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>

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