diff options
Diffstat (limited to 'sys/arch/i386/boot/start.S')
| -rw-r--r-- | sys/arch/i386/boot/start.S | 110 |
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: |