back to zero - - mov ds,cx ; Now we can initialize DS... - -; -; Now sautee the BIOS floppy info block to that it will support decent- -; size transfers; the floppy block is 11 bytes and is stored in the -; INT 1Eh vector (brilliant waste of resources, eh?) -; -; Of course, if BIOSes had been properly programmed, we wouldn't have -; had to waste precious space with this code. -; - mov bx,fdctab - lfs si,[bx] ; FS:SI -> original fdctab - push fs ; Save on stack in case we need to bail - push si - - ; Save the old fdctab even if hard disk so the stack layout - ; is the same. The instructions above do not change the flags - and dl,dl ; If floppy disk (00-7F), assume no - ; partition table - js harddisk - -floppy: - xor ax,ax - mov cl,6 ; 12 bytes (CX == 0) - ; es:di -> FloppyTable already - ; This should be safe to do now, interrupts are off... - mov [bx],di ; FloppyTable - mov [bx+2],ax ; Segment 0 - fs rep movsw ; Faster to move words - mov cl,[bsSecPerTrack] ; Patch the sector count - mov [di-76+8],cl - - push ax ; Partition offset == 0 - push ax - push ax - push ax - - int 13h ; Some BIOSes need this - jmp short not_harddisk -; -; The drive number and possibly partition information was passed to us -; by the BIOS or previous boot loader (MBR). Current "best practice" is to -; trust that rather than what the superblock contains. -; -; Note: di points to beyond the end of PartInfo -; -harddisk: - mov dx,[di-76-10] ; Original DS - mov si,[di-76-12] ; Original SI - shr si,4 - add dx,si - cmp dx,PartInfo >> 4 - jae .no_partition - test byte [di-76],7Fh ; Sanity check: "active flag" should - jnz .no_partition ; be 00 or 80 - cmp [di-76+4],cl ; Sanity check: partition type != 0 - je .no_partition - cmp eax,'!GPT' ; !GPT signature? - jne .mbr - cmp byte [di-76+4],0EDh ; Synthetic GPT partition entry? - jne .mbr -.gpt: ; GPT-style partition info - push dword [di-76+20+36] - push dword [di-76+20+32] - jmp .gotoffs -.mbr: ; MBR-style partition info - push cx ; Upper half partition offset == 0 - push cx - push dword [di-76+8] ; Partition offset (dword) - jmp .gotoffs -.no_partition: -; -; No partition table given... assume that the Hidden field in the boot sector -; tells the truth (in particular, is zero if this is an unpartitioned disk.) -; - push cx - push cx - push dword [bsHidden] -.gotoffs: -; -; Get disk drive parameters (don't trust the superblock.) Don't do this for -; floppy drives -- INT 13:08 on floppy drives will (may?) return info about -; what the *drive* supports, not about the *media*. Fortunately floppy disks -; tend to have a fixed, well-defined geometry which is stored in the superblock. -; - ; DL == drive # still - mov ah,08h - int 13h - jc no_driveparm - and ah,ah - jnz no_driveparm - shr dx,8 - inc dx ; Contains # of heads - 1 - mov [bsHeads],dx - and cx,3fh - mov [bsSecPerTrack],cx -no_driveparm: -not_harddisk: -; -; Ready to enable interrupts, captain -; - sti - -; -; Do we have EBIOS (EDD)? -; -eddcheck: - mov bx,55AAh - mov ah,41h ; EDD existence query - mov dl,[DriveNumber] - int 13h - jc .noedd - cmp bx,0AA55h - jne .noedd - test cl,1 ; Extended disk access functionality set - jz .noedd - ; - ; We have EDD support... - ; - mov byte [getonesec.jmp+1],(getonesec_ebios-(getonesec.jmp+2)) -.noedd: - -; -; Load the first sector of LDLINUX.SYS; this used to be all proper -; with parsing the superblock and root directory; it doesn't fit -; together with EBIOS support, unfortunately. -; - mov eax,strict dword 0xdeadbeef -Sect1Ptr0 equ $-4 - mov edx,strict dword 0xfeedface -Sect1Ptr1 equ $-4 - mov bx,ldlinux_sys ; Where to load it - call getonesec - - ; Some modicum of integrity checking - cmp dword [ldlinux_magic+4],LDLINUX_MAGIC^HEXDATE - jne kaboom - - ; Go for it... - jmp 0:ldlinux_ent - - -; -; getonesec: load a single disk linear sector EDX:EAX into the buffer -; at ES:BX. -; -; This routine assumes CS == DS == SS, and trashes most registers. -; -; Stylistic note: use "xchg" instead of "mov" when the source is a register -; that is dead from that point; this saves space. However, please keep -; the order to dst,src to keep things sane. -; -getonesec: - add eax,[Hidden] ; Add partition offset - adc edx,[Hidden+4] - mov cx,retry_count -.jmp: jmp strict short getonesec_cbios - -; -; getonesec_ebios: -; -; getonesec implementation for EBIOS (EDD) -; -getonesec_ebios: -.retry: - ; Form DAPA on stack - push edx - push eax - push es - push bx - push word 1 - push word 16 - mov si,sp - pushad - mov ah,42h ; Extended Read - call xint13 - popad - lea sp,[si+16] ; Remove DAPA - jc .error - ret - -.error: - ; Some systems seem to get "stuck" in an error state when - ; using EBIOS. Doesn't happen when using CBIOS, which is - ; good, since some other systems get timeout failures - ; waiting for the floppy disk to spin up. - - pushad ; Try resetting the device - xor ax,ax - call xint13 - popad - loop .retry ; CX-- and jump if not zero - - ; Total failure. Try falling back to CBIOS. - mov byte [getonesec.jmp+1],(getonesec_cbios-(getonesec.jmp+2)) - -; -; getonesec_cbios: -; -; getlinsec implementation for legacy CBIOS -; -getonesec_cbios: -.retry: - pushad - - movzx esi,word [bsSecPerTrack] - movzx edi,word [bsHeads] - ; - ; Dividing by sectors to get (track,sector): we may have - ; up to 2^18 tracks, so we need to use 32-bit arithmetric. - ; - div esi - xor cx,cx - xchg cx,dx ; CX <- sector index (0-based) - ; EDX <- 0 - ; eax = track # - div edi ; Convert track to head/cyl - - cmp eax,1023 ; Outside the CHS range? - ja kaboom - - ; - ; Now we have AX = cyl, DX = head, CX = sector (0-based), - ; SI = bsSecPerTrack, ES:BX = data target - ; - shl ah,6 ; Because IBM was STOOPID - ; and thought 8 bits were enough - ; then thought 10 bits were enough... - inc cx ; Sector numbers are 1-based, sigh - or cl,ah - mov ch,al - mov dh,dl - mov ax,0201h ; Read one sector - call xint13 - popad - jc .error - ret - -.error: - loop .retry - ; Fall through to disk_error - -; -; kaboom: write a message and bail out. -; - global kaboom -disk_error: -kaboom: - xor si,si - mov ss,si - mov sp,OrigFDCTabPtr ; Reset stack - mov ds,si ; Reset data segment - pop dword [fdctab] ; Restore FDC table -.patch: ; When we have full code, intercept here - mov si,bailmsg - call writestr_early - - xor ax,ax -.again: int 16h ; Wait for keypress - ; NB: replaced by int 18h if - ; chosen at install time.. - int 19h ; And try once more to boot... -.norge: hlt ; If int 19h returned; this is the end - jmp short .norge - -; -; -; writestr_early: write a null-terminated string to the console -; This assumes we're on page 0. This is only used for early -; messages, so it should be OK. -; -writestr_early: - pushad -.loop: lodsb - and al,al - jz .return - mov ah,0Eh ; Write to screen as TTY - mov bx,0007h ; Attribute - int 10h - jmp short .loop -.return: popad - ret - -; -; INT 13h wrapper function -; -xint13: - mov dl,[DriveNumber] - int 13h - ret - -; -; Error message on failure -; -bailmsg: db 'Boot error', 0Dh, 0Ah, 0 - - ; This fails if the boot sector overflowsg - zb 1FEh-($-$$) - -bootsignature dw 0xAA55 - -; -; =========================================================================== -; End of boot sector -; =========================================================================== -; Start of LDLINUX.SYS -; =========================================================================== - -LDLINUX_SYS equ ($-$$)+TEXT_START -ldlinux_sys: - -syslinux_banner db CR, LF, MY_NAME, ' ', VERSION_STR, ' ', DATE_STR, ' ', 0 - db CR, LF, 1Ah ; EOF if we "type" this in DOS - - alignz 8 -ldlinux_magic dd LDLINUX_MAGIC - dd LDLINUX_MAGIC^HEXDATE - -; -; This area is patched by the installer. It is found by looking for -; LDLINUX_MAGIC, plus 8 bytes. -; -SUBVOL_MAX equ 256 -CURRENTDIR_MAX equ FILENAME_MAX - -patch_area: -DataSectors dw 0 ; Number of sectors (not including bootsec) -ADVSectors dw 0 ; Additional sectors for ADVs -LDLDwords dd 0 ; Total dwords starting at ldlinux_sys, -CheckSum dd 0 ; Checksum starting at ldlinux_sys - ; value = LDLINUX_MAGIC - [sum of dwords] -MaxTransfer dw 127 ; Max sectors to transfer -EPAPtr dw EPA - LDLINUX_SYS ; Pointer to the extended patch area - -; -; Extended patch area -- this is in .data16 so it doesn't occupy space in -; the first sector. Use this structure for anything that isn't used by -; the first sector itself. -; - section .data16 - alignz 2 -EPA: -ADVSecPtr dw ADVSec0 - LDLINUX_SYS -CurrentDirPtr dw CurrentDirName-LDLINUX_SYS ; Current directory name string -CurrentDirLen dw CURRENTDIR_MAX -SubvolPtr dw SubvolName-LDLINUX_SYS -SubvolLen dw SUBVOL_MAX -SecPtrOffset dw SectorPtrs-LDLINUX_SYS -SecPtrCnt dw (SectorPtrsEnd - SectorPtrs)/10 - -; -; Boot sector patch pointers -; -Sect1Ptr0Ptr dw Sect1Ptr0 - bootsec ; Pointers to Sector 1 location -Sect1Ptr1Ptr dw Sect1Ptr1 - bootsec -RAIDPatchPtr dw kaboom.again - bootsec ; Patch to INT 18h in RAID mode - -; -; Base directory name and subvolume, if applicable. -; -%define HAVE_CURRENTDIRNAME - global CurrentDirName, SubvolName -CurrentDirName times CURRENTDIR_MAX db 0 -SubvolName times SUBVOL_MAX db 0 - - section .init -ldlinux_ent: -; -; Note that some BIOSes are buggy and run the boot sector at 07C0:0000 -; instead of 0000:7C00 and the like. We don't want to add anything -; more to the boot sector, so it is written to not assume a fixed -; value in CS, but we don't want to deal with that anymore from now -; on. -; - sti ; In case of broken INT 13h BIOSes - -; -; Tell the user we got this far -; - mov si,syslinux_banner - call writestr_early - -; -; Checksum data thus far -; - mov si,ldlinux_sys - mov cx,SECTOR_SIZE >> 2 - mov edx,-LDLINUX_MAGIC -.checksum: - lodsd - add edx,eax - loop .checksum - mov [CheckSum],edx ; Save intermediate result - -; -; Tell the user if we're using EBIOS or CBIOS -; -print_bios: - mov si,cbios_name - cmp byte [getonesec.jmp+1],(getonesec_ebios-(getonesec.jmp+2)) - jne .cbios - mov si,ebios_name - mov byte [getlinsec.jmp+1],(getlinsec_ebios-(getlinsec.jmp+2)) -.cbios: - mov [BIOSName],si - call writestr_early - - section .earlybss -%define HAVE_BIOSNAME 1 -BIOSName resw 1 - - section .init -; -; Now we read the rest of LDLINUX.SYS. -; -load_rest: - lea esi,[SectorPtrs] - mov ebx,TEXT_START+2*SECTOR_SIZE ; Where we start loading - mov cx,[DataSectors] - dec cx ; Minus this sector - -.get_chunk: - jcxz .done - mov eax,[si] - mov edx,[si+4] - movzx ebp,word [si+8] - sub cx,bp - push ebx - shr ebx,4 ; Convert to a segment - mov es,bx - xor bx,bx - call getlinsec - pop ebx - shl ebp,SECTOR_SHIFT - add ebx,ebp - add si,10 - jmp .get_chunk - -.done: - -; -; All loaded up, verify that we got what we needed. -; Note: the checksum field is embedded in the checksum region, so -; by the time we get to the end it should all cancel out. -; -verify_checksum: - mov si,ldlinux_sys + SECTOR_SIZE - mov ecx,[LDLDwords] - sub ecx,SECTOR_SIZE >> 2 - mov eax,[CheckSum] -.checksum: - add eax,[si] - add si,4 - jnz .nowrap - ; Handle segment wrap - mov dx,ds - add dx,1000h - mov ds,dx -.nowrap: - dec ecx - jnz .checksum - - and eax,eax ; Should be zero - jz all_read ; We're cool, go for it! - -; -; Uh-oh, something went bad... -; - mov si,checksumerr_msg - call writestr_early - jmp kaboom - -; -; ----------------------------------------------------------------------------- -; Subroutines that have to be in the first sector -; ----------------------------------------------------------------------------- - - - -; -; getlinsec: load a sequence of BP floppy sector given by the linear sector -; number in EAX into the buffer at ES:BX. We try to optimize -; by loading up to a whole track at a time, but the user -; is responsible for not crossing a 64K boundary. -; (Yes, BP is weird for a count, but it was available...) -; -; On return, BX points to the first byte after the transferred -; block. -; -; This routine assumes CS == DS. -; - global getlinsec -getlinsec: - pushad - add eax,[Hidden] ; Add partition offset - adc edx,[Hidden+4] -.jmp: jmp strict short getlinsec_cbios - -; -; getlinsec_ebios: -; -; getlinsec implementation for EBIOS (EDD) -; -getlinsec_ebios: -.loop: - push bp ; Sectors left -.retry2: - call maxtrans ; Enforce maximum transfer size - movzx edi,bp ; Sectors we are about to read - mov cx,retry_count -.retry: - - ; Form DAPA on stack - push edx - push eax - push es - push bx - push di - push word 16 - mov si,sp - pushad - mov ah,42h ; Extended Read - push ds - push ss - pop ds - call xint13 - pop ds - popad - lea sp,[si+16] ; Remove DAPA - jc .error - pop bp - add eax,edi ; Advance sector pointer - adc edx,0 - sub bp,di ; Sectors left - shl di,SECTOR_SHIFT ; 512-byte sectors - add bx,di ; Advance buffer pointer - and bp,bp - jnz .loop - - popad - ret - -.error: - ; Some systems seem to get "stuck" in an error state when - ; using EBIOS. Doesn't happen when using CBIOS, which is - ; good, since some other systems get timeout failures - ; waiting for the floppy disk to spin up. - - pushad ; Try resetting the device - xor ax,ax - mov dl,[DriveNumber] - int 13h - popad - loop .retry ; CX-- and jump if not zero - - ;shr word [MaxTransfer],1 ; Reduce the transfer size - ;jnz .retry2 - - ; Total failure. Try falling back to CBIOS. - mov byte [getlinsec.jmp+1],(getlinsec_cbios-(getlinsec.jmp+2)) - ;mov byte [MaxTransfer],63 ; Max possibe CBIOS transfer - - pop bp - ; ... fall through ... - -; -; getlinsec_cbios: -; -; getlinsec implementation for legacy CBIOS -; -getlinsec_cbios: -.loop: - push edx - push eax - push bp - push bx - - movzx esi,word [bsSecPerTrack] - movzx edi,word [bsHeads] - ; - ; Dividing by sectors to get (track,sector): we may have - ; up to 2^18 tracks, so we need to use 32-bit arithmetric. - ; - div esi - xor cx,cx - xchg cx,dx ; CX <- sector index (0-based) - ; EDX <- 0 - ; eax = track # - div edi ; Convert track to head/cyl - - cmp eax,1023 ; Outside the CHS range? - ja kaboom - - ; - ; Now we have AX = cyl, DX = head, CX = sector (0-based), - ; BP = sectors to transfer, SI = bsSecPerTrack, - ; ES:BX = data target - ; - - call maxtrans ; Enforce maximum transfer size - - ; Must not cross track boundaries, so BP <= SI-CX - sub si,cx - cmp bp,si - jna .bp_ok - mov bp,si -.bp_ok: - - shl ah,6 ; Because IBM was STOOPID - ; and thought 8 bits were enough - ; then thought 10 bits were enough... - inc cx ; Sector numbers are 1-based, sigh - or cl,ah - mov ch,al - mov dh,dl - xchg ax,bp ; Sector to transfer count - mov ah,02h ; Read sectors - mov bp,retry_count -.retry: - pushad - call xint13 - popad - jc .error -.resume: - movzx ecx,al ; ECX <- sectors transferred - shl ax,SECTOR_SHIFT ; Convert sectors in AL to bytes in AX - pop bx - add bx,ax - pop bp - pop eax - pop edx - add eax,ecx - sub bp,cx - jnz .loop - popad - ret - -.error: - dec bp - jnz .retry - - xchg ax,bp ; Sectors transferred <- 0 - shr word [MaxTransfer],1 - jnz .resume - jmp kaboom - -maxtrans: - cmp bp,[MaxTransfer] - jna .ok - mov bp,[MaxTransfer] -.ok: ret - -; -; Checksum error message -; -checksumerr_msg db ' Load error - ', 0 ; Boot failed appended - -; -; BIOS type string -; -cbios_name db 'CHS', 0 ; CHS/CBIOS -ebios_name db 'EDD', 0 ; EDD/EBIOS - -; -; Debug routine -; -%ifdef debug -safedumpregs: - cmp word [Debug_Magic],0D00Dh - jnz nc_return - jmp dumpregs -%endif - -rl_checkpt equ $ ; Must be <= 8000h - -rl_checkpt_off equ ($-$$) -%ifndef DEPEND - %if rl_checkpt_off > 3F6h ; Need one extent - %assign rl_checkpt_overflow rl_checkpt_off - 3F6h - %error Sector 1 overflow by rl_checkpt_overflow bytes - %endif -%endif - -; -; Extent pointers... each extent contains an 8-byte LBA and an 2-byte -; sector count. In most cases, we will only ever need a handful of -; extents, but we have to assume a maximally fragmented system where each -; extent contains only one sector. -; - alignz 2 -MaxInitDataSize equ 96 << 10 -MaxLMA equ TEXT_START+SECTOR_SIZE+MaxInitDataSize -SectorPtrs zb 10*(MaxInitDataSize >> SECTOR_SHIFT) -SectorPtrsEnd equ $ - -; ---------------------------------------------------------------------------- -; End of code and data that have to be in the first sector -; ---------------------------------------------------------------------------- - - section .text16 -all_read: - ; We enter here with both DS and ES scrambled... - xor ax,ax - mov ds,ax - mov es,ax -; -; Let the user (and programmer!) know we got this far. This used to be -; in Sector 1, but makes a lot more sense here. -; - mov si,copyright_str - call writestr_early - - -; -; Insane hack to expand the DOS superblock to dwords -; -expand_super: - xor eax,eax - mov si,superblock - mov di,SuperInfo - mov cx,superinfo_size -.loop: - lodsw - dec si - stosd ; Store expanded word - xor ah,ah - stosd ; Store expanded byte - loop .loop - - -; -; Common initialization code -; -%include "init.inc" - - pushad - mov eax,ROOT_FS_OPS - movzx dx,byte [DriveNumber] - ; DH = 0: we are boot from disk not CDROM - mov ecx,[Hidden] - mov ebx,[Hidden+4] - mov si,[bsHeads] - mov di,[bsSecPerTrack] - movzx ebp,word [MaxTransfer] - pm_call fs_init - popad - - section .bss16 -SuperInfo resq 16 ; The first 16 bytes expanded 8 times - - section .text16 |