boot.S revision 1.18
1 | file: boot.S 2 | author: chapuni(webmaster@chapuni.com) 3 | ITOH Yasufumi 4 | 5 | $NetBSD: boot.S,v 1.18 2020/01/28 11:52:21 isaki Exp $ 6 7 | 8 | (1) IPL (or previous stage loader) loads first 1KB of this primary 9 | bootloader to (*). (*) is 0x2000 (from FD) or 0x2400 (from SASI/SCSI). 10 | 11 | (2) The first 1KB loads full primary bootloader (including first 1KB) from 12 | the boot partition to 0x3000. And jump to there. 13 | 14 | (3) The full primary bootloader loads the secondary bootloader known as 15 | /boot from its filesystem to 0x6000. And jump to there. 16 | 17 | Therefore, The first 1KB must be relocatable. 18 | The first 1KB must be smaller than or equal to 1024 bytes. 19 | 20 | (1) -> (2) -> (3) 21 | +------------+ +------------+ +------------+ 0x000000 22 | : : : : : : 23 | +------------+ +------------+ +------------+ (*) 24 | | first 1KB | | first 1KB | | first 1KB | 25 | +------------+ +------------+ +------------+ (*)+0x400 26 | : : : : : : 27 | : : +------------+ +------------+ 0x003000 28 | : : |full primary| |full primary| 29 | : : |boot loader | |boot loader | 30 | : : +------------+ +------------+ 31 | : : : : : : 32 | : : : : +------------+ 0x006000 33 | : : : : | /boot | 34 | : : : : +------------+ 35 | : : : : : : 36 | ~ ~ ~ ~ ~ ~ 37 | : : : :<-SP : :<-SP 38 | + - - - - - -+ + - - - - - -+ + - - - - - -+ 0x100000 39 | : : : : : : 40 | 41 42 #include <machine/asm.h> 43 #include "iocscall.h" 44 45 #define SRAM 0x00ED0000 /* SRAM stat addr */ 46 #define SRAM_MEMSZ (SRAM + 8) /* (L) size of main memory */ 47 #define MINMEM 0x00400000 /* at least 4MB required */ 48 49 #define BOOT_ERROR(s) jbsr boot_error; .asciz s; .even 50 51 .globl _C_LABEL(bootufs) 52 .text 53 ASENTRY_NOPROFILE(start) 54 ASENTRY_NOPROFILE(top) 55 bras _ASM_LABEL(entry0) 56 .ascii "SHARP/" 57 .ascii "X680x0" 58 .word 0x8199,0x94e6,0x82ea,0x82bd 59 .word 0x8e9e,0x82c9,0x82cd,0x8cbb 60 .word 0x8ec0,0x93a6,0x94f0,0x8149 61 .word 0 62 | d4 SCSI ID 63 ASENTRY_NOPROFILE(entry0) 64 moveml %d0-%d7/%a0-%a7,_C_LABEL(startregs) 65 lea TEXTADDR:W,%a5 | set base ptr 66 #define _RELOC(adr) %a5@(((adr)-top):W) 67 #define ASRELOC(var) _RELOC(_ASM_LABEL(var)) 68 #define RELOC(var) _RELOC(_C_LABEL(var)) 69 70 lea RELOC(__bss_start),%a1 71 bra _ASM_LABEL(entry) 72 73 | Disklabel= 404bytes 74 | Since LABELOFFSET in <machine/disklabel.h> is 0x40, 75 | entry must be after 0x000001d4 (0x000f01d4) 76 .org 0x40 77 disklabel: 78 .space 404 79 80 ASENTRY_NOPROFILE(entry) 81 movew #_end-1,%d0 | bss end (low word only) 82 83 | clear out bss (must be <= 64KB) 84 subw %a1,%d0 85 clrbss: clrb %a1@+ 86 dbra %d0,clrbss 87 88 movel %d4,RELOC(ID) | SCSI ID (if booted from SCSI) 89 90 lea 0x00100000,%sp | set system stack 91 lea %a5@,%a1 | set load address 92 | a1 will be used later for IOCS calls 93 94 | we use 68020 instructions, and check MPU beforehand 95 | 96 | here d0.w = -1, and the above "subw a1,d0" = 0x9049, and 97 | if MPU <= 010 loads 0x49, 98 | if MPU >= 020 loads 0x90. 99 | This is a move, not a tst instruction 100 | because pc-relative tsts are not available on 000/010. 101 chkmpu: moveb %pc@(clrbss-chkmpu-2:B,%d0:W:2),%d0 | 103B 02xx 102 jmi mpuok | MC68020 or later 103 BOOT_ERROR("MPU 68000?") 104 mpuok: | XXX check for MMU? 105 106 IOCS(__BOOTINF) 107 lsll #8,%d0 | clear MSByte 108 lsrl #8,%d0 | 109 movel %d0,RELOC(BOOT_INFO) 110 111 | 112 | 0x80...0x8F SASI 113 | 0x90...0x93 Floppy 114 | 0xED0000...0xED3FFE SRAM 115 | others ROM (SCSI?) 116 | 117 movel %d0,%d1 118 clrb %d1 119 tstl %d1 120 jne boot_ram_rom 121 | 122 | SASI or Floppy 123 | 124 movel %d0,%d2 125 andib #0xFC,%d0 126 cmpib #0x90,%d0 127 jne boot_dev_unsupported | boot from SASI? 128 | 129 | Floppy 130 | 131 moveb %d2,%d0 132 andib #0x03,%d0 | drive # (head=0) 133 jbsr check_fd_format 134 moveml %d0-%d1,RELOC(FDSECMINMAX) | min and max sec # 135 lslw #8,%d2 136 moveq #0x70,%d1 137 orw %d2,%d1 | PDA*256 + MODE 138 movel %d1,RELOC(FDMODE) 139 movel %d0,%d2 | read position (first sector) 140 movel #8192,%d3 | read bytes 141 IOCS(__B_READ) 142 jra boot_read_done 143 144 #include "chkfmt.s" 145 146 boot_ram_rom: 147 movel %d0,%d1 148 swap %d1 149 cmpiw #0x00ED,%d1 150 jne boot_SCSI 151 | boot from SRAM? 152 153 boot_dev_unsupported: 154 BOOT_ERROR("unsupported boot device") 155 156 | 157 | volatile void BOOT_ERROR(const char *msg); 158 | print error message, wait for key press and reboot 159 | 160 booterr_msg: .ascii "\r\n\n" 161 .ascii BOOT 162 .asciz ": " 163 reboot_msg: .asciz "\r\n[Hit key to reboot]" 164 .even 165 166 ENTRY_NOPROFILE(BOOT_ERROR) 167 addql #4,%sp 168 169 boot_error: lea %pc@(booterr_msg),%a1 170 IOCS(__B_PRINT) 171 moveal %sp@+,%a1 172 IOCS(__B_PRINT) 173 lea %pc@(reboot_msg),%a1 174 IOCS(__B_PRINT) 175 176 | wait for a key press (or release of a modifier) 177 IOCS(__B_KEYINP) 178 179 | issue software reset 180 trap #10 181 | NOTREACHED 182 183 184 | 185 | ROM boot ... probably from SCSI 186 | 187 boot_SCSI: 188 #ifdef SCSI_ADHOC_BOOTPART 189 | 190 | Find out boot partition in an ad hoc manner. 191 | 192 193 | get block length of the SCSI disk 194 SCSIIOCS(__S_READCAP) | using buffer at a1 195 tstl %d0 196 jeq 1f 197 BOOT_ERROR("READCAP failed") 198 1: moveq #0,%d5 199 moveb %a1@(6),%d5 | 1: 256, 2: 512, 4: 1024 200 lsrb #1,%d5 | 0: 256, 1: 512, 2: 1024 201 movel %d5,RELOC(SCSI_BLKLEN) 202 203 | find out the start position of the boot partition 204 | XXX VERY AD HOC 205 | 206 | ROM firmware: 207 | pass read pos (in block #) in d2 208 | Human68k-style partition table does not exist 209 | d2 is 4 at the maximum 210 | SCSI IPLs (genuine and SxSI): 211 | pass read pos (in kilobytes) in d2 212 | d2 is bigger than 0x20 213 | partition table on the memory is destroyed 214 | BOOT MENU Ver.2.22: 215 | passes partition table entry address in a0 216 | d2 is cleared to zero 217 | No other IPL is supported. XXX FIXME 218 tstl %d2 219 jne sc1 220 | no information in d2 -- probably from BOOT MENU 221 | a0 points the partiion table entry 222 movel %a0@(0x0008),%d2 | in KByte 223 sc1: cmpl #0x20,%d2 224 jcs sc2 225 lsll #8,%d2 | clear MSByte 226 lsrl #6,%d2 | 227 lsrl %d5,%d2 | in sector 228 sc2: 229 | read entire boot 230 moveq #8192/256,%d3 | size is 8KB 231 lsrl %d5,%d3 | in sector 232 jbsr scsiread | read at %a1 233 234 cmpil #5,%d2 235 bcc sc3 236 movql #0,%d2 237 sc3: movel %d2,RELOC(SCSI_PARTTOP) 238 #else 239 moveq #1,%d5 | 512bytes/sec 240 movel %d5,%sp@- 241 moveq #8192/512,%d3 | 242 moveq #0x40,%d2 | (sd*a ) 243 SCSIIOCS(__S_READ) 244 #endif 245 246 boot_read_done: 247 jmp first_kbyte 248 249 read_error: BOOT_ERROR("read error") 250 251 #undef RELOC /* base register a5 is no longer available */ 252 #undef ASRELOC 253 #undef _RELOC 254 255 | 256 | read SCSI 257 | 258 | input: d2.l: pos in sector 259 | d3.l: len in sector 260 | d4: target SCSI ID 261 | d5: sector length (0: 256, 1: 512, 2: 1024) 262 | a1: buffer address 263 | destroy: 264 | d0, d1, a1 265 | 266 scsiread: 267 moveml %d2-%d3/%d6-%d7/%a2,%sp@- 268 | if (pos >= 0x200000 || (len > 255 && pos + len >= 0x200000)) 269 | use READEXT 270 | else 271 | use READ 272 moveq #0x20,%d0 273 swap %d0 | d0.l = 0x00200000 274 moveq #0,%d6 275 subqb #1,%d6 | d6.l = 255 276 moveq #8,%d7 277 addb %d5,%d7 | d7.b = (sector length: 0-2) + 8 278 cmpl %d0,%d2 279 jcc scsiread_ext 280 moveq #__S_READ,%d1 281 cmpl %d3,%d6 282 jcc scsiread_noext 283 subl %d2,%d0 | d0.0 = 0x200000 - pos 284 cmpl %d0,%d3 | <= len 285 jcs scsiread_noext | no 286 287 scsiread_ext: | use READEXT 288 extw %d6 | d6.l = 65535 289 moveq #__S_READEXT,%d1 290 291 scsiread_noext: | use READ 292 loop_scsiread: 293 | d1: SCSI IOCS call # 294 | d6: max sector count at a time 295 movel %d3,%a2 | save original len in a2 296 cmpl %d3,%d6 297 jcc 1f 298 movel %d6,%d3 299 1: IOCS(__SCSIDRV) | SCSIIOCS(d1) 300 tstl %d0 301 jne read_error 302 movel %d3,%d0 | addr += read count << (8 + sec len) 303 asll %d7,%d0 304 addl %d0,%a1 305 exg %d3,%a2 | restore original len to d3 306 addl %a2,%d2 | pos += read count 307 subl %a2,%d3 | len -= read count 308 jne loop_scsiread 309 moveml %sp@+,%d2-%d3/%d6-%d7/%a2 310 rts 311 312 | 313 | The former part must reside in the first 1KB. 314 | 315 .globl first_kbyte 316 first_kbyte: 317 |-------------------------------------------------------------------------- 318 | 319 | The latter text+data part is not accessible at the first boot time. 320 | PC-relative can be used from here. 321 | 322 | Initialize the screen here. Some IPL (060turbo ROM or 323 | genuine boot selector) don't initialize the screen. 324 | Such initialization should be done as early as possible 325 | but it's too severe to place it in first_kbyte area. 326 | Therefore do it here. 327 moveq #0x10,%d1 328 IOCS(__CRTMOD) 329 330 jmp _C_LABEL(bootufs) | 0x0Fxxxx 331 332 .word 0 333 334 | int badbaddr __P((void *adr)); 335 | check if the given address is valid for byte read 336 | return: 0: valid, 1: not valid 337 338 ENTRY_NOPROFILE(badbaddr) 339 lea 0x0008:W,%a1 | MPU Bus Error vector 340 moveq #1,%d0 341 lea %pc@(badr1),%a0 342 movew %sr,%sp@- 343 oriw #0x0700,%sr | keep out interrupts 344 movel %a1@,%sp@- 345 movel %a0,%a1@ | set bus error vector 346 movel %sp,%d1 | save sp 347 moveal %sp@(10),%a0 348 tstb %a0@ | try read... 349 moveq #0,%d0 | this is skipped on bus error 350 badr1: moveal %d1,%sp | restore sp 351 movel %sp@+,%a1@ 352 movew %sp@+,%sr 353 rts 354 355 | void RAW_READ __P((void *buf, u_int32_t blkpos, size_t bytelen)); 356 | inputs: 357 | buf: input buffer address 358 | blkpos: read start position in the partition in 512byte-blocks 359 | bytelen: read length in bytes 360 361 Lraw_read_buf=4+(4*11) 362 Lraw_read_pos_=Lraw_read_buf+4 363 Lraw_read_len=Lraw_read_buf+8 364 365 #ifdef SCSI_ADHOC_BOOTPART 366 | RAW_READ of physical disk 367 ENTRY_NOPROFILE(RAW_READ0) 368 moveq #0,%d0 369 jra raw_read1 370 #endif 371 372 ENTRY_NOPROFILE(RAW_READ) 373 #ifdef SCSI_ADHOC_BOOTPART 374 movel _C_LABEL(SCSI_PARTTOP),%d0 375 raw_read1: 376 #endif 377 moveml %d2-%d7/%a2-%a6,%sp@- 378 moveml %sp@(Lraw_read_buf),%d1-%d3 379 movel %d1,%a1 380 | d2.l: pos in 512byte-blocks 381 | d3.l: length in bytes 382 | a1 (=d1): buffer address 383 384 lea TEXTADDR:W,%a5 | set base ptr 385 #define _RELOC(adr) %a5@(((adr)-top):W) 386 #define ASRELOC(var) _RELOC(_ASM_LABEL(var)) 387 #define RELOC(var) _RELOC(_C_LABEL(var)) 388 389 tstb _RELOC(_C_LABEL(BOOT_INFO)+1) | simple check. may be incorrect! 390 beqs raw_read_floppy 391 392 raw_read_scsi: 393 movel RELOC(ID),%d4 | SCSI ID 394 #ifdef SCSI_ADHOC_BOOTPART 395 movel RELOC(SCSI_BLKLEN),%d5 | sector size: 0-2 396 | XXX length must be sector aligned 397 lsrl #8,%d3 | size in 256byte-blocks 398 lsrl %d5,%d3 | size in sector 399 bcss read_half | minimal error check 400 lsll #1,%d2 | X flag and d2: pos in 256byte-blocks 401 roxrl %d5,%d2 | pos in sector 402 addl %d0,%d2 | physical pos in sector 403 #else 404 moveq #1,%d5 | 512bytes/sec 405 moveq #9,%d0 | shift count 406 addl #511,%d3 407 lsrl %d0,%d3 408 bcss read_half | minimal error check 409 410 addl #0x40,%d2 | 'a' partition starts here 411 #endif 412 | jcc 1f 413 | BOOT_ERROR("out of seek") | pos exceeds 32bit 414 |1: 415 jbsr scsiread 416 bras raw_read_end 417 418 raw_read_floppy: 419 | 420 | Floppy read routine 421 | 422 423 | convert to seek position 424 425 asll #2,%d2 | size in 128byte-blocks 426 427 | sec = raw_read_pos (d2) 428 | sec >>= 7 + (sector length: 0-3) 429 430 lea RELOC(FDSECMINMAX),%a0 431 moveq #0,%d1 432 moveb %a0@,%d1 | d1: sector length (0-3) 433 lsrl %d1,%d2 | d2: pos in sector 434 bcss read_half | error check 435 436 | trk = sec / (# sectors) 437 | sec = sec % (# sectors) 438 439 moveb %a0@(7),%d1 | d1: max sector # 440 subb %a0@(3),%d1 | - min sector # 441 addqb #1,%d1 | d1: # sectors 442 divu %d1,%d2 | d2: (sec << 16) | track 443 444 | position = (sec length << 24) | (track/2 << 16) 445 | | (track%2 << 8) | (min sec # + sec) 446 447 movel %a0@,%d0 | d0: (sec len << 24) | min sec # 448 lsrw #1,%d2 | d2: (sec << 16) | (track / 2) 449 jcc 1f 450 bset #8,%d0 | |= (track % 2) << 8 451 1: swap %d2 | d2: ((track / 2) << 16) | sec 452 addl %d0,%d2 | d2: position 453 454 | read 455 movel RELOC(FDMODE),%d1 | PDA*256 + MODE 456 457 | B_READ (for floppy) 458 | d1.w: PDA x 256 + MODE 459 | PDA: 0x90 (drive 0) ... 0x93 (drive 3) 460 | MODE: bit6: MFM 461 | bit5: retry 462 | bit4: seek 463 | d2.l: position 464 | bit31-24: sector length (0: 128, 1: 256, 2: 512, 3: 1K) 465 | bit23-16: track # (0-79) 466 | bit15-08: side (0 or 1) 467 | bit07-00: sector # (1-) 468 | d3.l: read bytes 469 | a1: read address 470 | return: 471 | d0: bit 31-24 ST0 472 | bit 23-16 ST1 473 | bit 15- 8 ST2 474 | bit 7- 0 C 475 | -1 on parameter error 476 | destroy: d0, d2, d3, a1 477 IOCS(__B_READ) 478 andil #0xf8ffff00,%d0 | check status (must be zero) 479 jne read_error 480 481 raw_read_end: 482 moveml %sp@+,%a2-%a6/%d2-%d7 483 rts 484 #undef _RELOC /* base register a5 is no longer available */ 485 #undef ASRELOC 486 #undef RELOC 487 488 read_half: BOOT_ERROR("read half of block") 489 490 491 ENTRY_NOPROFILE(B_PUTC) 492 movel %sp@(4),%d1 493 IOCS(__B_PUTC) 494 rts 495 496 ENTRY_NOPROFILE(B_PRINT) 497 movel %sp@(4),%a1 498 IOCS(__B_PRINT) 499 rts 500 501 | 502 | void memcpy(void *dst, const void *src, size_t count); 503 | void memmove(void *dst, const void *src, size_t count); 504 | 505 | small and slow memcpy... 506 | THIS FUNCTION DOES NOT CONFORM THE ANSI STANDARD 507 | 508 ENTRY_NOPROFILE(memcpy) 509 ENTRY_NOPROFILE(memmove) 510 lea %sp@(12),%a1 511 movel %a1@,%d1 | count 512 jeq Lmcpret 513 moveal %a1@-,%a0 | src 514 moveal %a1@-,%a1 | dest 515 cmpl %a1,%a0 516 jcc Lmcpfw 517 | copy backward 518 addal %d1,%a0 519 addal %d1,%a1 520 1: moveb %a0@-,%a1@- 521 subql #1,%d1 522 jne 1b 523 jra Lmcpret 524 Lmcpfw: | copy forward 525 1: moveb %a0@+,%a1@+ 526 subql #1,%d1 527 jne 1b 528 Lmcpret: 529 | movel %sp@(8),%d0 | uncomment this to conform ANSI 530 rts 531 532 533 | 534 | global variables 535 | 536 BSS(ID, 4) | SCSI ID 537 BSS(BOOT_INFO, 4) | result of IOCS(__BOOTINF) 538 BSS(FDMODE, 4) | Floppy access mode: PDA x 256 + MODE 539 BSS(FDSECMINMAX, 8) | +0: (min sector) sector length 540 | +1: (min sector) track # 541 | +2: (min sector) side 542 | +3: (min sector) sector # 543 | +4: (max sector) sector length 544 | +5: (max sector) track # 545 | +6: (max sector) side 546 | +7: (max sector) sector # 547 #ifdef SCSI_ADHOC_BOOTPART 548 BSS(SCSI_PARTTOP, 4) | start sector of boot partition 549 BSS(SCSI_BLKLEN ,4) | sector len 0: 256, 1: 512, 2: 1024 550 #endif 551
Indexes created Thu Oct 02 10:09:58 GMT 2025