diff options
| -rw-r--r-- | sys/arch/i386/boot/start.S | 123 |
1 files changed, 36 insertions, 87 deletions
diff --git a/sys/arch/i386/boot/start.S b/sys/arch/i386/boot/start.S index 187c60129fe..288c75326ad 100644 --- a/sys/arch/i386/boot/start.S +++ b/sys/arch/i386/boot/start.S @@ -1,9 +1,6 @@ -/* $OpenBSD: start.S,v 1.4 1996/06/02 11:18:14 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 @@ -58,7 +55,7 @@ WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. #define addr32 .byte 0x67 #define data32 .byte 0x66 -BOOTSEG = 0x1000 # boot will be loaded here (below 640K) +BOOTSEG = 0x0100 # boot will be loaded here (below 640K) BOOTSTACK = 0xfffc # boot stack SIGNATURE = 0xaa55 LOADSZ = 15 # size of unix boot @@ -106,22 +103,21 @@ start1: popl %edx #endif -#ifdef FDDEBUG +#ifdef DEBUG data32 movl $one, %esi data32 call message #endif -#if !defined(NOFD) && !defined(NOHD) + # bootstrap passes us drive number in %dl - testb $0x80, %dl + cmpb $0x80, %dl data32 - jnz hd -#endif -#ifndef NOFD + jae hd + fd: # reset the disk system -#ifdef FDDEBUG +#ifdef DEBUG data32 movl $two, %esi data32 @@ -129,7 +125,7 @@ fd: #endif movb $0x00, %ah int $0x13 -#ifdef FDDEBUG +#ifdef DEBUG data32 movl $three, %esi data32 @@ -139,11 +135,10 @@ fd: movl $0x0001, %ecx # cyl 0, sector 1 movb $0x00, %dh # head # XXX Override the drive number. - # movb $0x00, %dl + movb $0x00, %dl data32 jmp load -#endif -#ifndef NOHD + hd: /**** load sector 0 into the BOOTSEG ****/ #ifdef DEBUG data32 @@ -156,20 +151,28 @@ 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 active partition *****/ + /***# find the first 386BSD partition *****/ data32 movl $PARTSTART, %ebx data32 movl $NUMPART, %ecx again: addr32 - cmpb $BOOTABLE, %es:(%ebx) + movb %es:4(%ebx), %al + cmpb $BSDPART, %al data32 je found data32 @@ -180,8 +183,13 @@ again: movl $enoboot, %esi data32 jmp err_stop -#endif +#else /* !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 @@ -194,74 +202,25 @@ 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 -#ifndef NOHD - testb $0x80, %dl /* no fdisk partion table on floppy */ - data32 - jz dobsd - - addr32 - movb %es:4(%ebx), %al - cmpb $BSDPART, %al - je dobsd - - ljmp $0, $0x7c00 + # 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". -dobsd: -#endif #ifdef DEBUG data32 movl $six, %esi @@ -269,10 +228,6 @@ dobsd: 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) @@ -315,6 +270,7 @@ message: data32 pushl %edx +#endif nextb: cld lodsb # load a byte into %al @@ -345,10 +301,7 @@ done: popl %eax data32 ret -#else /* !DOSREAD */ - movb $0xff, %dl - jmp _C_LABEL(boot2) -#endif /* DOSREAD */ + /* Conventional GDT indexes. */ BOOT_CS_INDEX = 3 @@ -370,7 +323,7 @@ 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 @@ -410,18 +363,15 @@ stop: /* error messages */ -#if defined(DEBUG) && !defined(DOSREAD) -#ifdef FDDEBUG +#ifdef DEBUG 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 */ -#ifndef DOSREAD +#endif DEBUG eread: .asciz "Read error\r\n" enoboot: .asciz "No bootable partition\r\n" endofcode: @@ -440,7 +390,6 @@ endofcode: . = _C_LABEL(boot1) + 0x1fe .short SIGNATURE . = _C_LABEL(boot1) + 0x200 -#endif .globl _disklabel _disklabel: . = _C_LABEL(boot1) + 0x400 |