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authorH. Peter Anvin <hpa@zytor.com>2009-04-19 15:35:02 -0700
committerH. Peter Anvin <hpa@zytor.com>2009-04-19 15:35:02 -0700
commit449e02585d22040ae998a4b120f55f7e25b583a6 (patch)
treeb88246c994f7586967915e15c081b0fa34b6734b
parentce64bcb9e7ed34d7a54a79c8291f43563ba6a069 (diff)
downloadsyslinux.git-449e02585d22040ae998a4b120f55f7e25b583a6.tar.gz
syslinux.git-449e02585d22040ae998a4b120f55f7e25b583a6.tar.xz
syslinux.git-449e02585d22040ae998a4b120f55f7e25b583a6.zip
core: merge the startup code for disk-based derivatives
Merge the startup code for disk-based derivatives (currently SYSLINUX, EXTLINUX) into a single file. There is probably still additional shared code that should be merged, but this is a good start. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r--core/diskstart.inc681
-rw-r--r--core/extlinux.asm645
-rw-r--r--core/ldlinux.asm656
-rw-r--r--core/macros.inc32
4 files changed, 707 insertions, 1307 deletions
diff --git a/core/diskstart.inc b/core/diskstart.inc
new file mode 100644
index 00000000..c3881eab
--- /dev/null
+++ b/core/diskstart.inc
@@ -0,0 +1,681 @@
+; -----------------------------------------------------------------------
+;
+; Copyright 1994-2009 H. Peter Anvin - All Rights Reserved
+; Copyright 2009 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.
+;
+
+ ; Expanded superblock
+ section .bss
+ alignb 8
+SuperInfo resq 16 ; The first 16 bytes expanded 8 times
+
+ section .text
+;
+; 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 $-44-32 ; Start the stack here (grow down - 4K)
+PartInfo equ StackBuf ; Saved partition table entry
+FloppyTable equ PartInfo+16 ; Floppy info table (must follow PartInfo)
+OrigFDCTabPtr equ StackBuf-8 ; The 2nd high dword on the stack
+OrigESDI equ StackBuf-4 ; The high dword on the 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
+
+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 ax,ax
+ mov ss,ax
+ mov sp,StackBuf ; Just below BSS
+ push es ; Save initial ES:DI -> $PnP pointer
+ push di
+ mov es,ax
+;
+; DS:SI may contain a partition table entry. Preserve it for us.
+;
+ mov cx,8 ; Save partition info
+ mov di,PartInfo
+ rep movsw
+
+ mov ds,ax ; 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
+ mov [DriveNumber],dl ; Save drive number in DL
+ and dl,dl ; If floppy disk (00-7F), assume no
+ ; partition table
+ js harddisk
+
+floppy:
+ 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-8],cl
+ ; AX == 0 here
+ 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.
+;
+; Would it be better to zero out bsHidden if we don't have a partition table?
+;
+; Note: di points to beyond the end of PartInfo
+;
+harddisk:
+ test byte [di-16],7Fh ; Sanity check: "active flag" should
+ jnz no_partition ; be 00 or 80
+ mov eax,[di-8] ; Partition offset (dword)
+ mov [bsHidden],eax
+no_partition:
+;
+; 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 [getlinsec.jmp+1],(getlinsec_ebios-(getlinsec.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,[FirstSector] ; Sector start
+ 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 ldlinux_ent
+
+;
+; getonesec: get one disk sector
+;
+getonesec:
+ mov bp,1 ; One sector
+ ; Fall through
+
+;
+; 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, 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.
+;
+getlinsec:
+ add eax,[bsHidden] ; Add partition offset
+ xor edx,edx ; Zero-extend LBA (eventually allow 64 bits)
+
+.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 dl,[DriveNumber]
+ push ds
+ push ss
+ pop ds ; DS <- SS
+ mov ah,42h ; Extended Read
+ int 13h
+ pop ds
+ popad
+ lea sp,[si+16] ; Remove DAPA
+ jc .error
+ pop bp
+ add eax,edi ; Advance sector pointer
+ sub bp,di ; Sectors left
+ shl di,SECTOR_SHIFT ; 512-byte sectors
+ add bx,di ; Advance buffer pointer
+ and bp,bp
+ jnz .loop
+
+ 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
+
+ ; We should test this, but it doesn't fit...
+ ; cmp eax,1023
+ ; ja .error
+
+ ;
+ ; 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
+ mov dl,[DriveNumber]
+ xchg ax,bp ; Sector to transfer count
+ mov ah,02h ; Read sectors
+ mov bp,retry_count
+.retry:
+ pushad
+ int 13h
+ 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
+ ret
+
+.error:
+ dec bp
+ jnz .retry
+
+ xchg ax,bp ; Sectors transferred <- 0
+ shr word [MaxTransfer],1
+ jnz .resume
+ ; Fall through to disk_error
+
+;
+; kaboom: write a message and bail out.
+;
+disk_error:
+kaboom:
+ xor si,si
+ mov ss,si
+ mov sp,StackBuf-4 ; 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
+
+ ; Write error message, this assumes screen page 0
+.loop: lodsb
+ and al,al
+ jz .done
+ mov ah,0Eh ; Write to screen as TTY
+ mov bx,0007h ; Attribute
+ int 10h
+ jmp short .loop
+.done:
+ cbw ; AH <- 0
+.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: jmp short .norge ; If int 19h returned; this is the end
+
+;
+; Truncate BP to MaxTransfer
+;
+maxtrans:
+ cmp bp,[MaxTransfer]
+ jna .ok
+ mov bp,[MaxTransfer]
+.ok: ret
+
+;
+; Error message on failure
+;
+bailmsg: db 'Boot error', 0Dh, 0Ah, 0
+
+ ; This fails if the boot sector overflows
+ zb 1F8h-($-$$)
+
+FirstSector dd 0xDEADBEEF ; Location of sector 1
+MaxTransfer dw 0x007F ; Max transfer size
+
+; This field will be filled in 0xAA55 by the installer, but we abuse it
+; to house a pointer to the INT 16h instruction at
+; kaboom.again, which gets patched to INT 18h in RAID mode.
+bootsignature dw kaboom.again-bootsec
+
+;
+; ===========================================================================
+; End of boot sector
+; ===========================================================================
+; Start of LDLINUX.SYS
+; ===========================================================================
+
+ldlinux_sys:
+
+syslinux_banner db 0Dh, 0Ah
+ db MY_NAME, ' ', VERSION_STR, ' ', DATE_STR, ' ', 0
+ db 0Dh, 0Ah, 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.
+;
+patch_area:
+LDLDwords dw 0 ; Total dwords starting at ldlinux_sys,
+ ; not including ADVs
+LDLSectors dw 0 ; Number of sectors - (bootsec+this sec)
+ ; but including any ADVs
+CheckSum dd 0 ; Checksum starting at ldlinux_sys
+ ; value = LDLINUX_MAGIC - [sum of dwords]
+%if IS_EXTLINUX
+CurrentDir dd 2 ; "Current" directory inode number
+%endif
+
+; Space for up to 64 sectors, the theoretical maximum
+SectorPtrs times 64 dd 0
+
+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.
+;
+ jmp 0:.next
+.next:
+
+;
+; Tell the user we got this far
+;
+ mov si,syslinux_banner
+ call writestr_early
+
+;
+; Tell the user if we're using EBIOS or CBIOS
+;
+print_bios:
+ mov si,cbios_name
+ cmp byte [getlinsec.jmp+1],(getlinsec_ebios-(getlinsec.jmp+2))
+ jne .cbios
+ mov si,ebios_name
+.cbios:
+ mov [BIOSName],si
+ call writestr_early
+
+ section .bss
+%define HAVE_BIOSNAME 1
+BIOSName resw 1
+
+ section .text
+;
+; Now we read the rest of LDLINUX.SYS. Don't bother loading the first
+; sector again, though.
+;
+load_rest:
+ mov si,SectorPtrs
+ mov bx,7C00h+2*SECTOR_SIZE ; Where we start loading
+ mov cx,[LDLSectors]
+
+.get_chunk:
+ jcxz .done
+ xor bp,bp
+ lodsd ; First sector of this chunk
+
+ mov edx,eax
+
+.make_chunk:
+ inc bp
+ dec cx
+ jz .chunk_ready
+ inc edx ; Next linear sector
+ cmp [si],edx ; Does it match
+ jnz .chunk_ready ; If not, this is it
+ add si,4 ; If so, add sector to chunk
+ jmp short .make_chunk
+
+.chunk_ready:
+ call getlinsecsr
+ shl bp,SECTOR_SHIFT
+ add bx,bp
+ 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
+ mov cx,[LDLDwords]
+ mov edx,-LDLINUX_MAGIC
+.checksum:
+ lodsd
+ add edx,eax
+ loop .checksum
+
+ and edx,edx ; 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
+; -----------------------------------------------------------------------------
+
+;
+;
+; 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
+
+
+; getlinsecsr: save registers, call getlinsec, restore registers
+;
+getlinsecsr: pushad
+ call getlinsec
+ popad
+ ret
+
+;
+; Checksum error message
+;
+checksumerr_msg db ' Load error - ', 0 ; Boot failed appended
+
+;
+; BIOS type string
+;
+cbios_name db 'CBIOS', 0
+ebios_name db 'EBIOS', 0
+
+;
+; 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 > 400h
+%error "Sector 1 overflow"
+%endif
+%endif
+
+; ----------------------------------------------------------------------------
+; End of code and data that have to be in the first sector
+; ----------------------------------------------------------------------------
+
+all_read:
+;
+; 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
+
+;
+; Fall through to the mainline code...
+;
+ section .text
diff --git a/core/extlinux.asm b/core/extlinux.asm
index a9e51d57..d54bad51 100644
--- a/core/extlinux.asm
+++ b/core/extlinux.asm
@@ -104,9 +104,7 @@ trackbuf resb trackbufsize ; Track buffer goes here
section .bss
SuperBlock resb 1024 ; ext2 superblock
-SuperInfo resq 16 ; DOS superblock expanded
ClustSize resd 1 ; Bytes/cluster ("block")
-SecPerClust resd 1 ; Sectors/cluster
ClustMask resd 1 ; Sectors/cluster - 1
PtrsPerBlock1 resd 1 ; Pointers/cluster
PtrsPerBlock2 resd 1 ; (Pointers/cluster)^2
@@ -117,649 +115,10 @@ ClustByteShift resb 1 ; Shift count for bytes/cluster
alignb open_file_t_size
Files resb MAX_OPEN*open_file_t_size
- section .text
-;
-; 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 $-44-32 ; Start the stack here (grow down - 4K)
-PartInfo equ StackBuf ; Saved partition table entry
-FloppyTable equ PartInfo+16 ; Floppy info table (must follow PartInfo)
-OrigFDCTabPtr equ StackBuf-8 ; The 2nd high dword on the stack
-OrigESDI equ StackBuf-4 ; The high dword on the 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 'EXTLINUX' ; The SYS command sets this, so...
-;
-; 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
- ;
- zb 54 ; FAT12/16 need 26 more bytes,
- ; FAT32 need 54 more bytes
-superblock_len equ $-superblock
-
-;
-; 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 ax,ax
- mov ss,ax
- mov sp,StackBuf ; Just below BSS
- push es ; Save initial ES:DI -> $PnP pointer
- push di
- mov es,ax
-;
-; DS:SI may contain a partition table entry. Preserve it for us.
-;
- mov cx,8 ; Save partition info
- mov di,PartInfo
- rep movsw
-
- mov ds,ax ; 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
- mov [DriveNumber],dl ; Save drive number in DL
- and dl,dl ; If floppy disk (00-7F), assume no
- ; partition table
- js harddisk
-
-floppy:
- 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-8],cl
- ; AX == 0 here
- 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.
-;
-; Would it be better to zero out bsHidden if we don't have a partition table?
-;
-; Note: di points to beyond the end of PartInfo
-;
-harddisk:
- test byte [di-16],7Fh ; Sanity check: "active flag" should
- jnz no_partition ; be 00 or 80
- mov eax,[di-8] ; Partition offset (dword)
- mov [bsHidden],eax
-no_partition:
-;
-; 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 [getlinsec.jmp+1],(getlinsec_ebios-(getlinsec.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,[FirstSector] ; Sector start
- 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 ldlinux_ent
-
-;
-; getonesec: get one disk sector
-;
-getonesec:
- mov bp,1 ; One sector
- ; Fall through
-
-;
-; 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, 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.
-;
-getlinsec:
- add eax,[bsHidden] ; Add partition offset
- xor edx,edx ; Zero-extend LBA (eventually allow 64 bits)
-
-.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 dl,[DriveNumber]
- push ds
- push ss
- pop ds ; DS <- SS
- mov ah,42h ; Extended Read
- int 13h
- pop ds
- popad
- lea sp,[si+16] ; Remove DAPA
- jc .error
- pop bp
- add eax,edi ; Advance sector pointer
- sub bp,di ; Sectors left
- shl di,SECTOR_SHIFT ; 512-byte sectors
- add bx,di ; Advance buffer pointer
- and bp,bp
- jnz .loop
-
- 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
-
- ; We should test this, but it doesn't fit...
- ; cmp eax,1023
- ; ja .error
-
- ;
- ; 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
- mov dl,[DriveNumber]
- xchg ax,bp ; Sector to transfer count
- mov ah,02h ; Read sectors
- mov bp,retry_count
-.retry:
- pushad
- int 13h
- 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
- ret
-
-.error:
- dec bp
- jnz .retry
-
- xchg ax,bp ; Sectors transferred <- 0
- shr word [MaxTransfer],1
- jnz .resume
- ; Fall through to disk_error
-
-;
-; kaboom: write a message and bail out.
-;
-disk_error:
-kaboom:
- xor si,si
- mov ss,si
- mov sp,StackBuf-4 ; 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
-
- ; Write error message, this assumes screen page 0
-.loop: lodsb
- and al,al
- jz .done
- mov ah,0Eh ; Write to screen as TTY
- mov bx,0007h ; Attribute
- int 10h
- jmp short .loop
-.done:
- cbw ; AH <- 0
-.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: jmp short .norge ; If int 19h returned; this is the end
-
-;
-; Truncate BP to MaxTransfer
-;
-maxtrans:
- cmp bp,[MaxTransfer]
- jna .ok
- mov bp,[MaxTransfer]
-.ok: ret
-
-;
-; Error message on failure
-;
-bailmsg: db 'Boot error', 0Dh, 0Ah, 0
-
- ; This fails if the boot sector overflows
- zb 1F8h-($-$$)
-
-FirstSector dd 0xDEADBEEF ; Location of sector 1
-MaxTransfer dw 0x007F ; Max transfer size
-
-; This field will be filled in 0xAA55 by the installer, but we abuse it
-; to house a pointer to the INT 16h instruction at
-; kaboom.again, which gets patched to INT 18h in RAID mode.
-bootsignature dw kaboom.again-bootsec
-
-;
-; ===========================================================================
-; End of boot sector
-; ===========================================================================
-; Start of LDLINUX.SYS
-; ===========================================================================
-
-ldlinux_sys:
-
-syslinux_banner db 0Dh, 0Ah
- db 'EXTLINUX '
- db VERSION_STR, ' ', DATE_STR, ' ', 0
- db 0Dh, 0Ah, 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.
-;
-patch_area:
-LDLDwords dw 0 ; Total dwords starting at ldlinux_sys,
- ; not including ADVs
-LDLSectors dw 0 ; Number of sectors, not including
- ; bootsec & this sec, but including the two ADVs
-CheckSum dd 0 ; Checksum starting at ldlinux_sys
- ; value = LDLINUX_MAGIC - [sum of dwords]
-CurrentDir dd 2 ; "Current" directory inode number
-
-; Space for up to 64 sectors, the theoretical maximum
-SectorPtrs times 64 dd 0
-
-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.
-;
- jmp 0:.next
-.next:
-
-;
-; Tell the user we got this far
-;
- mov si,syslinux_banner
- call writestr_early
-
-;
-; Tell the user if we're using EBIOS or CBIOS
-;
-print_bios:
- mov si,cbios_name
- cmp byte [getlinsec.jmp+1],(getlinsec_ebios-(getlinsec.jmp+2))
- jne .cbios
- mov si,ebios_name
-.cbios:
- mov [BIOSName],si
- call writestr_early
-
- section .bss
-%define HAVE_BIOSNAME 1
-BIOSName resw 1
-
- section .text
-;
-; Now we read the rest of LDLINUX.SYS. Don't bother loading the first
-; sector again, though.
-;
-load_rest:
- mov si,SectorPtrs
- mov bx,7C00h+2*SECTOR_SIZE ; Where we start loading
- mov cx,[LDLSectors]
-
-.get_chunk:
- jcxz .done
- xor bp,bp
- lodsd ; First sector of this chunk
-
- mov edx,eax
-
-.make_chunk:
- inc bp
- dec cx
- jz .chunk_ready
- inc edx ; Next linear sector
- cmp [si],edx ; Does it match
- jnz .chunk_ready ; If not, this is it
- add si,4 ; If so, add sector to chunk
- jmp short .make_chunk
-
-.chunk_ready:
- call getlinsecsr
- shl bp,SECTOR_SHIFT
- add bx,bp
- 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.
+; Common bootstrap code for disk-based derivatives
;
-verify_checksum:
- mov si,ldlinux_sys
- mov cx,[LDLDwords]
- mov edx,-LDLINUX_MAGIC
-.checksum:
- lodsd
- add edx,eax
- loop .checksum
-
- and edx,edx ; 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
-; -----------------------------------------------------------------------------
-
-;
-;
-; 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
-
-
-; getlinsecsr: save registers, call getlinsec, restore registers
-;
-getlinsecsr: pushad
- call getlinsec
- popad
- ret
-
-;
-; Checksum error message
-;
-checksumerr_msg db ' Load error - ', 0 ; Boot failed appended
-
-;
-; BIOS type string
-;
-cbios_name db 'CBIOS', 0
-ebios_name db 'EBIOS', 0
-
-;
-; 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 > 400h
-%error "Sector 1 overflow"
-%endif
-%endif
-
-; ----------------------------------------------------------------------------
-; End of code and data that have to be in the first sector
-; ----------------------------------------------------------------------------
-
-all_read:
-;
-; 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
+%include "diskstart.inc"
;
; Load the real (ext2) superblock; 1024 bytes long at offset 1024
diff --git a/core/ldlinux.asm b/core/ldlinux.asm
index 8a3ce82a..4da9c153 100644
--- a/core/ldlinux.asm
+++ b/core/ldlinux.asm
@@ -117,11 +117,7 @@ trackbuf resb trackbufsize ; Track buffer goes here
; ends at 2800h
section .bss
- alignb 8
-
- ; Expanded superblock
-SuperInfo equ $
- resq 16 ; The first 16 bytes expanded 8 times
+ alignb 4
FAT resd 1 ; Location of (first) FAT
RootDirArea resd 1 ; Location of root directory area
RootDir resd 1 ; Location of root directory proper
@@ -138,656 +134,10 @@ ClustByteShift resb 1 ; Shift count for bytes/cluster
alignb open_file_t_size
Files resb MAX_OPEN*open_file_t_size
- section .text
-;
-; 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 $-44-32 ; Start the stack here (grow down - 4K)
-PartInfo equ StackBuf ; Saved partition table entry
-FloppyTable equ PartInfo+16 ; Floppy info table (must follow PartInfo)
-OrigFDCTabPtr equ StackBuf-8 ; The 2nd high dword on the stack
-OrigESDI equ StackBuf-4 ; The high dword on the 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 'SYSLINUX' ; The SYS command sets this, so...
-;
-; 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
-
-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 ax,ax
- mov ss,ax
- mov sp,StackBuf ; Just below BSS
- push es ; Save initial ES:DI -> $PnP pointer
- push di
- mov es,ax
-;
-; DS:SI may contain a partition table entry. Preserve it for us.
-;
- mov cx,8 ; Save partition info
- mov di,PartInfo
- rep movsw
-
- mov ds,ax ; 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
- mov [DriveNumber],dl ; Save drive number in DL
- and dl,dl ; If floppy disk (00-7F), assume no
- ; partition table
- js harddisk
-
-floppy:
- 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-8],cl
- ; AX == 0 here
- 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.
-;
-; Would it be better to zero out bsHidden if we don't have a partition table?
-;
-; Note: di points to beyond the end of PartInfo
-;
-harddisk:
- test byte [di-16],7Fh ; Sanity check: "active flag" should
- jnz no_partition ; be 00 or 80
- mov eax,[di-8] ; Partition offset (dword)
- mov [bsHidden],eax
-no_partition:
-;
-; 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 [getlinsec.jmp+1],(getlinsec_ebios-(getlinsec.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,[FirstSector] ; Sector start
- 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 ldlinux_ent
-
-;
-; getonesec: get one disk sector
-;
-getonesec:
- mov bp,1 ; One sector
- ; Fall through
-
-;
-; 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, 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.
-;
-getlinsec:
- add eax,[bsHidden] ; Add partition offset
- xor edx,edx ; Zero-extend LBA (eventually allow 64 bits)
-
-.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 dl,[DriveNumber]
- push ds
- push ss
- pop ds ; DS <- SS
- mov ah,42h ; Extended Read
- int 13h
- pop ds
- popad
- lea sp,[si+16] ; Remove DAPA
- jc .error
- pop bp
- add eax,edi ; Advance sector pointer
- sub bp,di ; Sectors left
- shl di,SECTOR_SHIFT ; 512-byte sectors
- add bx,di ; Advance buffer pointer
- and bp,bp
- jnz .loop
-
- 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
+; Common bootstrap code for disk-based derivatives
;
-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
-
- ; We should test this, but it doesn't fit...
- ; cmp eax,1023
- ; ja .error
-
- ;
- ; 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
- mov dl,[DriveNumber]
- xchg ax,bp ; Sector to transfer count
- mov ah,02h ; Read sectors
- mov bp,retry_count
-.retry:
- pushad
- int 13h
- 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
- ret
-
-.error:
- dec bp
- jnz .retry
-
- xchg ax,bp ; Sectors transferred <- 0
- shr word [MaxTransfer],1
- jnz .resume
- ; Fall through to disk_error
-
-;
-; kaboom: write a message and bail out.
-;
-disk_error:
-kaboom:
- xor si,si
- mov ss,si
- mov sp,StackBuf-4 ; 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
-
- ; Write error message, this assumes screen page 0
-.loop: lodsb
- and al,al
- jz .done
- mov ah,0Eh ; Write to screen as TTY
- mov bx,0007h ; Attribute
- int 10h
- jmp short .loop
-.done:
- cbw ; AH <- 0
-.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: jmp short .norge ; If int 19h returned; this is the end
-
-;
-; Truncate BP to MaxTransfer
-;
-maxtrans:
- cmp bp,[MaxTransfer]
- jna .ok
- mov bp,[MaxTransfer]
-.ok: ret
-
-;
-; Error message on failure
-;
-bailmsg: db 'Boot error', 0Dh, 0Ah, 0
-
- ; This fails if the boot sector overflows
- zb 1F8h-($-$$)
-
-FirstSector dd 0xDEADBEEF ; Location of sector 1
-MaxTransfer dw 0x007F ; Max transfer size
-
-; This field will be filled in 0xAA55 by the installer, but we abuse it
-; to house a pointer to the INT 16h instruction at
-; kaboom.again, which gets patched to INT 18h in RAID mode.
-bootsignature dw kaboom.again-bootsec
-
-;
-; ===========================================================================
-; End of boot sector
-; ===========================================================================
-; Start of LDLINUX.SYS
-; ===========================================================================
-
-ldlinux_sys:
-
-syslinux_banner db 0Dh, 0Ah
-%if IS_MDSLINUX
- db 'MDSLINUX '
-%else
- db 'SYSLINUX '
-%endif
- db VERSION_STR, ' ', DATE_STR, ' ', 0
- db 0Dh, 0Ah, 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.
-;
-patch_area:
-LDLDwords dw 0 ; Total dwords starting at ldlinux_sys
-LDLSectors dw 0 ; Number of sectors - (bootsec+this sec)
-CheckSum dd 0 ; Checksum starting at ldlinux_sys
- ; value = LDLINUX_MAGIC - [sum of dwords]
-
-; Space for up to 64 sectors, the theoretical maximum
-SectorPtrs times 64 dd 0
-
-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.
-;
- jmp 0:.next
-.next:
-
-;
-; Tell the user we got this far
-;
- mov si,syslinux_banner
- call writestr_early
-
-;
-; Tell the user if we're using EBIOS or CBIOS
-;
-print_bios:
- mov si,cbios_name
- cmp byte [getlinsec.jmp+1],(getlinsec_ebios-(getlinsec.jmp+2))
- jne .cbios
- mov si,ebios_name
-.cbios:
- mov [BIOSName],si
- call writestr_early
-
- section .bss
-%define HAVE_BIOSNAME 1
-BIOSName resw 1
-
- section .text
-;
-; Now we read the rest of LDLINUX.SYS. Don't bother loading the first
-; sector again, though.
-;
-load_rest:
- mov si,SectorPtrs
- mov bx,7C00h+2*SECTOR_SIZE ; Where we start loading
- mov cx,[LDLSectors]
-
-.get_chunk:
- jcxz .done
- xor bp,bp
- lodsd ; First sector of this chunk
-
- mov edx,eax
-
-.make_chunk:
- inc bp
- dec cx
- jz .chunk_ready
- inc edx ; Next linear sector
- cmp [si],edx ; Does it match
- jnz .chunk_ready ; If not, this is it
- add si,4 ; If so, add sector to chunk
- jmp short .make_chunk
-
-.chunk_ready:
- call getlinsecsr
- shl bp,SECTOR_SHIFT
- add bx,bp
- 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
- mov cx,[LDLDwords]
- mov edx,-LDLINUX_MAGIC
-.checksum:
- lodsd
- add edx,eax
- loop .checksum
-
- and edx,edx ; 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
-; -----------------------------------------------------------------------------
-
-;
-;
-; 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
-
-
-; getlinsecsr: save registers, call getlinsec, restore registers
-;
-getlinsecsr: pushad
- call getlinsec
- popad
- ret
-
-;
-; Checksum error message
-;
-checksumerr_msg db ' Load error - ', 0 ; Boot failed appended
-
-;
-; BIOS type string
-;
-cbios_name db 'CBIOS', 0
-ebios_name db 'EBIOS', 0
-
-;
-; 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 > 400h
-%error "Sector 1 overflow"
-%endif
-%endif
-
-; ----------------------------------------------------------------------------
-; End of code and data that have to be in the first sector
-; ----------------------------------------------------------------------------
-
-all_read:
-;
-; 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 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
+%include "diskstart.inc"
;
; Compute some information about this filesystem.
diff --git a/core/macros.inc b/core/macros.inc
index f3727c24..1c300583 100644
--- a/core/macros.inc
+++ b/core/macros.inc
@@ -24,20 +24,30 @@
; Identify the module we're compiling; the "correct" should be defined
; in the module itself to 1
;
-%ifndef IS_SYSLINUX
-%define IS_SYSLINUX 0
+%ifdef IS_SYSLINUX
+ %define MY_NAME 'SYSLINUX'
+%else
+ %define IS_SYSLINUX 0
%endif
-%ifndef IS_MDSLINUX
-%define IS_MDSLINUX 0
+%ifdef IS_MDSLINUX
+ %define MY_NAME 'MDSLINUX'
+%else
+ %define IS_MDSLINUX 0
%endif
-%ifndef IS_PXELINUX
-%define IS_PXELINUX 0
+%ifdef IS_PXELINUX
+ %define MY_NAME 'PXELINUX'
+%else
+ %define IS_PXELINUX 0
%endif
-%ifndef IS_ISOLINUX
-%define IS_ISOLINUX 0
+%ifdef IS_ISOLINUX
+ %define MY_NAME 'ISOLINUX'
+%else
+ %define IS_ISOLINUX 0
%endif
-%ifndef IS_EXTLINUX
-%define IS_EXTLINUX 0
+%ifdef IS_EXTLINUX
+ %define MY_NAME 'EXTLINUX'
+%else
+ %define IS_EXTLINUX 0
%endif
;
@@ -72,7 +82,7 @@
%assign %$v %1
%if %$v == 0
db '0'
- %else
+ %else
%assign %$dcount 0
%assign %$n %$v
%assign %$d 1