Next x86 biosboot/boot diff

From: Tobias Weingartner <weingart(at)natasha.tepid.org>
Date: Tue Jan 28 2003 - 05:07:14 EST

This is the next step in the move to an LBA enabled /boot system. These diffs are to move the real->prot switch into /boot (from biosboot), saving us some very much needed bytes within biosboot. Note, the biosboot and /boot image always go together in lockstep. IE: an old /boot and a newer biosboot will not play nice (especially after you apply these patches). The same is true for an old biosboot, and new /boot.

I need people to test this. So far I've tested on 4 different machines, and they all work. However, daemons lurk in these waters... the more people that can apply this diff, build, install, and then copy a new /boot, and installboot this, the better.

Basic steps:

Apply diff.
cd /sys/arch/i386/stand
make obj && make && make install
cp /usr/mdec/boot /boot
/usr/mdec/installboot -v /boot /usr/mdec/biosboot wd0

Adjust as necessary to your configuration.

Please send results, comments, flames, whatever my way.

--Toby.
PS: Diff also available at
http://www.tepid.org/~weingart/OpenBSD/i386-next.diff PPS: You may wish to have a boot floppy handy, just in case.

Index: biosboot/biosboot.S

---

RCS file: /cvs/src/sys/arch/i386/stand/biosboot/biosboot.S,v retrieving revision 1.32
diff -u -r1.32 biosboot.S

--- biosboot/biosboot.S	28 Aug 2002 20:15:34 -0000	1.32
+++ biosboot/biosboot.S	28 Jan 2003 09:50:40 -0000

@@ -39,7 +39,7 @@
#define addr32 .byte 0x67
#define data32 .byte 0x66
 

-#define	BLKCNT	12
+#define	BLKCNT	55
 


 #define BOOTSEG		0x07c0	/* boot loaded here */


 #define BOOTSTACK	0xfffc	/* stack starts here */


@@ -212,52 +212,16 @@
 	putc('P')

#endif
 

• /* change to protected mode */
• /* guarantee that interrupts are disabled when in prot mode */
• cli -
• /* load the gdtr */
• addr32 + /* Push disk #, and magic */ + movzbl %dl, %eax /* drive number is in the lowest byte */ data32
• lgdt Gdtr -
• /* set the PE bit of CR0 */
• movl %cr0, %eax + pushl %eax data32
• orl $CR0_PE, %eax
• movl %eax, %cr0 + pushl $BOOTMAGIC /* use some magic */
• /*
• * make intrasegment jump to flush the processor pipeline and
• * reload CS register
• */ + /* jmp to /boot */ data32
• ljmp $8, $(BOOTSEG << 4) + 1f - -1: /*
• * 32bit mode
• * set up %ds, %ss, %es, etc
• */
• movl $0x10, %eax
• movl %ax, %ds
• movl %ax, %ss
• movl %ax, %es
• movl %ax, %fs
• movl %ax, %gs
• movl $BOOTSTACK, %esp - -#ifdef BDEBUG
• movl $0xb8004, %ebx
• movl $0x074f0747, (%ebx) -#endif -
• movzbl %dl, %eax /* drive number is in the lowest byte */
• pushl %eax
• pushl $BOOTMAGIC /* use some magic */ -
• /* jmp /boot */
• ljmp $8, $(LOADADDR + 0x20)
• /* not reached */ + ljmp $(LOADADDR >> 4), $0x20

 /*

• Display string @@ -305,26 +269,6 @@ data32 popl %eax ret - - .align 3 -1: /* 0x00 : null */ - .long 0, 0 - /* 0x08 : flat code */ - .word 0xFFFF # lolimit - .word 0 # lobase - .byte 0 # midbase - .byte SDT_MEMERAC | 0 | 0x80 # RWXAC, dpl = 0, present - .byte 0xf | 0 | 0x40 | 0x80 # hilimit, xx, 32bit, 4k granularity - .byte 0 # hibase - /* 0x10 : flat data */ - .word 0xFFFF # lolimit - .word 0 # lobase - .byte 0 # midbase - .byte SDT_MEMRWA | 0 | 0x80 # RWA, dpl = 0, present - .byte 0xf | 0 | 0x40 | 0x80 # hilimit, xx, 32bit, 4k granularity - .byte 0 # hibase -Gdtr: .word . - 1b - .long (BOOTSEG << 4) + 1b

         .globl _block_table, _block_count
 _block_count:
Index: boot/Makefile

---

RCS file: /cvs/src/sys/arch/i386/stand/boot/Makefile,v retrieving revision 1.29
diff -u -r1.29 Makefile

--- boot/Makefile	19 Oct 2000 17:14:01 -0000	1.29
+++ boot/Makefile	28 Jan 2003 09:50:40 -0000

@@ -40,6 +40,7 @@
 .include <bsd.prog.mk>  

 CPPFLAGS+=-DBOOTMAGIC=$(BOOTMAGIC) ${DEBUGFLAGS} +CPPFLAGS+=-DLINKADDR=${LINKADDR}
 CFLAGS+=$(SACFLAGS)
#AFLAGS+=-Wa,-R
# AFLAGS+=-Wa,-a

Index: boot/srt0.S

---

RCS file: /cvs/src/sys/arch/i386/stand/boot/srt0.S,v retrieving revision 1.10
diff -u -r1.10 srt0.S

--- boot/srt0.S	14 May 1998 20:59:12 -0000	1.10
+++ boot/srt0.S	28 Jan 2003 09:50:40 -0000

@@ -32,33 +32,92 @@
  *
  */
#include <machine/asm.h>

+#include 
+
+#define addr32	.byte 0x67
+#define data32	.byte 0x66
+#define BOOTSTACK	0xfffc	/* stack starts here */
 
 	.globl	_C_LABEL(end)
 	.globl	_C_LABEL(edata)
 	.globl	_C_LABEL(boot)
 	.globl	_C_LABEL(_rtt)
 	.globl	_ASM_LABEL(pmm_init)
+	.globl	Gdtr
 
 	.text
 	.globl	start
 start:
+	data32
+	popl	%eax
+	data32
+	cmpl	$BOOTMAGIC, %eax
+	je	1f
+#ifdef DEBUG
+	movl	$0xb80a8, %ebx
+	movl	$0xcf41cf4d, (%ebx)

+#endif
+1:
#ifdef DEBUG

 	movl	$0xb80a0, %ebx
 	movl	$0x07420742, (%ebx)


 #endif


+	/* Save disk while we switch */
+	data32
+	popl	%edx
+
+	/* guarantee that interrupts are disabled when in prot mode */
+	cli
+
+	/* Setup ds == cs, such that lgdt will work */
+	pushl %cs
+	popl %ds
+
+	/* change to protected mode */
+	/* load the gdtr */
+	addr32
+	data32
+	lgdt	(Gdtr - LINKADDR)
+
+	/* set the PE bit of CR0 */
+	movl	%cr0, %eax
+	data32
+	orl	$CR0_PE, %eax
+	movl	%eax, %cr0 
+
+	/*
+	 * make intrasegment jump to flush the processor pipeline and
+	 * reload CS register
+	 */
+	data32
+	ljmp	$8, $1f
+
+1:	/*
+	 * 32bit mode
+	 * set up %ds, %ss, %es, etc
+	 */
+	movl	$0x10, %eax
+	movl	%ax, %ds
+	movl	%ax, %ss
+	movl	%ax, %es
+	movl	%ax, %fs
+	movl	%ax, %gs
+	movl	$BOOTSTACK, %esp
+
+#ifdef	BDEBUG
+	movl	$0xb8004, %ebx
+	movl	$0x074f0747, (%ebx)
+#endif
+
+	/* Restore disk # on stack */
+	pushl	%edx
+
+	/* Now do the real thing */
 	call	_ASM_LABEL(pmm_init)
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 #ifdef DEBUG


 	movl	$0xb80a4, %ebx
 	movl	$0x07520752, (%ebx)


 #endif


-	popl	%eax
-	cmpl	$BOOTMAGIC, %eax
-	je	1f
-#ifdef DEBUG
-	movl	$0xb80a8, %ebx
-	movl	$0xcf41cf4d, (%ebx)

-#endif
-1:

 	/* zero .bss */
 	xorl	%eax, %eax
 	movl	$_C_LABEL(end), %ecx

Index: libsa/gidt.S

---

RCS file: /cvs/src/sys/arch/i386/stand/libsa/gidt.S,v retrieving revision 1.24
diff -u -r1.24 gidt.S

--- libsa/gidt.S	17 Sep 2001 13:10:09 -0000	1.24
+++ libsa/gidt.S	28 Jan 2003 09:50:40 -0000
@@ -276,7 +276,8 @@
 	.byte	0xf | 0 | 0 | 0		# hilimit, xx, 16bit, byte granularity
 	.byte	(LINKADDR >> 20) & 0xff	# hibase
 
-Gdtr:	.word	. - gdt - 1
+	.globl	Gdtr
+Gdtr:	.word	. - gdt
 	.long	gdt
 	.word	0

Received on Tue Jan 28 05:08:28 2003