diff options
| -rw-r--r-- | sys/boot/i386/mbr/Makefile | 28 | ||||
| -rw-r--r-- | sys/boot/i386/mbr/mbr.m4 | 51 | ||||
| -rw-r--r-- | sys/boot/i386/mbr/mbr.s | 98 |
3 files changed, 177 insertions, 0 deletions
diff --git a/sys/boot/i386/mbr/Makefile b/sys/boot/i386/mbr/Makefile new file mode 100644 index 0000000..ef206e5 --- /dev/null +++ b/sys/boot/i386/mbr/Makefile @@ -0,0 +1,28 @@ +# $Id: $ + +PROG= mbr +NOMAN= +STRIP= +BINDIR?= /boot +BINMODE= 444 + +M4?= m4 + +ORG= 0x600 + +mbr: mbr.o +.if ${OBJFORMAT} == aout + ${LD} -N -s -T ${ORG} -o mbr.out mbr.o + dd if=mbr.out of=${.TARGET} ibs=32 skip=1 +.else + ${LD} -N -e start -Ttext ${ORG} -o mbr.out mbr.o + objcopy -S -O binary mbr.out ${.TARGET} +.endif + +mbr.o: mbr.m4 mbr.s + (cd ${.CURDIR}; ${M4} mbr.m4 mbr.s) | \ + ${AS} ${AFLAGS} -o ${.TARGET} + +CLEANFILES+= mbr.out mbr.o + +.include <bsd.prog.mk> diff --git a/sys/boot/i386/mbr/mbr.m4 b/sys/boot/i386/mbr/mbr.m4 new file mode 100644 index 0000000..768e262 --- /dev/null +++ b/sys/boot/i386/mbr/mbr.m4 @@ -0,0 +1,51 @@ +# +# Copyright (c) 1999 Robert Nordier +# All rights reserved. +# +# Redistribution and use in source and binary forms are freely +# permitted provided that the above copyright notice and this +# paragraph and the following disclaimer are duplicated in all +# such forms. +# +# This software is provided "AS IS" and without any express or +# implied warranties, including, without limitation, the implied +# warranties of merchantability and fitness for a particular +# purpose. +# + +# $Id: $ + +define(_al,0x0)dnl +define(_cl,0x1)dnl +define(_dl,0x2)dnl +define(_bl,0x3)dnl +define(_ah,0x4)dnl +define(_ch,0x5)dnl +define(_dh,0x6)dnl +define(_bh,0x7)dnl + +define(_ax,0x0)dnl +define(_cx,0x1)dnl +define(_dx,0x2)dnl +define(_bx,0x3)dnl +define(_sp,0x4)dnl +define(_bp,0x5)dnl +define(_si,0x6)dnl +define(_di,0x7)dnl + +define(_bx_si,0x0)dnl +define(_bx_di,0x1)dnl +define(_bp_si,0x2)dnl +define(_bp_di,0x3)dnl +define(_si_,0x4)dnl +define(_di_,0x5)dnl +define(_bp_,0x6)dnl +define(_bx_,0x7)dnl + +define(cmpbr0,`.byte 0x38; .byte ($1 << 0x3) | $2')dnl +define(cmpwi2,`.byte 0x81; .byte 0xb8 | $3; .word $2; .word $1')dnl +define(movb0r,`.byte 0x8a; .byte ($2 << 0x3) | $1')dnl +define(movb1r,`.byte 0x8a; .byte 0x40 | ($3 << 0x3) | $2; .byte $1')dnl +define(movw1r,`.byte 0x8b; .byte 0x40 | ($3 << 0x3) | $2; .byte $1')dnl +define(movwir,`.byte 0xb8 | $2; .word $1')dnl +define(jmpnwi,`.byte 0xe9; .word $1 - . - 0x2')dnl diff --git a/sys/boot/i386/mbr/mbr.s b/sys/boot/i386/mbr/mbr.s new file mode 100644 index 0000000..9bdb5d5 --- /dev/null +++ b/sys/boot/i386/mbr/mbr.s @@ -0,0 +1,98 @@ +# +# Copyright (c) 1999 Robert Nordier +# All rights reserved. +# +# Redistribution and use in source and binary forms are freely +# permitted provided that the above copyright notice and this +# paragraph and the following disclaimer are duplicated in all +# such forms. +# +# This software is provided "AS IS" and without any express or +# implied warranties, including, without limitation, the implied +# warranties of merchantability and fitness for a particular +# purpose. +# + +# $Id: $ + +# Master boot record + + .set LOAD,0x7c00 # Load address + .set EXEC,0x600 # Execution address + .set PT_OFF,0x1be # Partition table + .set MAGIC,0xaa55 # Magic: bootable + + .set NDRIVE,0x8 # Drives to support + + .globl start # Entry point + +start: cld # String ops inc + xorl %eax,%eax # Zero + movl %eax,%es # Address + movl %eax,%ds # data + cli # Disable interrupts + movl %eax,%ss # Set up + movwir(LOAD,_sp) # stack + sti # Enable interrupts + movwir(main-EXEC+LOAD,_si) # Source + movwir(main,_di) # Destination + movwir(0x200-(main-start),_cx) # Word count + rep # Relocate + movsb # code + jmpnwi(main-LOAD+EXEC) # To relocated code + +main: xorl %esi,%esi # No active found + movwir(partbl,_bx) # Partition table + movb $0x4,%cl # Entries +main.1: cmpbr0(_ch,_bx_) # Null entry? + je main.2 # Yes + jg err_pt # If bit 7 unset + testl %esi,%esi # Active found? + jnz err_pt # Yes + movl %ebx,%esi # Keep place +main.2: addb $0x10,%bl # Till + loop main.1 # done + testl %esi,%esi # Active found? + jnz main.3 # Yes + int $0x18 # BIOS: Diskless boot + +main.3: cmpb $0x80,%dl # Drive valid? + jb main.4 # No + cmpb $0x80+NDRIVE,%dl # Within range? + jb main.5 # Yes +main.4: movb0r(_si_,_dl) # Load drive +main.5: movb1r(0x1,_si_,_dh) # Load head + movw1r(0x2,_si_,_cx) # Load cylinder:sector + movwir(LOAD,_bx) # Transfer buffer + movwir(0x201,_ax) # BIOS: Read from + int $0x13 # disk + jc err_rd # If error + cmpwi2(MAGIC,0x1fe,_bx_) # Bootable? + jne err_os # No + jmp *%ebx # Invoke bootstrap + +err_pt: movwir(msg_pt,_si) # "Invalid partition + jmp putstr # table" + +err_rd: movwir(msg_rd,_si) # "Error loading + jmp putstr # operating system" + +err_os: movwir(msg_os,_si) # "Missing operating + jmp putstr # system" + +putstr.0: movwir(0x7,_bx) # Page:attribute + movb $0xe,%ah # BIOS: Display + int $0x10 # character +putstr: lodsb # Get character + testb %al,%al # End of string? + jnz putstr.0 # No +putstr.1: jmp putstr.1 # Await reset + +msg_pt: .asciz "Invalid partition table" +msg_rd: .asciz "Error loading operating system" +msg_os: .asciz "Missing operating system" + + .org PT_OFF + +partbl: .fill 0x10,0x4,0x0 # Partition table + .word MAGIC # Magic number |
