/* * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992 * * 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. */ /* Copyright 1988, 1989, 1990, 1991, 1992 by Intel Corporation, Santa Clara, California. All Rights Reserved Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appears in all copies and that both the copyright notice and this permission notice appear in supporting documentation, and that the name of Intel not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT, NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include "asm.h" .file "start.s" BOOTSEG = 0x0100 # boot will be loaded here (below 640K) BOOTSTACK = 0xfffc # boot stack SIGNATURE = 0xaa55 LOADSZ = 15 # size of unix boot PARTSTART = 0x1be # starting address of partition table NUMPART = 4 # number of partitions in partition table PARTSZ = 16 # each partition table entry is 16 bytes BSDPART = 0xA5 # value of boot_ind, means bootable partition BOOTABLE = 0x80 # value of boot_ind, means bootable partition .text .globl start ENTRY(boot1) start: # start (aka boot1) is loaded at 0x0:0x7c00 but we want 0x7c0:0 # ljmp to the next instruction to adjust %cs data32 ljmp $0x7c0, $start1 start1: # set up %ds movl %cs, %ax movl %ax, %ds # set up %ss and %esp data32 movl $BOOTSEG, %eax movl %ax, %ss data32 movl $BOOTSTACK, %esp /*** set up %es, (where we will load boot2 to) ***/ movl %ax, %es #ifdef DEBUG data32 movl $one, %esi data32 call message #endif # bootstrap passes us drive number in %dl cmpb $0x80, %dl data32 jae hd fd: # reset the disk system #ifdef DEBUG data32 movl $two, %esi data32 call message #endif movb $0x0, %ah int $0x13 data32 movl $0x0001, %ecx # cyl 0, sector 1 movb $0, %dh # head #ifdef DEBUG data32 movl $three, %esi data32 call message #endif data32 jmp load hd: /**** load sector 0 into the BOOTSEG ****/ #ifdef DEBUG data32 movl $four, %esi data32 call message #endif data32 movl $0x0201, %eax 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 *****/ data32 movl $PARTSTART, %ebx data32 movl $NUMPART, %ecx again: addr32 movb %es:4(%ebx), %al cmpb $BSDPART, %al data32 je found data32 addl $PARTSZ, %ebx data32 loop again data32 movl $enoboot, %esi data32 jmp err_stop /* # BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory # Call with %ah = 0x2 # %al = number of sectors # %ch = cylinder # %cl = sector # %dh = head # %dl = drive (0x80 for hard disk, 0x0 for floppy disk) # %es:%bx = segment:offset of buffer # Return: # %al = 0x0 on success; err code on failure */ found: addr32 movb %es:1(%ebx), %dh /* head */ addr32 movl %es:2(%ebx), %ecx /*sect, cyl (+ 2 bytes junk in top word) */ load: 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 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". #ifdef DEBUG data32 movl $six, %esi data32 call message #endif data32 ljmp $BOOTSEG, $ EXT(boot2) # # read_error # read_error: data32 movl $eread, %esi err_stop: data32 call message data32 jmp stop # # message: write the error message in %ds:%esi to console # message: /* # Use BIOS "int 10H Function 0Eh" to write character in teletype mode # %ah = 0xe %al = character # %bh = page %bl = foreground color (graphics modes) */ data32 pushl %eax data32 pushl %ebx data32 movl $0x0001, %ebx cld nextb: lodsb # load a byte into %al cmpb $0x0, %al data32 je done movb $0xe, %ah int $0x10 # display a byte data32 jmp nextb done: data32 popl %ebx data32 popl %eax data32 ret stop: cli hlt /* error messages */ #ifdef DEBUG one: .asciz "1\r\n" two: .asciz "2\r\n" three: .asciz "3\r\n" four: .asciz "4\r\n" five: .asciz "5\r\n" six: .asciz "6\r\n" seven: .asciz "7\r\n" #endif DEBUG eread: .asciz "Read error\r\n" enoboot: .asciz "No bootable partition\r\n" endofcode: /* throw in a partition in case we are block0 as well */ /* flag, head, sec, cyl, typ, ehead, esect, ecyl, start, len */ . = EXT(boot1) + PARTSTART .byte 0x0,0,0,0,0,0,0,0 .long 0,0 .byte 0x0,0,0,0,0,0,0,0 .long 0,0 .byte 0x0,0,0,0,0,0,0,0 .long 0,0 .byte BOOTABLE,0,1,0,BSDPART,255,255,255 .long 0,50000 /* the last 2 bytes in the sector 0 contain the signature */ . = EXT(boot1) + 0x1fe .value SIGNATURE ENTRY(disklabel) . = EXT(boot1) + 0x400