do boot from active partition.

this tested w/ DOS(win95), and BSD.

1 files changed, 80 insertions, 30 deletions

diff --git a/sys/arch/i386/boot/start.S b/sys/arch/i386/boot/start.S
index 288c75326ad..5efeafc340e 100644
--- a/sys/arch/i386/boot/start.S
+++ b/sys/arch/i386/boot/start.S
@@ -1,6 +1,9 @@
+/*	$OpenBSD: start.S,v 1.3 1996/05/18 10:33:14 mickey Exp $	*/
 /*	$NetBSD: start.S,v 1.12 1995/01/18 17:34:18 mycroft Exp $	*/
 
-/*
+/*-
+ *
+ * Changes by Michael Shalayeff May 1996
  * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
  *
  * Mach Operating System
@@ -55,7 +58,7 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #define	addr32	.byte 0x67
 #define	data32	.byte 0x66
 
-BOOTSEG		=	0x0100	# boot will be loaded here (below 640K)
+BOOTSEG		=	0x1000	# boot will be loaded here (below 640K)
 BOOTSTACK	=	0xfffc	# boot stack
 SIGNATURE	=	0xaa55
 LOADSZ		=	15	# size of unix boot
@@ -103,21 +106,22 @@ start1:
 	popl	%edx
 #endif
 
-#ifdef	DEBUG
+#ifdef	FDDEBUG
 	data32
 	movl	$one, %esi
 	data32
 	call	message
 #endif
-
+#if	!defined(NOFD) && !defined(NOHD)
 	# bootstrap passes us drive number in %dl
 	cmpb	$0x80, %dl
 	data32
 	jae	hd
-
+#endif
+#ifndef	NOFD
 fd:
 #	reset the disk system
-#ifdef	DEBUG
+#ifdef	FDDEBUG
 	data32
 	movl	$two, %esi
 	data32
@@ -125,7 +129,7 @@ fd:
 #endif
 	movb	$0x00, %ah
 	int	$0x13
-#ifdef	DEBUG
+#ifdef	FDDEBUG
 	data32
 	movl	$three, %esi
 	data32
@@ -138,7 +142,8 @@ fd:
 	movb	$0x00, %dl
 	data32
 	jmp	load
-
+#endif
+#ifndef	NOHD
 hd:	/**** load sector 0 into the BOOTSEG ****/
 #ifdef	DEBUG
 	data32
@@ -151,28 +156,20 @@ hd:	/**** load sector 0 into the BOOTSEG ****/
 	xorl	%ebx, %ebx	# %bx = 0
 	data32
 	movl	$0x0001, %ecx
-#ifdef	DEBUG
-	data32
-	movl	$five, %esi
-	data32
-	call	message
-#endif
 	data32
 	andl	$0xff, %edx
-	/*mov	$0x0080, %edx*/
 	int	$0x13
 	data32
 	jb	read_error
 
-	/***# find the first 386BSD partition *****/
+	/***# find the first active partition *****/
 	data32
 	movl	$PARTSTART, %ebx
 	data32
 	movl	$NUMPART, %ecx
 again:
 	addr32
-	movb    %es:4(%ebx), %al
-	cmpb	$BSDPART, %al
+	cmpb    $BOOTABLE, %es:(%ebx)
 	data32
 	je	found
 	data32
@@ -183,13 +180,13 @@ again:
 	movl	$enoboot, %esi
 	data32
 	jmp	err_stop
+#endif
 #else /* !DOSREAD */
-      movb    $0xff, %dl
-      jmp     _C_LABEL(boot2)
-#endif /* DOSREAD */
+	movb	$0xff, %dl
+	jmp	_C_LABEL(boot2)
 
+#endif	/* DOSREAD */
 
-#ifndef DOSREAD
 /*
 # BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory
 #       Call with       %ah = 0x2
@@ -202,25 +199,74 @@ again:
 #       Return:
 #                       %al = 0x0 on success; err code on failure
 */
-
+#ifndef	NOHD
 found:
 	addr32
 	movb	%es:1(%ebx), %dh /* head */
 	addr32
 	movl	%es:2(%ebx), %ecx /*sect, cyl (+ 2 bytes junk in top word) */
+	data32
+	pushl	%ecx
+
+	addr32
+	movb	%es:4(%ebx), %al
+	cmpb	$BSDPART, %al
+	je	loadbsd
+
+	# set up %ds
+	movl	%cs, %ax
+	movl	%ax, %ds
+
+	# relocate the code to leave the space for next stage
+	movl	$0x5c0, %ax
+	movl	%ax, %es
+	data32
+	xorl	%esi, %esi
+	data32
+	xorl	%edi, %edi
+	data32
+	movl	$0x100, %ecx
+	cld
+	rep
+	movsl
+	# jump to the new code
+	data32
+	ljmp $0x5c0, $start2
+
+start2:
+	movl	$0x7c0, %ax
+	movl	%ax, %es
 
+loadbsd:
+	data32
+	popl	%ecx
+#endif
 load:
+	data32
+	pushl	%ebx
 	movb	$0x2, %ah	/* function 2 */
 	movb	$LOADSZ, %al	/* number of blocks */
 	xorl	%ebx, %ebx	/* %bx = 0, put it at 0 in the BOOTSEG */
 	int	$0x13
 	data32
+	popl	%ebx
+	data32
 	jb	read_error
 
-	# ljmp to the second stage boot loader (boot2).
-	# After ljmp, %cs is BOOTSEG and boot1 (512 bytes) will be used
-	# as an internal buffer "intbuf".
+#ifndef	NOHD
+	cmpb	$0x80, %dl	/* no concurent dos on floppy */
+	data32
+	jl	dobsd
+
+	addr32
+	movb	%es:4(%ebx), %al
+	cmpb	$BSDPART, %al
+	je	dobsd
+
+	ljmp	$0, $0x7c00
 
+dobsd:
+#endif
 #ifdef	DEBUG
 	data32
 	movl	$six, %esi
@@ -228,6 +274,10 @@ load:
 	call	message
 #endif
 
+	# ljmp to the second stage boot loader (boot2).
+	# After ljmp, %cs is BOOTSEG and boot1 (512 bytes) will be used
+	# as an internal buffer "intbuf".
+
 	data32
 	ljmp	$BOOTSEG, $_C_LABEL(boot2)
 
@@ -270,7 +320,6 @@ message:
 	data32
 	pushl	%edx
 
-#endif
 nextb:
 	cld
 	lodsb			# load a byte into %al
@@ -302,7 +351,6 @@ done:
 	data32
 	ret
 
-
 /* Conventional GDT indexes. */
 BOOT_CS_INDEX	=	3
 BOOT_CS16_INDEX	=	5
@@ -323,7 +371,7 @@ ENTRY(boot2)
 	/* fix up GDT entries for bootstrap */
 #define FIXUP(gdt_index) \
 	addr32; \
-	movl	%eax, _C_LABEL(Gdt)+(8*gdt_index)+2;	/* actually movw %ax */ \
+	movl	%eax, _C_LABEL(Gdt)+(8*gdt_index)+2;  /* actually movw %ax */ \
 	addr32; \
 	movb	%bl, _C_LABEL(Gdt)+(8*gdt_index)+4
 
@@ -364,14 +412,16 @@ stop:
 /* error messages */
 
 #ifdef	DEBUG
+#ifdef	FDDEBUG
 one:	.asciz		"1\r\n"
 two:	.asciz		"2\r\n"
 three:	.asciz		"3\r\n"
+#endif	/* FDDEBUG */
 four:	.asciz		"4\r\n"
 five:	.asciz		"5\r\n"
 six:	.asciz		"6\r\n"
 seven:	.asciz		"7\r\n"
-#endif	DEBUG
+#endif	/* DEBUG */
 eread:	.asciz		"Read error\r\n"
 enoboot: .asciz		"No bootable partition\r\n"
 endofcode: