Add a bootstrap chainloading API, and include a sample program for it.syslinux-2.08-pre5

9 files changed, 177 insertions, 38 deletions

diff --git a/NEWS b/NEWS
index 236ba35d..d4e31a3a 100644
--- a/NEWS
+++ b/NEWS
@@ -13,6 +13,9 @@ Changes in 2.08:
 	  (including file not found.)  This bug would cause us to run
 	  out of sockets and thus "go deaf" after a while.
 	* MEMDISK: Add an API to query for the existence of MEMDISK.
+	* SYSLINUX: Fix loading boot sectors (.bs/.bss) from floppy
+	  disk.
+	* .c32 is now one of the extensions searched for automatically.
 
 Changes in 2.07:
 	* MEMDISK: Workaround for BIOSes which go into a snit when
diff --git a/bootsect.inc b/bootsect.inc
index 24ebab6e..f0dc260f 100644
--- a/bootsect.inc
+++ b/bootsect.inc
@@ -27,81 +27,106 @@
 is_bootsector:
 %if IS_SYSLINUX || IS_MDSLINUX
 		; Transfer zero bytes
-		xor cx,cx
+		mov byte [CopySuper],0
 		jmp short load_bootsec
+
 is_bss_sector:
 		; Transfer the superblock
-		mov cx,superblock_len
-load_bootsec:
-		push cx
+		mov byte [CopySuper],superblock_len
 %endif
+load_bootsec:
 		xchg dx,ax
 		shl eax,16
 		xchg dx,ax		; Now EAX = file length
 		mov edi, 100000h
+		push edi		; Save load address
 		call load_high
 		call crlf
 
-%if IS_SYSLINUX || IS_MDSLINUX
-		pop cx
-%endif
-
 		sub edi,100000h
 		push edi		; Save length
 
 %if IS_SYSLINUX || IS_MDSLINUX
+		movzx ecx,byte [CopySuper]
 		jcxz .not_bss
 
 		; For a BSS boot sector we have to patch.
 		mov esi,superblock
 		mov edi,100000h+(superblock-bootsec)
-		movzx ecx,cx
 		call bcopy
 
 .not_bss:
 %endif
-;
-; Prepare for shutting down
-;
-		call vgaclearmode
+
 		xor edx,edx
-		xor eax,eax
+		xor esi,esi
 %if IS_SYSLINUX || IS_MDSLINUX
-		mov dl,[bsDriveNumber]
+		; Restore original FDC table
+		mov eax,[OrigFDCTabPtr]
+		mov [fdctab],eax
 
-		mov si,PartInfo
+		mov dl,[bsDriveNumber]
+		mov si,PartInfo		; Partition info buffer
 		mov di,800h-18		; Put partition info here
 		push di
 		mov cx,8		; 16 bytes
+		xor ax,ax
 		rep movsw
 		pop si			; DS:SI points to partition info
 %elif IS_ISOLINUX
 		mov dl,[DriveNo]
 %elif IS_PXELINUX
-		; Close the UDP stack so the PXE stack is in a known state for
-		; the new NBP
+		mov byte [KeepPXE],1	; Chainloading another NBP
 		call reset_pxe
 %endif
+		xor bx,bx
 
-		pop ecx			; Byte count to copy
+; 
+; Entrypoint for "shut down and replace bootstrap" -- also invoked by
+; the COMBOOT API.  This routine expects two dword on the stack:
+; linear address and length.  Additionally, the values of ESI and EDX
+; are passed on to the new bootstrap; the value of BX becomes the new
+; DS.
+; 
+replace_bootstrap:
+
+		;
+		; Prepare for shutting down
+		;
+		call vgaclearmode
+
+		;
+		; Set up initial stack frame (not used by PXE if keeppxe is set)
+		;
+		xor ax,ax
+		mov ds,ax
+		mov es,ax		
 
-		cli
-		xor ebx,ebx
-		mov ds,bx
-		mov es,bx
 %if IS_PXELINUX
-		lss sp,[InitStack]	; Reset stack to PXE original
-%else
-		mov esp,7C00h
-		pushfd
-		pushad
-		push bx	; ds
-		push bx ; es
-		push bx ; fs
-		push bx	; gs
+		test byte [KeepPXE],01h
+		jz .stdstack
+		les di,[InitStack]	; Reset stack to PXE original
+		jmp .stackok
 %endif
+.stdstack:
+		mov di,7C00h-44
+		push di
+		mov cx,22		; 44 bytes
+		rep stosw
+		pop di
+.stackok:
+
+		mov [es:di+28],edx
+		mov [es:di+12],esi
+		mov [es:di+6],bx
 
-		mov esi,100000h		; Copy from...
+		pop ecx			; Byte count to copy
+		pop esi			; Copy from...
+
+		cli
+		mov ax,es
+		mov ss,ax
+		movzx esp,di
 		mov edi,7C00h		; Copy to...
 
 		jmp bcopy_over_self
diff --git a/comboot.doc b/comboot.doc
index 5d1a9547..768bf3c3 100644
--- a/comboot.doc
+++ b/comboot.doc
@@ -439,7 +439,7 @@ AX=000Ch	Perform final cleanup
 	MAKE SURE TO DISABLE INTERRUPTS, AND INSTALL NEW GDT AND IDTS
 	BEFORE OVERWRITING THESE MEMORY AREAS.
 
-	The permissible values for DX are as follows:
+	The permissible values for DX is an OR of these values:
 
 	SYSLINUX:	0000h	Normal cleanup
 
@@ -450,3 +450,28 @@ AX=000Ch	Perform final cleanup
 
 	All other values are undefined, and may have different
 	meanings in future versions of SYSLINUX.
+
+
+AX=000Dh	Cleanup and replace bootstrap code
+	Input:	AX	000Ch
+		DX	derivative-specific flags (see previous function)
+		EDI	bootstrap code (linear address, can be in high memory)
+		ECX	bootstrap code length in bytes (max 
+		EBX(!)	initial value of EDX after bootstrap
+		ESI	initial value of ESI after bootstrap
+		DS	initial value of DS after bootstrap
+	Output:	None
+
+	This routine performs final cleanup, then takes a piece of
+	code, copies it over the primary bootstrap at address 7C00h,
+	and jumps to it.  This can be used to chainload boot sectors,
+	MBRs, bootstraps, etc.
+
+	Normal boot sectors expect DL to contain the drive number,
+	and, for hard drives (DL >= 80h) DS:SI to contain a pointer to
+	the 16-byte partition table entry.  The memory between
+	600h-7FFh is available to put the partition table entry in.
+
+	For PXELINUX, if the PXE stack is not unloaded, all registers
+	(except DS, ESI and EDX) and the stack will be set up as they
+	were set up by the PXE ROM.
diff --git a/comboot.inc b/comboot.inc
index c8dbff11..e421d67f 100644
--- a/comboot.inc
+++ b/comboot.inc
@@ -518,7 +518,9 @@ comapi_cleanup:
 		; Unload PXE if requested
 		test dl,3
 		setnz [KeepPXE]
+		sub bp,sp		; unload_pxe may move the stack around
 		call unload_pxe
+		add bp,sp		; restore frame pointer...
 %elif IS_SYSLINUX || IS_MDSLINUX
 		; Restore original FDC table
 		mov eax,[OrigFDCTabPtr]
@@ -531,6 +533,19 @@ comapi_cleanup:
 		clc
 		ret
 
+
+;
+; INT 22h AX=000Dh	Clean up then replace bootstrap
+;
+comapi_chainboot:
+		call comapi_cleanup
+		mov esi,P_ESI
+		mov edx,P_EBX
+		mov bx,P_DS
+		push P_EDI
+		push P_ECX
+		jmp replace_bootstrap
+
 ;
 ; This stuff should really be in the data section...
 ;
@@ -567,6 +582,7 @@ int22_table:
 		dw comapi_derinfo		; 000A derivative-specific info
 		dw comapi_serialcfg		; 000B get serial port config
 		dw comapi_cleanup		; 000C perform final cleanup
+		dw comapi_chainboot		; 000D clean up then bootstrap
 int22_count	equ ($-int22_table)/2
 
 APIKeyWait	db 0
diff --git a/isolinux.asm b/isolinux.asm
index ad1c3240..57488cb7 100644
--- a/isolinux.asm
+++ b/isolinux.asm
@@ -224,6 +224,9 @@ Files		resb MAX_OPEN*open_file_t_size
 ;; loading the rest.
 ;;
 bootsec		equ $
+
+StackBuf	equ $-44
+
 _start:		; Far jump makes sure we canonicalize the address
 		cli
 		jmp 0:_start1
@@ -241,7 +244,7 @@ _start1:	mov [cs:InitStack],sp		; Save initial stack pointer
 		mov [cs:InitStack+2],ss
 		xor ax,ax
 		mov ss,ax
-		mov sp,_start			; Set up stack
+		mov sp,StackBuf			; Set up stack
 		mov ds,ax
 		mov es,ax
 		mov fs,ax
@@ -1578,6 +1581,7 @@ exten_table:	db '.cbt'		; COMBOOT (specific)
 		db '.img'		; Disk image
 		db '.bin'		; CD boot sector
 		db '.com'		; COMBOOT (same as DOS)
+		db '.c32'		; COM32
 exten_table_end:
 		dd 0, 0			; Need 8 null bytes here
 
diff --git a/ldlinux.asm b/ldlinux.asm
index 9bbaab9f..13b9b36d 100644
--- a/ldlinux.asm
+++ b/ldlinux.asm
@@ -201,6 +201,7 @@ LoadFlags	resb 1			; Loadflags from kernel
 A20Tries	resb 1			; Times until giving up on A20
 FuncFlag	resb 1			; Escape sequences received from keyboard
 DisplayMask	resb 1			; Display modes mask
+CopySuper	resb 1			; Distinguish .bs versus .bss
 MNameBuf        resb 11            	; Generic mangled file name buffer
 InitRD          resb 11                 ; initrd= mangled name
 KernelCName     resb 13                 ; Unmangled kernel name
@@ -217,7 +218,7 @@ VGAFileMBuf	resb 11			; Mangled VGA image name
 ; "close" to the initial stack pointer offset, in order to
 ; reduce the code size...
 ;
-StackBuf	equ $-32		; Start the stack here (grow down - 4K)
+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-4		; The high dword on the stack
@@ -1421,6 +1422,7 @@ exten_table:	db 'CBT',0		; COMBOOT (specific)
 		db 'BSS',0		; Boot Sector (add superblock)
 		db 'BS ',0		; Boot Sector 
 		db 'COM',0		; COMBOOT (same as DOS)
+		db 'C32',0		; COM32
 exten_table_end:
 		dd 0, 0			; Need 8 null bytes here
 
diff --git a/pxelinux.asm b/pxelinux.asm
index 7b168119..d53924bb 100644
--- a/pxelinux.asm
+++ b/pxelinux.asm
@@ -310,7 +310,7 @@ packet_buf_size	equ $-packet_buf
 
 		section .text
                 org 7C00h
-StackBuf	equ $			; Base of stack if we use our own
+StackBuf	equ $-44		; Base of stack if we use our own
 
 ;
 ; Primary entry point.
@@ -2432,6 +2432,7 @@ bootif_str_len	equ $-bootif_str
 exten_table:	db '.cbt'		; COMBOOT (specific)
 		db '.0', 0, 0		; PXE bootstrap program
 		db '.com'		; COMBOOT (same as DOS)
+		db '.c32'		; COM32
 exten_table_end:
 		dd 0, 0			; Need 8 null bytes here
 
diff --git a/sample/Makefile b/sample/Makefile
index 0bd4512f..900acbd6 100644
--- a/sample/Makefile
+++ b/sample/Makefile
@@ -31,7 +31,7 @@ LIBOBJS	   = conio.o
 
 .SUFFIXES: .lss .c .o .elf .c32
 
-all: syslogo.lss comecho.com hello.c32 hello2.c32 filetest.c32 c32echo.c32
+all: syslogo.lss comecho.com hello.c32 hello2.c32 filetest.c32 c32echo.c32 fd.c32
 
 %.o: %.S
 	$(CC) $(SFLAGS) -c -o $@ $<
diff --git a/sample/fd.c b/sample/fd.c
new file mode 100644
index 00000000..03e13d1a
--- /dev/null
+++ b/sample/fd.c
@@ -0,0 +1,63 @@
+#ident "$Id$"
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2003 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.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * fd.c
+ *
+ * Chainload a floppy disk (currently rather braindead.)
+ */
+
+#include <com32.h>
+#define NULL ((void *)0)
+
+int printf(const char *, ...);
+unsigned int atou(const char *);
+
+int __start(void)
+{
+  int whichfd = atou(__com32.cs_cmdline);
+  static com32sys_t inreg, outreg; /* In bss, so zeroed automatically */
+  int retry;
+
+  for ( retry = 0 ; retry < 6 ; retry++ ) {
+    printf(">");
+    inreg.eax.w[0] = 0x0201;	/* Read one sector */
+    inreg.ecx.w[0] = 0x0001;	/* Cyl 0 sector 1 */
+    inreg.edx.b[1] = 0;		/* Head 0 */
+    inreg.edx.b[0] = whichfd;	/* Drive number */
+    inreg.es = SEG(__com32.cs_bounce); /* Read into the bounce buffer */
+    inreg.ebx.w[0] = OFFS(__com32.cs_bounce);
+    __com32.cs_intcall(0x13, &inreg, &outreg);
+
+    if ( (outreg.eflags.l & 1) == 0 )
+      break;
+  }
+
+  if ( (outreg.eflags.l & 1) == 0 ) {
+    printf("!\n");
+    inreg.eax.w[0] = 0x000d;
+    inreg.edx.w[0] = 0;
+    inreg.edi.l    = (uint32_t) __com32.cs_bounce;
+    inreg.ecx.l    = 512;
+    inreg.ebx.l    = whichfd & 0xff;
+    inreg.esi.l    = 0;		/* No partitions */
+    inreg.ds       = 0;		/* No partitions */
+    __com32.cs_intcall(0x22, &inreg, NULL);
+  }
+
+  /* If we get here, badness happened */
+  return 255;
+}
+
+
+