From: hpa <hpa>
Date: Tue, 11 Jun 2002 05:48:29 +0000 (+0000)
Subject: Add an API for COMBOOT images, and add support for "COM32" -- 32-bit
X-Git-Tag: syslinux-3.11~685
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=abac6f53695c0b99e0235ca3da81ab3cd822f475;p=platform%2Fupstream%2Fsyslinux.git

Add an API for COMBOOT images, and add support for "COM32" -- 32-bit
linear .com files.
---

diff --git a/Makefile b/Makefile
index 761dd7e..a3cd083 100644
--- a/Makefile
+++ b/Makefile
@@ -41,12 +41,13 @@ CSRC    = syslinux.c gethostip.c
 NASMSRC  = ldlinux.asm syslinux.asm copybs.asm \
 	  pxelinux.asm mbr.asm isolinux.asm isolinux-debug.asm
 SOURCES = $(CSRC) $(NASMSRC) *.inc
-BTARGET = kwdhash.gen ldlinux.bss ldlinux.sys ldlinux.bin \
+BTARGET = kwdhash.gen version.gen ldlinux.bss ldlinux.sys ldlinux.bin \
 	  pxelinux.0 mbr.bin isolinux.bin isolinux-debug.bin
 ITARGET = syslinux.com syslinux copybs.com gethostip
 DOCS    = COPYING NEWS README TODO *.doc sample
 OTHER   = Makefile bin2c.pl now.pl genhash.pl keywords findpatch.pl \
-	  keytab-lilo.pl version sys2ansi.pl ppmtolss16 lss16toppm memdisk
+	  keytab-lilo.pl version version.pl sys2ansi.pl \
+	  ppmtolss16 lss16toppm memdisk
 OBSOLETE = pxelinux.bin
 
 # Things to install in /usr/bin
@@ -79,22 +80,22 @@ samples:
 memdisk:
 	$(MAKE) -C memdisk all
 
+version.gen: version version.pl
+	$(PERL) version.pl version
+
 kwdhash.gen: keywords genhash.pl
 	$(PERL) genhash.pl < keywords > kwdhash.gen
 
-ldlinux.bin: ldlinux.asm kwdhash.gen
-	$(NASM) -f bin -dVERSION="'$(VERSION)'" -dDATE_STR="'$(DATE)'" \
-		-dHEXDATE="$(HEXDATE)" \
+ldlinux.bin: ldlinux.asm kwdhash.gen version.gen
+	$(NASM) -f bin -DDATE_STR="'$(DATE)'" -DHEXDATE="$(HEXDATE)" \
 		-l ldlinux.lst -o ldlinux.bin ldlinux.asm
 
-pxelinux.bin: pxelinux.asm kwdhash.gen
-	$(NASM) -f bin -dVERSION="'$(VERSION)'" -dDATE_STR="'$(DATE)'" \
-		-dHEXDATE="$(HEXDATE)" \
+pxelinux.bin: pxelinux.asm kwdhash.gen version.gen
+	$(NASM) -f bin -DDATE_STR="'$(DATE)'" -DHEXDATE="$(HEXDATE)" \
 		-l pxelinux.lst -o pxelinux.bin pxelinux.asm
 
-isolinux.bin: isolinux.asm kwdhash.gen
-	$(NASM) -f bin -dVERSION="'$(VERSION)'" -dDATE_STR="'$(DATE)'" \
-		-dHEXDATE="$(HEXDATE)" \
+isolinux.bin: isolinux.asm kwdhash.gen version.gen
+	$(NASM) -f bin -DDATE_STR="'$(DATE)'" -DHEXDATE="$(HEXDATE)" \
 		-l isolinux.lst -o isolinux.bin isolinux.asm
 
 pxelinux.0: pxelinux.bin
@@ -102,8 +103,7 @@ pxelinux.0: pxelinux.bin
 
 # Special verbose version of isolinux.bin
 isolinux-debug.bin: isolinux-debug.asm kwdhash.gen
-	$(NASM) -f bin -dVERSION="'$(VERSION)'" -dDATE_STR="'$(DATE)'" \
-		-dHEXDATE="$(HEXDATE)" \
+	$(NASM) -f bin -DDATE_STR="'$(DATE)'" -DHEXDATE="$(HEXDATE)" \
 		-l isolinux-debug.lst -o isolinux-debug.bin isolinux-debug.asm
 
 ldlinux.bss: ldlinux.bin
@@ -136,7 +136,8 @@ syslinux: syslinux.o bootsect_bin.o ldlinux_bin.o
 		syslinux.o bootsect_bin.o ldlinux_bin.o
 
 syslinux.o: syslinux.c patch.offset
-	$(CC) $(INCLUDE) $(CFLAGS) -DPATCH_OFFSET=`cat patch.offset` -c -o $@ $<
+	$(CC) $(INCLUDE) $(CFLAGS) -DPATCH_OFFSET=`cat patch.offset` \
+		-c -o $@ $<
 
 gethostip.o: gethostip.c
 
diff --git a/NEWS b/NEWS
index aa7b920..024a0cd 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,11 @@
 Starting with 1.47, changes marked with SYSLINUX/PXELINUX/ISOLINUX
 apply to that specific program only; other changes apply to both.
 
+Changes in 2.00:
+	* ALL: Add support for "COM32" (32-bit COMBOOT) images.
+	* ALL: Add an API for COMBOOT/COM32 images.  See comboot.doc
+	  for details.
+
 Changes in 1.75:
 	* ALL: NASM 0.98.32 or later is now required to build
 	  SYSLINUX from sources.
diff --git a/bcopy32.inc b/bcopy32.inc
index d81f00b..c3be39a 100644
--- a/bcopy32.inc
+++ b/bcopy32.inc
@@ -43,6 +43,11 @@ bcopy_gdt:	dw bcopy_gdt_size-1	; Null descriptor - contains GDT
 		dd 008f9300h		; present, dpl 0, cover all 4G
 		dd 0000ffffh		; Data segment, use16, read/write,
 		dd 00009300h		; present, dpl 0, cover 64K
+		; The rest are used for COM32 only
+		dd 0000ffffh		; Code segment, use32, readable,
+		dd 00cf9b00h		; present, dpl 0, cover all 4G
+		dd 0000ffffh		; Data segment, use32, read/write,
+		dd 00cf9300h		; present, dpl 0, cover all 4G
 bcopy_gdt_size:	equ $-bcopy_gdt
 
 ;
diff --git a/com32.inc b/com32.inc
new file mode 100644
index 0000000..ac0440f
--- /dev/null
+++ b/com32.inc
@@ -0,0 +1,319 @@
+;; $Id$
+;; -----------------------------------------------------------------------
+;;   
+;;   Copyright 1994-2002 H. Peter Anvin - All Rights Reserved
+;;
+;;   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., 53 Temple Place Ste 330,
+;;   Bostom MA 02111-1307, USA; either version 2 of the License, or
+;;   (at your option) any later version; incorporated herein by reference.
+;;
+;; -----------------------------------------------------------------------
+
+;;
+;; com32.inc
+;;
+;; Common code for running a COM32 image
+;;
+
+;
+; Load a COM32 image.  A COM32 image is the 32-bit analogue to a DOS
+; .com file.  A COM32 image is loaded at address 0x101000, with %esp
+; set to the high end of usable memory.
+;
+; A COM32 image should begin with the magic bytes:
+; B8 FF 4C CD 21, which is "mov eax,0x21cd4cff" in 32-bit mode and
+; "mov ax,0x4cff; int 0x21" in 16-bit mode.  This will abort the
+; program with an error if run in 16-bit mode.
+;
+pm_idt:		equ 0x100000
+pm_entry:	equ 0x101000
+
+		bits 16
+		align 2
+com32_pmidt:
+		dw 8*256		; Limit
+		dd pm_idt		; Address
+
+com32_rmidt:
+		dw 0ffffh		; Limit
+		dd 0			; Address
+
+is_com32_image:
+		call highmemsize	; We need the high memory size...
+		call comboot_setup_api	; Set up the COMBOOT-style API
+
+		mov edi,pm_entry	; Load address
+		xchg eax,edx		; Gotta fix this insanity...
+		shl eax,16
+		mov ax,dx
+		call load_high
+		call crlf
+
+com32_start:
+		mov ebx,com32_call_start	; Where to go in PM
+
+com32_enter_pm:
+		mov [SavedSSSP],sp
+		mov [SavedSSSP+2],ss
+
+		cli
+		cld
+		call a20_test
+		jnz .a20ok
+		call enable_a20
+
+.a20ok:
+		lgdt [bcopy_gdt]	; We can use the same GDT just fine
+		lidt [com32_pmidt]	; Set up the IDT
+		mov eax,cr0
+		or al,1
+		mov cr0,eax		; Enter protected mode
+		jmp 20h:.in_pm
+		
+		bits 32
+.in_pm:
+		xor eax,eax		; Available for future use...
+		mov fs,eax
+		mov gs,eax
+
+		mov al,28h		; Set up data segments
+		mov es,eax
+		mov ds,eax
+		mov ss,eax
+
+		mov esp,[PMESP]		; Load protmode %esp if available
+		jmp ebx			; Go to where we need to go
+
+;
+; This is invoked right before the actually starting the COM32
+; progam, in 32-bit mode...
+;
+com32_call_start:
+		;
+		; Point the stack to the end of high memory
+		;
+		mov esp,[word HighMemSize]
+
+		;
+		; Set up the protmode IDT and the interrupt jump buffers
+		; We set these up in the system area at 0x100000,
+		; but we could also put them beyond the stack.
+		;
+		mov edi,pm_idt
+
+		; Form an interrupt gate descriptor
+		mov eax,0x00200000+((pm_idt+8*256)&0x0000ffff)
+		mov ebx,0x0000ee00+((pm_idt+8*256)&0xffff0000)
+		xor ecx,ecx
+		inc ch				; ecx <- 256
+
+		push ecx
+.make_idt:
+		stosd
+		add eax,8
+		xchg eax,ebx
+		stosd
+		xchg eax,ebx
+		loop .make_idt
+
+		pop ecx
+
+		; Each entry in the interrupt jump buffer contains
+		; the following instructions:
+		;
+		; 00000000 60                pushad
+		; 00000001 B0xx              mov al,<interrupt#>
+		; 00000003 E9xxxxxxxx        jmp com32_handle_interrupt
+
+		mov eax,0e900b060h
+		mov ebx,com32_handle_interrupt-(pm_idt+8*256+8)
+
+.make_ijb:
+		stosd
+		sub [edi-2],cl			; Interrupt #
+		xchg eax,ebx
+		stosd
+		sub eax,8
+		xchg eax,ebx
+		loop .make_ijb
+
+		; Now everything is set up for interrupts...
+
+		push dword (1 << 16)		; 64K bounce buffer
+		push dword (comboot_seg << 4)	; Bounce buffer address
+		push dword com32_syscall	; Syscall entry point
+		movzx esi,word [word CmdOptPtr]
+		push esi			; Command line pointer
+		push dword 4			; Argument count
+		sti				; Interrupts OK now
+		call pm_entry			; Run the program...
+		; ... on return, fall through to com32_exit ...
+
+com32_exit:
+		mov bx,com32_done	; Return to command loop
+
+com32_enter_rm:
+		cli
+		cld
+		mov [PMESP],esp		; Save exit %esp
+		xor esp,esp		; Make sure the high bits are zero
+		jmp 08h:.in_pm16	; Return to 16-bit mode first
+
+		bits 16
+.in_pm16:
+		mov ax,18h		; Real-mode-like segment
+		mov es,ax
+		mov ds,ax
+		mov ss,ax
+		mov fs,ax
+		mov gs,ax
+
+		lidt [com32_rmidt]	; Real-mode IDT (rm needs no GDT)
+		mov eax,cr0
+		and al,~1
+		mov cr0,eax
+		jmp 0:.in_rm
+
+.in_rm:					; Back in real mode
+		mov ax,cs		; Set up sane segments
+		mov ds,ax
+		mov es,ax
+		mov fs,ax
+		mov gs,ax
+		lss sp,[SavedSSSP]	; Restore stack
+		jmp bx			; Go to whereever we need to go...
+
+com32_done:
+		call disable_a20
+		sti
+		jmp enter_command
+
+;
+; 16-bit support code
+;
+		bits 16
+
+;
+; 16-bit interrupt-handling code
+;
+com32_int_rm:
+		pushf				; Flags on stack
+		push cs				; Return segment
+		push word .cont			; Return address
+		push dword edx			; Segment:offset of IVT entry
+		retf				; Invoke IVT routine
+.cont:		; ... on resume ...
+		mov ebx,com32_int_resume
+		jmp com32_enter_pm		; Go back to PM
+
+;
+; 16-bit system call handling code
+;
+com32_sys_rm:
+		pop gs
+		pop fs
+		pop es
+		pop ds
+		popad
+		popfd
+		retf				; Invoke routine
+.return:
+		pushfd
+		pushad
+		push ds
+		push es
+		push fs
+		push gs
+		mov ebx,com32_sys_resume
+		jmp com32_enter_pm
+
+;
+; 32-bit support code
+;
+		bits 32
+
+;
+; This is invoked on getting an interrupt in protected mode.  At
+; this point, we need to context-switch to real mode and invoke
+; the interrupt routine.
+;
+; When this gets invoked, the registers are saved on the stack and
+; AL contains the register number.
+;
+com32_handle_interrupt:
+		movzx eax,al
+		xor ebx,ebx		; Actually makes the code smaller
+		mov edx,[ebx+eax*4]	; Get the segment:offset of the routine
+		mov bx,com32_int_rm
+		jmp com32_enter_rm	; Go to real mode
+
+com32_int_resume:
+		popad
+		iret
+
+;
+; Syscall invocation.  We manifest a structure on the real-mode stack,
+; containing the com32sys_t structure from <com32.h> as well as
+; the following entries (from low to high address):
+; - Target offset
+; - Target segment
+; - Return offset
+; - Return segment (== real mode cs == 0)
+; - Return flags
+;
+com32_syscall:
+		pushfd			; Save IF among other things...
+		pushad			; We only need to save some, but...
+		cld
+
+		movzx edi,word [word SavedSSSP]
+		movzx eax,word [word SavedSSSP+2]
+		sub edi,54		; Allocate 54 bytes
+		mov [word SavedSSSP],di
+		shl eax,4
+		add edi,eax		; Create linear address
+
+		mov esi,[esp+11*4]	; Source regs
+		xor ecx,ecx
+		mov cl,11		; 44 bytes to copy
+		rep movsd
+
+		movzx eax,byte [esp+10*4] ; Interrupt number
+		; ecx == 0 here; adding it to the EA makes the
+		; encoding smaller
+		mov eax,[ecx+eax*4]	; Get IVT entry
+		stosd			; Save in stack frame
+		mov eax,com32_sys_rm.return	; Return seg:offs
+		stosd			; Save in stack frame
+		mov eax,[edi-12]	; Return flags
+		and eax,0x200cd7	; Mask (potentially) unsafe flags
+		mov [edi-12],eax	; Primary flags entry
+		stosw			; Return flags
+
+		mov bx,com32_sys_rm
+		jmp com32_enter_rm	; Go to real mode
+
+		; On return, the 44-byte return structure is on the
+		; real-mode stack.
+com32_sys_resume:
+		movzx esi,word [word SavedSSSP]
+		movzx eax,word [word SavedSSSP+2]
+		mov edi,[esp+12*4]	; Dest regs
+		shl eax,4
+		add esi,eax		; Create linear address
+		and edi,edi		; NULL pointer?
+		jnz .do_copy
+.no_copy:	mov edi,esi		; Do a dummy copy-to-self
+.do_copy:	xor ecx,ecx
+		mov cl,11		; 44 bytes
+		rep movsd		; Copy register block
+
+		add dword [word SavedSSSP],44	; Remove from stack
+
+		popad
+		popfd
+		ret			; Return to 32-bit program
+
+		bits 16
diff --git a/comboot.doc b/comboot.doc
new file mode 100644
index 0000000..db9203a
--- /dev/null
+++ b/comboot.doc
@@ -0,0 +1,266 @@
+$Id$
+
+		       COMBOOT and COM32 files
+
+
+SYSLINUX supports simple standalone programs, using a file format
+similar to DOS ".com" files.  A 32-bit version, called COM32, is also
+provided.  A simple API provides access to a limited set of filesystem
+and console functions.
+
+
+	++++ COMBOOT file format ++++
+
+A COMBOOT file is a raw binary file containing 16-bit code.  It should
+be linked to run at offset 0x100, and contain no absolute segment
+references.  It is run in 16-bit real mode.
+
+A COMBOOT image can be written to be compatible with MS-DOS.  Such a
+file will usually have extension ".com".  A COMBOOT file which is not
+compatible with MS-DOS will usually have extension ".cbt".
+
+Before running the program, SYSLINUX sets up the following fields in
+the Program Segment Prefix (PSP), a structure at offset 0 in the
+program segment:
+
+ Offset	Size	Meaning
+ 0	word	Contains an INT 20h instruction
+ 2	word	Contains the paragraph (16-byte "segment" address) at
+		the end of memory available to the program.
+ 128	byte	Length of the command line arguments, including the leading
+		space but not including the final CR character.
+ 129	127b	Command line arguments, starting with a space and ending
+		with a CR character (ASCII 13).
+
+The program is allowed to use memory between the PSP paragraph (which
+all the CS, DS, ES and SS registers point to at program start) and the
+paragraph value given at offset 2.
+
+On startup, SP is set up to point to the end of the 64K segment, at
+0xfffe.  Under DOS it is possible for SP to contain a smaller
+value if memory is very tight; this is never the case under SYSLINUX.
+
+The program should make no assumptions about what segment address it
+will be loaded at; instead it should look at the segment registers on
+program startup.  Both DOS and SYSLINUX will guarantee CS == DS == ES
+== SS on program start; the program should not assume anything about
+the values of FS or GS.
+
+To exit, a program can either execute a near RET (which will jump to
+offset 0 which contains an INT 20h instruction, terminating the
+program), or execute INT 20h or INT 21h AH=00h or INT 21h AH=4Ch.
+If compatiblity with SYSLINUX 1.xx is desired, use INT 20h.
+
+
+	++++ COM32 file format ++++
+
+A COM32 file is a raw binary file containing 32-bit code.  It should
+be linked to run at address 0x101000, and should not contain any
+segment references.  It will be run in flat-memory 32-bit protected
+mode.  Under SYSLINUX, it will be run in CPL 0, however, since it may
+be possible to create a COM32 execution engine that would run under
+something like Linux DOSEMU, it is recommended that the code does not
+assume CPL 0 unless absolutely necessary.
+
+A COM32 file should have extension ".c32".
+
+On startup, CS will be set up as a flat 32-bit code segment, and DS ==
+ES == SS will be set up as the equivalent flat 32-bit data segment.
+FS and GS are reserved for future use and are currently initialized to
+zero.  A COM32 image should not assume any particular values of
+segment selectors.
+
+ESP is set up at the end of available memory and also serves as
+notification to the program how much memory is available.
+
+The following arguments are passed to the program on the stack:
+
+ Address  Size	Meaning
+ [ESP+4]  dword	Number of additional arguments (currently 4)
+ [ESP+8]  dword	Pointer to the command line arguments (null-terminated string)
+ [ESP+12] dword Pointer to system call helper function
+ [ESP+16] dword Pointer to low memory bounce buffer
+ [ESP+20] dword Size of low memory bounce buffer
+
+This corresponds to the following C prototype, available in the file com32.h:
+
+/* The standard prototype for _start() */
+int _start(unsigned int __nargs,
+	   char *__cmdline,
+	   void (*__syscall)(unsigned char, com32sys_t *, com32sys_t *),
+	   void *__bounce_ptr,
+	   unsigned int __bounce_len);
+
+The system call helper function can be used to issue BIOS or SYSLINUX
+API calls, and takes the interrupt number as first argument.  The
+second argument is a pointer to the input register definition, an
+instance of the following structure (also available in com32.h):
+
+typedef struct {
+  unsigned short gs;		/* Offset  0 */
+  unsigned short fs;		/* Offset  2 */
+  unsigned short es;		/* Offset  4 */
+  unsigned short ds;		/* Offset  6 */
+
+  unsigned int edi;		/* Offset  8 */
+  unsigned int esi;		/* Offset 12 */
+  unsigned int ebp;		/* Offset 16 */
+  unsigned int _unused;		/* Offset 20 */
+  unsigned int ebx;		/* Offset 24 */
+  unsigned int edx;		/* Offset 28 */
+  unsigned int ecx;		/* Offset 32 */
+  unsigned int eax;		/* Offset 36 */
+
+  unsigned int eflags;		/* Offset 40 */
+} com32sys_t;
+
+The third argument is a pointer to the output register definition, an
+instance of the same structure.  The third argument can also be zero
+(NULL).
+
+Since BIOS or SYSLINUX API calls can generally only manipulate data
+below address 0x100000, a "bounce buffer" in low memory, at least 64K
+in size, is available, to copy data in and out.
+
+
+	++++ SYSLINUX API CALLS +++
+
+SYSLINUX provides the following API calls.  SYSLINUX 1.xx only
+supported INT 20h - terminate program.
+
+
+	++++ DOS-COMPATIBLE API CALLS ++++
+
+INT 20h:	Terminate program
+INT 21h AH=00h	Terminate program
+
+	++++ SYSLINUX-SPECIFIC API CALLS ++++
+
+SYSLINUX-specific API calls are executed using INT 22h, with a
+function number in AX.  INT 22h is used by DOS for internal purposes;
+do not execute INT 22h under DOS.
+
+DOS-compatible function INT 21h, AH=30h can be used to detect if the
+SYSLINUX API calls are available.
+
+All INT 22h API calls may clobber the general-purpose registers (EAX,
+EBX, ECX, EDX, EBP, ESI and EDI).  Segment registers are left
+unchanged unless otherwise noted.
+
+All calls return CF=0 on success, CF=1 on failure.  The noted outputs
+apply if CF=0 only unless otherwise noted.
+
+
+AX=0000h	No Operation
+
+	Input:	AX	0000h
+	Output:	None
+
+	This API call does nothing.
+
+
+AX=0001h	Get Version
+
+	Input:	AX	0001h
+	Output:	AX	number of INT 22h API functions available
+		CH 	SYSLINUX major version number
+		CL 	SYSLINUX minor version number
+		DL 	SYSLINUX derivative ID (e.g. 32h = PXELINUX)
+		ES:SI	SYSLINUX version string
+		ES:DI 	SYSLINUX copyright string
+
+	This API call returns the SYSLINUX version and API
+	information.
+
+
+AX=0002h	Write String
+
+	Input:	AX	0002h
+		ES:BX	null-terminated string
+	Output:	None
+
+	Writes a null-terminated string on the console.
+
+
+AX=0003h	Run command
+
+	Input:	AX	0003h
+		ES:BX	null-terminated command string
+	Output:	None
+
+	This API call terminates the program and executes the command
+	string as if the user had entered it at the SYSLINUX command
+	line.  This API call does not return.
+
+
+AX=0004h	Run default command
+
+	Input:	AX	0004h
+	Output:	None
+
+	This API call terminates the program and executes the default
+	command string as if the user had pressed Enter alone on the
+	SYSLINUX command line.  This API call does not return.
+
+
+AX=0005h	Force text mode
+
+	Input:	AX	0005h
+	Output:	None
+
+	If the screen was in graphics mode (due to displaying a splash
+	screen using the <Ctrl-X> command in a message file, or
+	similar), return to text mode.
+
+
+AX=0006h	Open file
+
+	Input:	AX	0006h
+		ES:SI	null-terminated filename
+	Output:	SI	file handle
+		EAX	length of file in bytes
+		CX	file block size
+
+	Open a file for reading.  The exact syntax of the filenames
+	allowed depends on the particular SYSLINUX derivative.
+
+	The SYSLINUX file system is block-oriented.  The size of a
+	block will always be a power of two and no greater than 16K.
+
+	Note: SYSLINUX considers a zero-length file to be nonexistent.
+
+
+AX=0007h	Read file
+
+	Input:	AX	0007h
+		SI	file handle
+		ES:BX	buffer
+		CX	number of blocks to read
+	Output:	SI	file handle, or 0 if EOF was reached
+
+	Read blocks from a file.  Note that the file handle that is
+	returned in SI may not be the same value that was passed in.
+
+	If end of file was reached (SI=0), the file was automatically
+	closed.
+
+	The address of the buffer (ES:BX) should be at least 512-byte
+	aligned.  SYSLINUX guarantees at least this alignment for the
+	COMBOOT load segment or the COM32 bounce buffer.
+
+	WARNING: Calling this function with an invalid file handle
+	will probably crash the system.
+
+
+AX=0008h	Close file
+
+	Input:	AX	0008h
+		SI	file handle
+	Output:	None
+
+	Close a file before reaching the end of file.
+
+	WARNING: Calling this function with an invalid file handle
+	will probably crash the system.
+
+
diff --git a/comboot.inc b/comboot.inc
index 5d7019e..319e500 100644
--- a/comboot.inc
+++ b/comboot.inc
@@ -21,7 +21,7 @@
 comboot_too_large:
 		mov si,err_comlarge
 		call cwritestr
-cb_enter:	jmp enter_command
+		jmp enter_command
 
 ;
 ; Load a COMBOOT image.  A COMBOOT image is basically a DOS .COM file,
@@ -34,17 +34,7 @@ is_comboot_image:
 		cmp ax,0ff00h		; Max size in bytes
 		jae comboot_too_large
 
-		;
-		; Set up the DOS vectors in the IVT (INT 20h-3fh)
-		;
-		mov di,4*0x20		; DOS interrupt vectors
-		mov eax,comboot_return
-		stosd
-		mov ax,comboot_int21
-		stosd
-		mov ax,comboot_bogus
-		mov cx,30		; All remaining DOS vectors
-		rep stosd
+		call comboot_setup_api
 
 		mov cx,comboot_seg
 		mov es,cx
@@ -84,8 +74,6 @@ comboot_end_cmd: mov al,0Dh		; CR after last character
 		mov [SavedSSSP],sp
 		mov [SavedSSSP+2],ss	; Save away SS:SP
 
-		call vgaclearmode	; Reset video
-
 		mov ax,es
 		mov ds,ax
 		mov ss,ax
@@ -99,9 +87,40 @@ comboot_return:	cli			; Don't trust anyone
 		xor ax,ax
 		jmp comboot_exit
 
+;
+; Set up the COMBOOT API interrupt vectors.  This is also used
+; by the COM32 code.
+;
+comboot_setup_api:
+		mov di,4*0x20		; DOS interrupt vectors
+		mov eax,comboot_return	; INT 20h = exit
+		stosd
+		mov ax,comboot_int21	; INT 21h = DOS-compatible syscalls
+		stosd
+		mov ax,comboot_int22	; INT 22h = proprietary syscalls
+		stosd
+		mov ax,comboot_bogus
+		mov cx,29		; All remaining DOS vectors
+		rep stosd
+		ret
+
 ; INT 21h: generic DOS system call
-comboot_int21:	and ah,ah		; 00 = return
+comboot_int21:	push ds
+		push cs
+		pop ds			; Set DS <- CS
+		and ah,ah		; 00 = return
 		je comboot_return
+		cmp ah,02h
+		jb comboot_getkeyecho	; 01 = get key with echo
+		je comboot_writechr	; 02 = writechr
+		cmp ah,08h		; 08 = get key w/o echo
+		je comboot_getkey
+		cmp ah,09h		; 09 = writestr
+		je comboot_writestr
+		cmp ah,0Bh		; 0B = check keyboard
+		je comboot_checkkey
+		cmp ah,30h		; 30 = check version
+		je comboot_checkver
 		cmp ah,4Ch		; 4C = return with status
 		je comboot_return
 
@@ -110,15 +129,18 @@ comboot_int21:	and ah,ah		; 00 = return
 ; Attempted to execute non-21h DOS system call
 comboot_bogus:	cli			; Don't trust anyone
 		mov ax,err_notdos
-
 ;
 ; Generic COMBOOT return to command line code
+;  AX -> message (if any)
+;  BX -> where to go next
 ;
 comboot_exit:
-		lss sp,[cs:SavedSSSP]
+		mov bx,enter_command	; Normal return to command prompt
+comboot_exit_special:
 		xor dx,dx
 		mov ds,dx
 		mov es,dx
+		lss sp,[SavedSSSP]
 		sti
 		cld
 		and ax,ax
@@ -127,5 +149,224 @@ comboot_exit:
 		call cwritestr
 		xchg si,ax
 		call cwritestr
-.nomsg:		jmp cb_enter
+.nomsg:		jmp bx
+
+;
+; INT 21h system calls
+;
+comboot_getkeyecho:			; 01 = get key with echo
+		call vgashowcursor
+		call getchar
+		call vgahidecursor
+		call writechr
+		jmp comboot_resume_ok
+
+comboot_writechr:			; 02 = writechr
+		xchg ax,dx
+		call writechr
+		xchg ax,dx
+		jmp comboot_resume_ok
+
+comboot_getkey:				; 08 = get key w/o echo
+		call vgashowcursor
+		call getchar
+		call vgahidecursor
+		jmp comboot_resume_ok
+
+comboot_writestr:			; 09 = write string
+		pusha
+		push es
+		mov bp,sp
+		mov es,[bp-20]		; Old DS
+		mov si,dx
+.loop:		es lodsb
+		cmp al,'$'		; End string with $ - bizarre
+		je .done
+		call writechr
+		jmp short .loop
+.done:		pop es
+		popa
+		jmp comboot_resume_ok
+
+comboot_checkkey:			; 0B = check keyboard status
+		call pollchar
+		setz al
+		dec al			; AL = 0FFh if present, 0 if not
+		jmp comboot_resume_ok
+
+comboot_checkver:			; 30 = check DOS version
+		; We return 0 in all DOS-compatible version registers,
+		; but the high part of eax-ebx-ecx-edx spell "SYSLINUX"
+		mov eax,'SY' << 16
+		mov ebx,'SL' << 16
+		mov ecx,'IN' << 16
+		mov edx,'UX' << 16
+		;jmp comboot_resume_ok
+
+;
+; Resume comboot execution
+;
+comboot_resume_ok:
+		clc
+comboot_resume:
+		pop ds
+		iret
+
+comboot_apierr:
+		stc
+		jmp comboot_resume
+
+;
+; INT 22h - SYSLINUX-specific system calls
+;           System call number in ax
+;
+comboot_int22:
+		push ds
+		push cs
+		pop ds
+
+		cmp ax,int22_count
+		jae comboot_apierr
+
+		xchg ax,bx
+		add bx,bx
+		call [bx+int22_table]
+		jmp comboot_resume		; On return
+
+;
+; INT 22h AX=0000h	Null system call
+; INT 22h AX=0001h	Get SYSLINUX version
+;
+comapi_get_version:
+		; Number of API functions supported
+		mov ax,int22_count
+		; SYSLINUX version
+		mov cx,(VER_MAJOR << 8)+VER_MINOR
+		; SYSLINUX derivative ID byte
+		mov dx,my_id
+		; For future use
+		xor bx,bx
+
+		push cs
+		pop es
+		; ES:SI -> version banner
+		mov si,syslinux_banner
+		; ES:DI -> copyright string
+		mov di,copyright_str
+
+comapi_nop:
+		clc
+		ret
+
+;
+; INT 22h AX=0002h	Write string
+;
+; Write null-terminated string in ES:BX
+;
+comapi_writestr:
+		push es
+		pop ds
+		mov si,ax
+		jmp writestr			; Write string from ES:BX
+
+;
+; INT 22h AX=0003h	Run command
+;
+; Terminates the COMBOOT program and executes the command line in
+; ES:BX as if it had been entered by the user.
+;
+comapi_run:
+		push es
+		push ds
+		pop es
+		pop ds
+		mov si,ax
+		mov di,command_line
+.copyloop:
+		lodsb
+		stosb
+		and al,al
+		jnz .copyloop
+		xor ax,ax
+		mov bx,load_kernel		; Run a new kernel
+		jmp comboot_exit_special	; Terminate task, clean up
+
+;
+; INT 22h AX=0004h	Run default command		
+;
+; Terminates the COMBOOT program and executes the default command line
+; as if a timeout had happened or the user pressed <Enter>.
+;
+comapi_run_default:
+		mov bx,auto_boot
+		jmp comboot_exit_special
+
+;
+; INT 22h AX=0005h	Force text mode
+;
+; Puts the video in standard text mode
+;
+comapi_textmode:
+		call vgaclearmode
+		clc
+		ret
+
+;
+; INT 22h AX=0006h	Open file
+;
+comapi_open:
+		push ds
+		push ds
+		push es
+		pop ds
+		pop es
+		mov di,InitRD
+		push di
+		call mangle_name
+		pop di
+		pop ds
+		call searchdir
+		jz .err
+		xchg eax,edx
+		shr eax,16
+		xchg ax,dx
+		mov cx,[SecPerClust]
+		clc
+		ret
+.err:
+		stc
+		ret
+
+
+;
+; INT 22h AX=0007h	Read file
+;
+comapi_read:
+		xchg ax,bx
+		call getfssec
+		jnc .noteof
+		xor si,si		; SI <- 0 on EOF, CF <- 0
+.noteof:	ret
+
+;
+; INT 22h AX=0008h	Close file
+;
+comapi_close:
+		; Do nothing for now.  Eventually implement
+		; an internal API for this.
+		clc
+		ret
+
 
+		align 2, db 0
+int22_table:
+		dw comapi_nop			; 0000 null syscall
+		dw comapi_get_version		; 0001 get SYSLINUX version
+		dw comapi_writestr		; 0002 write string
+		dw comapi_run			; 0003 run specified command
+		dw comapi_run_default		; 0004 run default command
+		dw comapi_textmode		; 0005 force text mode
+		dw comapi_open			; 0006 open file
+		dw comapi_read			; 0007 read file
+		dw comapi_close			; 0008 close file
+int22_count	equ ($-int22_table)/2
diff --git a/config.inc b/config.inc
index 3282d5b..52a1846 100644
--- a/config.inc
+++ b/config.inc
@@ -28,6 +28,13 @@ BAUD_DIVISOR	equ 115200		; Serial port parameter
 %assign	DO_WBINVD 0			; Should we use WBINVD or not?
 
 ;
+; Version number definitinons
+;
+%ifndef DEPEND				; Generated file
+%include "version.gen"
+%endif
+
+;
 ; Should be updated with every release to avoid bootsector/SYS file mismatch
 ;
 %define	version_str	VERSION		; Must be 4 characters long!
diff --git a/conio.inc b/conio.inc
index 5850b9d..7dc1572 100644
--- a/conio.inc
+++ b/conio.inc
@@ -158,7 +158,7 @@ msg_formfeed:                                   ; Form feed character
                 mov bh,[TextAttribute]
                 mov ax,0600h                    ; Clear screen region
                 int 10h
-                jmp short msg_gotoxy
+                jmp msg_gotoxy
 msg_setbg:                                      ; Color background character
                 call unhexchar
                 jc msg_color_bad
diff --git a/cpuinit.inc b/cpuinit.inc
index a6923b5..b63ae64 100644
--- a/cpuinit.inc
+++ b/cpuinit.inc
@@ -17,49 +17,13 @@
 ;; CPU-dependent initialization and related checks.
 ;;
 
-;
-; Check that no moron is trying to boot Linux on a 286 or so.  According
-; to Intel, the way to check is to see if the high 4 bits of the FLAGS
-; register are either all stuck at 1 (8086/8088) or all stuck at 0
-; (286 in real mode), if not it is a 386 or higher.  They didn't
-; say how to check for a 186/188, so I *hope* it falls out as a 8086
-; or 286 in this test.
-;
-; Also, provide an escape route in case it doesn't work.
-;
 check_escapes:
 		mov ah,02h			; Check keyboard flags
 		int 16h
 		mov [KbdFlags],al		; Save for boot prompt check
 		test al,04h			; Ctrl->skip 386 check
 		jnz skip_checks
-test_8086:
-		pushf				; Get flags
-		pop ax
-		and ax,0FFFh			; Clear top 4 bits
-		push ax				; Load into FLAGS
-		popf
-		pushf				; And load back
-		pop ax
-		and ax,0F000h			; Get top 4 bits
-		cmp ax,0F000h			; If set -> 8086/8088
-		je not_386
-test_286:
-		pushf				; Get flags
-		pop ax
-		or ax,0F000h			; Set top 4 bits
-		push ax
-		popf
-		pushf
-		pop ax
-		and ax,0F000h			; Get top 4 bits
-		jnz is_386			; If not clear -> 386
-not_386:
-		mov si,err_not386
-		call writestr
-		jmp kaboom
-is_386:
-		; Now we know it's a 386 or higher
+
 ;
 ; Now check that there is sufficient low (DOS) memory
 ;
diff --git a/highmem.inc b/highmem.inc
new file mode 100644
index 0000000..e3a830b
--- /dev/null
+++ b/highmem.inc
@@ -0,0 +1,107 @@
+;; $Id$
+;; -----------------------------------------------------------------------
+;;   
+;;   Copyright 1994-2002 H. Peter Anvin - All Rights Reserved
+;;
+;;   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., 53 Temple Place Ste 330,
+;;   Bostom MA 02111-1307, USA; either version 2 of the License, or
+;;   (at your option) any later version; incorporated herein by reference.
+;;
+;; -----------------------------------------------------------------------
+
+;;
+;; highmem.inc
+;; 
+;; Probe for the size of high memory.  This can be overridden by a
+;; mem= command on the command line while booting a new kernel.
+;;
+
+;
+; This is set up as a subroutine; it will set up the global variable
+; HighMemSize.  All registers are preserved.  Assumes DS == CS.
+;
+highmemsize:
+		push es
+		pushad
+
+;
+; First, try INT 15:E820 (get BIOS memory map)
+;
+get_e820:
+		xor ebx,ebx			; Start with first record
+		mov es,bx			; Need ES = DS = 0 for now
+		jmp short .do_e820		; Skip "at end" check first time!
+.int_loop:	and ebx,ebx			; If we're back at beginning...
+		jz no_e820			; ... bail; nothing found
+.do_e820:	mov eax,0000E820h
+		mov edx,534D4150h		; "SMAP" backwards
+		xor ecx,ecx
+		mov cl,20			; ECX <- 20
+		mov di,E820Buf
+		int 15h
+		jc no_e820
+		cmp eax,534D4150h
+		jne no_e820
+;
+; Look for a memory block starting at <= 1 MB and continuing upward
+;
+		cmp dword [E820Buf+4], byte 0
+		ja .int_loop			; Start >= 4 GB?
+		mov edx, (1 << 20)
+		sub edx, [E820Buf]
+		jb .int_loop			; Start >= 1 MB?
+		stc
+		sbb eax,eax			; eax <- 0xFFFFFFFF
+		cmp dword [E820Buf+12], byte 0
+		ja .huge			; Size >= 4 GB
+		mov eax, [E820Buf+8]
+.huge:		sub eax, edx			; Adjust size to start at 1 MB
+		jbe .int_loop			; Completely below 1 MB?
+
+		; Now EAX contains the size of memory 1 MB...up
+		cmp dword [E820Buf+16], byte 1
+		jne near err_nohighmem		; High memory isn't usable memory!!!!
+
+		; We're good!
+		jmp short got_highmem_add1mb	; Still need to add low 1 MB
+
+;
+; INT 15:E820 failed.  Try INT 15:E801.
+;
+no_e820:
+		mov ax,0e801h			; Query high memory (semi-recent)
+		int 15h
+		jc no_e801
+		cmp ax,3c00h
+		ja no_e801			; > 3C00h something's wrong with this call
+		jb e801_hole			; If memory hole we can only use low part
+
+		mov ax,bx
+		shl eax,16			; 64K chunks
+		add eax,(16 << 20)		; Add first 16M
+		jmp short got_highmem				
+
+;
+; INT 15:E801 failed.  Try INT 15:88.
+;
+no_e801:
+		mov ah,88h			; Query high memory (oldest)
+		int 15h
+		cmp ax,14*1024			; Don't trust memory >15M
+		jna e801_hole
+		mov ax,14*1024
+e801_hole:
+		and eax,0ffffh
+		shl eax,10			; Convert from kilobytes
+got_highmem_add1mb:
+		add eax,(1 << 20)		; First megabyte
+got_highmem:
+%if HIGHMEM_SLOP != 0
+		sub eax,HIGHMEM_SLOP
+%endif
+		mov [HighMemSize],eax
+		popad
+		pop es
+		ret				; Done!
diff --git a/isolinux.asm b/isolinux.asm
index 6c84773..5d5e418 100644
--- a/isolinux.asm
+++ b/isolinux.asm
@@ -145,6 +145,7 @@ HighMemSize	resd 1			; End of memory pointer (bytes)
 RamdiskMax	resd 1			; Highest address for a ramdisk
 KernelSize	resd 1			; Size of kernel (bytes)
 SavedSSSP	resd 1			; Our SS:SP while running a COMBOOT image
+PMESP		resd 1			; Protected-mode ESP
 RootDir		resb dir_t_size		; Root directory
 CurDir		resb dir_t_size		; Current directory
 KernelClust	resd 1			; Kernel size in clusters
@@ -1163,6 +1164,7 @@ kernel_corrupt: mov si,err_notkernel
 ;
 ; .com 	- COMBOOT image
 ; .cbt	- COMBOOT image
+; .c32  - COM32 image
 ; .bs	- Boot sector
 ; .0	- PXE bootstrap program (PXELINUX only)
 ; .bin  - Boot sector
@@ -1202,6 +1204,8 @@ kernel_good:
 		je is_comboot_image
 		cmp ecx,'.cbt'
 		je is_comboot_image
+		cmp ecx,'.c32'
+		je is_com32_image
 		cmp ecx,'.img'
 		je is_disk_image
 		cmp ecx,'.bss'
@@ -1225,6 +1229,7 @@ kernel_good:
 ; COMBOOT-loading code
 ;
 %include "comboot.inc"
+%include "com32.inc"
 
 ;
 ; Boot sector loading code
@@ -1845,6 +1850,7 @@ getfssec:
 %include "loadhigh.inc"		; Load a file into high memory
 %include "font.inc"		; VGA font stuff
 %include "graphics.inc"		; VGA graphics
+%include "highmem.inc"		; High memory sizing
 
 ; -----------------------------------------------------------------------------
 ;  Begin data section
@@ -1859,15 +1865,6 @@ boot_prompt	db 'boot: ', 0
 wipe_char	db BS, ' ', BS, 0
 err_notfound	db 'Could not find kernel image: ',0
 err_notkernel	db CR, LF, 'Invalid or corrupt kernel image.', CR, LF, 0
-err_not386	db 'It appears your computer uses a 286 or lower CPU.'
-		db CR, LF
-		db 'You cannot run Linux unless you have a 386 or higher CPU'
-		db CR, LF
-		db 'in your machine.  If you get this message in error, hold'
-		db CR, LF
-		db 'down the Ctrl key while booting, and I will take your'
-		db CR, LF
-		db 'word for it.', CR, LF, 0
 err_noram	db 'It appears your computer has less than 360K of low ("DOS")'
 		db 0Dh, 0Ah
 		db 'RAM.  Linux needs at least this amount to boot.  If you get'
diff --git a/ldlinux.asm b/ldlinux.asm
index bf8ebbc..f35deb6 100644
--- a/ldlinux.asm
+++ b/ldlinux.asm
@@ -139,6 +139,7 @@ HighMemSize	resd 1			; End of memory pointer (bytes)
 RamdiskMax	resd 1			; Highest address for a ramdisk
 KernelSize	resd 1			; Size of kernel (bytes)
 SavedSSSP	resd 1			; Our SS:SP while running a COMBOOT image
+PMESP		resd 1			; Protected-mode ESP
 ClustPerMoby	resd 1			; Clusters per 64K
 ClustSize	resd 1			; Bytes/cluster
 KernelName      resb 12		        ; Mangled name for kernel
@@ -793,7 +794,8 @@ all_read_jmp:
 ;	SI	-> Starting cluster number (2-based)
 ;	CX	-> Cluster count (0FFFFh = until end of file)
 ;
-						; 386 check
+;	Returns CF=1 on EOF
+;
 getfssec:
 getfragment:	xor ebp,ebp			; Fragment sector count
 		movzx eax,si			; Get sector address
@@ -1311,6 +1313,7 @@ kernel_corrupt: mov si,err_notkernel
 ;
 ; .com 	- COMBOOT image
 ; .cbt	- COMBOOT image
+; .c32  - COM32 image
 ; .bs	- Boot sector
 ; .0	- PXE bootstrap program (PXELINUX only)
 ; .bin  - Boot sector
@@ -1334,6 +1337,8 @@ kernel_good:
 		je is_comboot_image
 		cmp ecx,'CBT'
 		je is_comboot_image
+		cmp ecx,'C32'
+		je is_com32_image
 		cmp ecx,'BS '
 		je is_bootsector
 		cmp ecx,'BIN'
@@ -1351,6 +1356,7 @@ kernel_good:
 ; COMBOOT-loading code
 ;
 %include "comboot.inc"
+%include "com32.inc"
 
 ;
 ; Boot sector loading code
@@ -1625,6 +1631,7 @@ lc_ret:         ret
 %include "loadhigh.inc"		; Load a file into high memory
 %include "font.inc"		; VGA font stuff
 %include "graphics.inc"		; VGA graphics
+%include "highmem.inc"		; High memory sizing
 
 ; -----------------------------------------------------------------------------
 ;  Begin data section
@@ -1651,15 +1658,6 @@ boot_prompt	db 'boot: ', 0
 wipe_char	db BS, ' ', BS, 0
 err_notfound	db 'Could not find kernel image: ',0
 err_notkernel	db CR, LF, 'Invalid or corrupt kernel image.', CR, LF, 0
-err_not386	db 'It appears your computer uses a 286 or lower CPU.'
-		db CR, LF
-		db 'You cannot run Linux unless you have a 386 or higher CPU'
-		db CR, LF
-		db 'in your machine.  If you get this message in error, hold'
-		db CR, LF
-		db 'down the Ctrl key while booting, and I will take your'
-		db CR, LF
-		db 'word for it.', CR, LF, 0
 err_noram	db 'It appears your computer has less than 488K of low ("DOS")'
 		db CR, LF
 		db 'RAM.  Linux needs at least this amount to boot.  If you get'
diff --git a/pxelinux.asm b/pxelinux.asm
index bb08d6e..67894fa 100644
--- a/pxelinux.asm
+++ b/pxelinux.asm
@@ -193,6 +193,7 @@ HighMemSize	resd 1			; End of memory pointer (bytes)
 RamdiskMax	resd 1			; Highest address for a ramdisk
 KernelSize	resd 1			; Size of kernel (bytes)
 SavedSSSP	resd 1			; Our SS:SP while running a COMBOOT image
+PMESP		resd 1			; Protected-mode ESP
 Stack		resd 1			; Pointer to reset stack
 PXEEntry	resd 1			; !PXE API entry point
 RebootTime	resd 1			; Reboot timeout, if set by option
@@ -1037,6 +1038,7 @@ kernel_corrupt: mov si,err_notkernel
 ;
 ; .com 	- COMBOOT image
 ; .cbt	- COMBOOT image
+; .c32  - COM32 image
 ; .bs	- Boot sector
 ; .0	- PXE bootstrap program (PXELINUX only)
 ; .bin  - Boot sector
@@ -1078,6 +1080,8 @@ kernel_good:
 		je is_comboot_image
 		cmp ecx,'.cbt'
 		je is_comboot_image
+		cmp ecx,'.c32'
+		je is_com32_image
 		cmp ecx,'.bss'
 		je is_bss_image
 		cmp ecx,'.bin'
@@ -1124,6 +1128,7 @@ kernel_good:
 ; COMBOOT-loading code
 ;
 %include "comboot.inc"
+%include "com32.inc"
 
 ;
 ; Boot sector loading code
@@ -2099,21 +2104,21 @@ parse_dhcp_options:
 		jne .not_subnet
 		mov edx,[si]
 		mov [Netmask],edx
-		jmp short .opt_done
+		jmp .opt_done
 .not_subnet:
 
 		cmp dl,3	; ROUTER option
 		jne .not_router
 		mov edx,[si]
 		mov [Gateway],edx
-		jmp short .opt_done
+		jmp .opt_done
 .not_router:
 
 		cmp dl,52	; OPTION OVERLOAD option
 		jne .not_overload
 		mov dl,[si]
 		mov [OverLoad],dl
-		jmp short .opt_done
+		jmp .opt_done
 .not_overload:
 
 		cmp dl,67	; BOOTFILE NAME option
@@ -2222,6 +2227,7 @@ writestr	equ cwritestr
 %include "loadhigh.inc"		; Load a file into high memory
 %include "font.inc"		; VGA font stuff
 %include "graphics.inc"		; VGA graphics
+%include "highmem.inc"		; High memory sizing
 
 ; -----------------------------------------------------------------------------
 ;  Begin data section
@@ -2238,15 +2244,6 @@ boot_prompt	db 'boot: ', 0
 wipe_char	db BS, ' ', BS, 0
 err_notfound	db 'Could not find kernel image: ',0
 err_notkernel	db CR, LF, 'Invalid or corrupt kernel image.', CR, LF, 0
-err_not386	db 'It appears your computer uses a 286 or lower CPU.'
-		db CR, LF
-		db 'You cannot run Linux unless you have a 386 or higher CPU'
-		db CR, LF
-		db 'in your machine.  If you get this message in error, hold'
-		db CR, LF
-		db 'down the Ctrl key while booting, and I will take your'
-		db CR, LF
-		db 'word for it.', CR, LF, 0
 err_noram	db 'It appears your computer has less than 384K of low ("DOS")'
 		db 0Dh, 0Ah
 		db 'RAM.  Linux needs at least this amount to boot.  If you get'
diff --git a/runkernel.inc b/runkernel.inc
index eabb792..3ee28f9 100644
--- a/runkernel.inc
+++ b/runkernel.inc
@@ -96,89 +96,15 @@ kernel_sane:	push ax
 		call getfssec
                 cmp word [es:bs_bootsign],0AA55h
 		jne kernel_corrupt		; Boot sec signature missing
-;
-; Get the BIOS' idea of what the size of high memory is.
-;
-		push si				; Save our cluster pointer!
-;
-; First, try INT 15:E820 (get BIOS memory map)
-;
-get_e820:
-		push es
-		xor ebx,ebx			; Start with first record
-		mov es,bx			; Need ES = DS = 0 for now
-		jmp short .do_e820		; Skip "at end" check first time!
-.int_loop:	and ebx,ebx			; If we're back at beginning...
-		jz no_e820			; ... bail; nothing found
-.do_e820:	mov eax,0000E820h
-		mov edx,534D4150h		; "SMAP" backwards
-		mov ecx,20
-		mov di,E820Buf
-		int 15h
-		jc no_e820
-		cmp eax,534D4150h
-		jne no_e820
-;
-; Look for a memory block starting at <= 1 MB and continuing upward
-;
-		cmp dword [E820Buf+4], byte 0
-		ja .int_loop			; Start >= 4 GB?
-		mov edx, (1 << 20)
-		sub edx, [E820Buf]
-		jb .int_loop			; Start >= 1 MB?
-		stc
-		sbb eax,eax			; eax <- 0xFFFFFFFF
-		cmp dword [E820Buf+12], byte 0
-		ja .huge			; Size >= 4 GB
-		mov eax, [E820Buf+8]
-.huge:		sub eax, edx			; Adjust size to start at 1 MB
-		jbe .int_loop			; Completely below 1 MB?
-
-		; Now EAX contains the size of memory 1 MB...up
-		cmp dword [E820Buf+16], byte 1
-		jne err_nohighmem		; High memory isn't usable memory!!!!
-
-		; We're good!
-		pop es
-		jmp short got_highmem_add1mb	; Still need to add low 1 MB
 
 ;
-; INT 15:E820 failed.  Try INT 15:E801.
+; Save the cluster pointer for later...
 ;
-no_e820:	pop es
-
-		mov ax,0e801h			; Query high memory (semi-recent)
-		int 15h
-		jc no_e801
-		cmp ax,3c00h
-		ja no_e801			; > 3C00h something's wrong with this call
-		jb e801_hole			; If memory hole we can only use low part
-
-		mov ax,bx
-		shl eax,16			; 64K chunks
-		add eax,(16 << 20)		; Add first 16M
-		jmp short got_highmem				
-
+		push si
 ;
-; INT 15:E801 failed.  Try INT 15:88.
+; Get the BIOS' idea of what the size of high memory is.
 ;
-no_e801:
-		mov ah,88h			; Query high memory (oldest)
-		int 15h
-		cmp ax,14*1024			; Don't trust memory >15M
-		jna e801_hole
-		mov ax,14*1024
-e801_hole:
-		and eax,0ffffh
-		shl eax,10			; Convert from kilobytes
-got_highmem_add1mb:
-		add eax,(1 << 20)		; First megabyte
-got_highmem:
-%if HIGHMEM_SLOP != 0
-		sub eax,HIGHMEM_SLOP
-%endif
-		mov [HighMemSize],eax
-
+		call highmemsize
 ;
 ; Construct the command line (append options have already been copied)
 ;
diff --git a/sample/Makefile b/sample/Makefile
index f4ad1bc..e6b648a 100644
--- a/sample/Makefile
+++ b/sample/Makefile
@@ -15,15 +15,31 @@
 ## samples for syslinux users
 ##
 
+CC         = gcc
+LD         = ld
+CFLAGS     = -O2 -fomit-frame-pointer -I..
+LDFLAGS    = -s
+OBJCOPY    = objcopy
 PPMTOLSS16 = 	../ppmtolss16
 
-all: syslogo.lss
+.SUFFIXES: .lss .c .o .elf .c32
+
+all: syslogo.lss hello.c32
+
+.c.o:
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+.elf.c32:
+	$(OBJCOPY) -O binary $< $@
 
 syslogo.lss:	syslogo.png $(PPMTOLSS16)
 	pngtopnm syslogo.png | \
 		$(PPMTOLSS16) \#000000=0 \#d0d0d0=7 \#f6f6f6=15	\
 		> syslogo.lss
 
+hello.elf: hello.o
+	$(LD) -Ttext 0x101000 -e _start -o $@ $<
+
 clean:
 	rm -f *.lss
 
diff --git a/sample/hello.c b/sample/hello.c
new file mode 100644
index 0000000..194092e
--- /dev/null
+++ b/sample/hello.c
@@ -0,0 +1,47 @@
+#ident "$Id$"
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2002 H. Peter Anvin - All Rights Reserved
+ *
+ *   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., 53 Temple Place Ste 330,
+ *   Bostom MA 02111-1307, USA; either version 2 of the License, or
+ *   (at your option) any later version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * hello.c
+ *
+ * Simple COM32 image
+ */
+
+#include <com32.h>
+
+#define NULL ((void *)0)
+
+static inline void memset(void *buf, int ch, unsigned int len)
+{
+  asm volatile("cld; rep; stosb"
+	       : "+D" (buf), "+c" (len) : "a" (ch) : "memory");
+}
+
+int _start(unsigned int nargs, char *cmdline,
+	   void (*syscall)(unsigned char, com32sys_t *, com32sys_t *),
+	   void *bounce_ptr, unsigned int bounce_len)
+{
+  const char *msg = "Hello, World!\r\n";
+  com32sys_t inreg, outreg;
+  const char *p;
+
+  memset(&inreg, 0, sizeof inreg);
+
+  for ( p = msg ; *p ; p++ ) {
+    inreg.edx = *p;
+    inreg.eax = 0x0200;
+    syscall(0x21, &inreg, NULL);
+  }
+
+  return 0;
+}
diff --git a/version b/version
index 07cde98..2888737 100644
--- a/version
+++ b/version
@@ -1 +1 @@
-1.75
+2.00
diff --git a/version.pl b/version.pl
new file mode 100755
index 0000000..fa09e40
--- /dev/null
+++ b/version.pl
@@ -0,0 +1,25 @@
+#!/usr/bin/perl
+#
+# Read the "version" file and produce some macro declarations
+#
+
+use Fcntl;
+
+$vfile = $ARGV[0];
+sysopen(VERSION, $vfile, O_RDONLY) or die "$0: Cannot open $vfile\n";
+$version = <VERSION>;
+chomp $version;
+close(VERSION);
+
+unless ( $version =~ /^([0-9]+)\.([0-9]+)$/ ) {
+    die "$0: Cannot parse version format\n";
+}
+$vma = $1+0; $vmi = $2+0;
+
+open(VI, "> version.gen") or die "$0: Cannot create version.gen\n";
+print VI "%define VERSION \"$version\"\n";
+print VI "%define VER_MAJOR $vma\n";
+print VI "%define VER_MINOR $vmi\n";
+close(VI);
+
+