diff options
Diffstat (limited to 'sys/pc98/boot/biosboot/boot2.S')
| -rw-r--r-- | sys/pc98/boot/biosboot/boot2.S | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/sys/pc98/boot/biosboot/boot2.S b/sys/pc98/boot/biosboot/boot2.S new file mode 100644 index 0000000..d994d41 --- /dev/null +++ b/sys/pc98/boot/biosboot/boot2.S @@ -0,0 +1,175 @@ +/* + * Mach Operating System + * Copyright (c) 1992, 1991 Carnegie Mellon University + * All Rights Reserved. + * + * Permission to use, copy, modify and distribute this software and its + * documentation is hereby granted, provided that both the copyright + * notice and this permission notice appear in all copies of the + * software, derivative works or modified versions, and any portions + * thereof, and that both notices appear in supporting documentation. + * + * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" + * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR + * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. + * + * Carnegie Mellon requests users of this software to return to + * + * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU + * School of Computer Science + * Carnegie Mellon University + * Pittsburgh PA 15213-3890 + * + * any improvements or extensions that they make and grant Carnegie Mellon + * the rights to redistribute these changes. + * + * from: Mach, Revision 2.2 92/04/04 11:35:26 rpd + * boot2.S,v 1.6 1995/01/25 21:37:40 bde Exp + */ +/* + * Ported to PC-9801 by Yoshio Kimura + */ + +#include "asm.h" + +/* Conventional GDT indexes. */ +#define BOOT_CS_INDEX 3 +#define BOOT_CS16_INDEX 5 +#define BOOT_DS_INDEX 4 + +#ifdef BDE_DEBUGGER +#define DB_CS_INDEX 14 +#define DB_CS16_INDEX 15 +#define DB_DS_INDEX 16 +#define GDT_INDEX 17 +#endif + +/* Vector numbers. */ +#define BREAKPOINT_VECTOR 3 +#define DEBUG_VECTOR 1 + +/* + * boot2() -- second stage boot + */ + +ENTRY(boot2) + data32 + subl %eax, %eax + mov %cs, %ax + mov %ax, %ds + mov %ax, %es + data32 + shll $4, %eax + + /* fix up GDT entries for bootstrap */ +#define FIXUP(gdt_index) \ + addr32; \ + movl %eax, EXT(Gdt)+(8*gdt_index)+2; /* actually movw %ax */ \ + addr32; \ + movb %bl, EXT(Gdt)+(8*gdt_index)+4 + + data32 + shld $16, %eax, %ebx + FIXUP(BOOT_CS_INDEX) + FIXUP(BOOT_CS16_INDEX) + FIXUP(BOOT_DS_INDEX) + + /* fix up GDT pointer */ + data32 + movl %eax, %ecx + data32 + addl $ EXT(Gdt), %eax + addr32 + data32 + movl %eax, EXT(Gdtr)+2 + +#ifdef BDE_DEBUGGER + /* fix up GDT entry for GDT */ + data32 + shld $16, %eax, %ebx + FIXUP(GDT_INDEX) + + /* fix up IDT pointer */ + data32 + addl $ EXT(Idt), %ecx + addr32 + data32 + movl %ecx, EXT(Idtr_prot)+2 + + /* %es = vector table segment for a while */ + push %es + data32 + subl %eax, %eax + mov %ax, %es + + /* fix up GDT entries for bdb */ + data32 + movl $4*DEBUG_VECTOR, %esi + addr32 + movl %es: 2(%esi), %eax /* actually movw to %ax */ + data32 + shll $4, %eax + data32 + shld $16, %eax, %ebx + FIXUP(DB_CS_INDEX) + FIXUP(DB_CS16_INDEX) + FIXUP(DB_DS_INDEX) + + /* Fetch entry points of bdb's protected mode trap handlers. These + * are stored at 2 before the corresponding entry points for real mode. + */ + data32 + subl %ebx, %ebx + addr32 + movl %es: (%esi), %ebx /* actually movw to %bx */ + data32 + subl %ecx, %ecx + addr32 + movl %es: 4*(BREAKPOINT_VECTOR-DEBUG_VECTOR)(%esi), %ecx + /* actually movw to %cx */ + + /* %es = bdb segment for a while */ + data32 + shrl $4, %eax + mov %ax, %es + + /* fix up IDT entries for bdb */ + data32 + subl $2, %ebx /* calculate EA to check it */ + jb 1f /* give up if it would trap */ + addr32 + movl %es: (%ebx), %eax /* actually movw to %ax */ + addr32 + movl %eax, EXT(Idt)+8*DEBUG_VECTOR /* actually movw %ax */ +1: + data32 + subl $2, %ecx + jb 1f + addr32 + movl %es: (%ecx), %eax /* actually movw to %ax */ + addr32 + movl %eax, EXT(Idt)+8*BREAKPOINT_VECTOR /* actually movw %ax */ +1: + + /* finished with groping in real mode segments */ + pop %es +#endif /* BDE_DEBUGGER */ + + /* change to protected mode */ + data32 + call EXT(real_to_prot) + + /* clear the bss */ + movl $ EXT(edata), %edi /* no EXT(_edata) - krufty ld */ + movl $ EXT(end), %ecx /* or EXT(_end) */ + subl %edi, %ecx + subb %al, %al + rep + stosb + + movzbl %dl, %edx /* discard head (%dh) and random high bits */ + pushl %edx + call EXT(boot) +oops: + hlt + jmp oops |
