mbr.S revision 1.1.2.2
1 /* $NetBSD: mbr.S,v 1.1.2.2 2006/09/03 15:23:20 yamt Exp $ */ 2 3 /*- 4 * Copyright (c) 2005 NONAKA Kimihiro 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <machine/asm.h> 30 #include <sys/bootblock.h> 31 32 ENTRY(start) 33 mova mbr_end, r0 34 mov r0, r11 /* r11: relocate address */ 35 36 mov.w mbr_size, r2 37 sub r2, r0 38 mov r0, r10 /* r10: loaded address */ 39 40 mov.w stack_offset, r1 41 add r1, r0 42 mov r0, r15 /* r15: stack pointer */ 43 44 /* relocate code */ 45 mova jmp_start, r0 46 mov r0, r13 47 add r2, r13 /* calc jump address */ 48 49 mov r10, r0 50 mov r11, r1 51 1: mov.b @r0+, r3 52 dt r2 53 mov.b r3, @r1 54 bf/s 1b 55 add #1, r1 56 57 jmp @r13 58 nop 59 60 .align 2 61 jmp_start: 62 /* enable cache */ 63 mov #0, r4 64 mov #6, r0 65 trapa #0x3f 66 67 #ifndef NO_BANNER 68 /* print banner */ 69 mova banner, r0 70 bsr message_crlf 71 mov r0, r4 72 #endif 73 74 /* search bootable partition */ 75 mov.w part_offset, r12 76 add r11, r12 /* r12: pointer to partition entry */ 77 mov #MBR_PART_COUNT, r8 /* r8: partition loop counter */ 78 loop_part: 79 mov.b @(4, r12), r0 80 cmp/eq #MBR_PTYPE_UNUSED, r0 81 bt next_part 82 83 /* check active partition */ 84 mov.b @(0, r12), r0 85 cmp/eq #0x80, r0 86 bf next_part 87 88 /* found bootable partition */ 89 mov.w @(8, r12), r0 /* load unaligned 32bit data */ 90 mov r0, r1 91 mov.w @(10, r12), r0 92 extu.w r1, r1 93 shll16 r0 94 or r1, r0 95 96 mov r0, r3 97 mova found_sector, r0 98 bra boot_lba 99 mov.l r3, @r0 100 101 next_part: 102 dt r8 103 bf/s loop_part 104 add #16, r12 105 106 noos_error: 107 /* Not found bootable partition */ 108 mova ERR_NOOS, r0 109 error: 110 bsr message_crlf 111 mov r0, r4 112 99: bra 99b 113 nop 114 115 read_error: 116 bra error 117 mova ERR_READ, r0 118 119 message_crlf: 120 mov #32, r0 121 trapa #0x3f 122 mova crlf, r0 123 mov r0, r4 124 mov #32, r0 125 trapa #0x3f 126 rts 127 nop 128 129 read_sector_lba: 130 mov #1, r7 131 mov #2, r0 132 trapa #0x3f 133 tst r0, r0 134 bf read_error 135 rts 136 nop 137 138 boot_lba: 139 /* read PBR sector */ 140 mova found_sector, r0 141 mov #0x40, r4 142 mov.l @r0, r5 143 bsr read_sector_lba 144 mov r10, r6 145 146 /* flush cache */ 147 mov #0, r4 148 mov #6, r0 149 trapa #0x3f 150 151 /* check signature */ 152 mov.b @(0, r10), r0 153 tst r0, r0 154 bt noos_error /* first byte non-zero */ 155 mov.w magic_offset, r0 156 mov.w @(r0, r10), r1 157 mov.w magic, r2 158 cmp/eq r1, r2 159 bf noos_error /* magic */ 160 161 /* now jump to PBR */ 162 mov r10, r0 163 jmp @r10 164 nop 165 166 167 .align 1 168 mbr_size: .word mbr_end - _C_LABEL(start) 169 .align 1 170 stack_offset: .word 0x1000 171 .align 1 172 part_offset: .word MBR_PART_OFFSET 173 .align 1 174 magic_offset: .word MBR_MAGIC_OFFSET 175 176 .align 2 177 found_sector: .long 0 178 179 #ifndef NO_BANNER 180 .align 2 181 banner: .asciz "\r\nNetBSD MBR boot" 182 #endif 183 .align 2 184 crlf: .asciz "\r\n" 185 186 .align 2 187 ERR_INVPART: .asciz "No active partition" 188 .align 2 189 ERR_READ: .asciz "Disk read error" 190 .align 2 191 ERR_NOOS: .asciz "No operating system" 192 193 194 /* space for mbr_dsn */ 195 . = _C_LABEL(start) + MBR_DSN_OFFSET 196 .long 0 197 198 /* mbr_bootsel_magic */ 199 . = _C_LABEL(start) + MBR_BS_MAGIC_OFFSET 200 .word MBR_BS_MAGIC 201 202 /* 203 * MBR partition table 204 */ 205 . = _C_LABEL(start) + MBR_PART_OFFSET 206 _pbr_part0: 207 .byte 0, 0, 0, 0, 0, 0, 0, 0 208 .byte 0, 0, 0, 0, 0, 0, 0, 0 209 _pbr_part1: 210 .byte 0, 0, 0, 0, 0, 0, 0, 0 211 .byte 0, 0, 0, 0, 0, 0, 0, 0 212 _pbr_part2: 213 .byte 0, 0, 0, 0, 0, 0, 0, 0 214 .byte 0, 0, 0, 0, 0, 0, 0, 0 215 _pbr_part3: 216 .byte 0, 0, 0, 0, 0, 0, 0, 0 217 .byte 0, 0, 0, 0, 0, 0, 0, 0 218 219 . = _C_LABEL(start) + MBR_MAGIC_OFFSET 220 magic: 221 .word MBR_MAGIC 222 mbr_end: 223
Indexes created Tue Oct 14 01:09:49 GMT 2025