boot.S revision 1.9
1 | file: boot.S 2 | author: chapuni(webmaster@chapuni.com) 3 | ITOH Yasufumi 4 | 5 | $NetBSD: boot.S,v 1.9 2020/01/18 06:34:30 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 SCSI_ADHOC_BOOTPART 46 47 #define SRAM 0x00ED0000 /* SRAM stat addr */ 48 #define SRAM_MEMSZ (SRAM + 8) /* (L) size of main memory */ 49 #define MINMEM 0x00400000 /* at least 4MB required */ 50 51 #define BOOT_ERROR(s) jbsr boot_error; .asciz s; .even 52 53 .globl _C_LABEL(bootmain) 54 .text 55 ASENTRY_NOPROFILE(start) 56 ASENTRY_NOPROFILE(top) 57 bras _ASM_LABEL(entry0) 58 .ascii "SHARP/" 59 .ascii "X680x0" 60 .word 0x8199,0x94e6,0x82ea,0x82bd 61 .word 0x8e9e,0x82c9,0x82cd,0x8cbb 62 .word 0x8ec0,0x93a6,0x94f0,0x8149 63 .word 0 64 | d4 SCSI ID 65 ASENTRY_NOPROFILE(entry0) 66 moveml %d0-%d7/%a0-%a7,_C_LABEL(startregs) 67 lea TEXTADDR:W,%a5 | set base ptr 68 #define _RELOC(adr) %a5@(((adr)-top):W) 69 #define ASRELOC(var) _RELOC(_ASM_LABEL(var)) 70 #define RELOC(var) _RELOC(_C_LABEL(var)) 71 72 lea RELOC(edata),%a1 73 bra _ASM_LABEL(entry) 74 75 | Disklabel= 404bytes 76 | Since LABELOFFSET in <machine/disklabel.h> is 0x40, 77 | entry must be after 0x000001d4 (0x000f01d4) 78 .org 0x40 79 disklabel: 80 .space 404 81 82 ASENTRY_NOPROFILE(entry) 83 movew #_end-1,%d0 | bss end (low word only) 84 85 | clear out bss (must be <= 64KB) 86 subw %a1,%d0 87 clrbss: clrb %a1@+ 88 dbra %d0,clrbss 89 90 movel %d4,RELOC(ID) | SCSI ID (if booted from SCSI) 91 92 lea 0x00100000,%sp | set system stack 93 lea %a5@,%a1 | set load address 94 | a1 will be used later for IOCS calls 95 96 | we use 68020 instructions, and check MPU beforehand 97 | 98 | here d0.w = -1, and the above "subw a1,d0" = 0x9049, and 99 | if MPU <= 010 loads 0x49, 100 | if MPU >= 020 loads 0x90. 101 | This is a move, not a tst instruction 102 | because pc-relative tsts are not available on 000/010. 103 chkmpu: moveb %pc@(clrbss-chkmpu-2:B,%d0:W:2),%d0 | 103B 02xx 104 jmi mpuok | MC68020 or later 105 BOOT_ERROR("MPU 68000?") 106 mpuok: | XXX check for MMU? 107 108 IOCS(__BOOTINF) 109 lsll #8,%d0 | clear MSByte 110 lsrl #8,%d0 | 111 movel %d0,RELOC(BOOT_INFO) 112 113 | 114 | 0x80...0x8F SASI 115 | 0x90...0x93 Floppy 116 | 0xED0000...0xED3FFE SRAM 117 | others ROM (SCSI?) 118 | 119 movel %d0,%d1 120 clrb %d1 121 tstl %d1 122 jne boot_ram_rom 123 | 124 | SASI or Floppy 125 | 126 movel %d0,%d2 127 andib #0xFC,%d0 128 cmpib #0x90,%d0 129 jne boot_dev_unsupported | boot from SASI? 130 | 131 | Floppy 132 | 133 moveb %d2,%d0 134 andib #0x03,%d0 | drive # (head=0) 135 jbsr check_fd_format 136 moveml %d0-%d1,RELOC(FDSECMINMAX) | min and max sec # 137 lslw #8,%d2 138 moveq #0x70,%d1 139 orw %d2,%d1 | PDA*256 + MODE 140 movel %d1,RELOC(FDMODE) 141 movel %d0,%d2 | read position (first sector) 142 movel #8192,%d3 | read bytes 143 IOCS(__B_READ) 144 jra boot_read_done 145 146 #include "chkfmt.s" 147 148 boot_ram_rom: 149 movel %d0,%d1 150 swap %d1 151 cmpiw #0x00ED,%d1 152 jne boot_SCSI 153 | boot from SRAM? 154 155 boot_dev_unsupported: 156 BOOT_ERROR("unsupported boot device") 157 158 | 159 | volatile void BOOT_ERROR(const char *msg); 160 | print error message, wait for key press and reboot 161 | 162 booterr_msg: .asciz "\r\n\n" 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 ENTRY_NOPROFILE(exit) 174 ENTRY_NOPROFILE(_rtt) 175 lea %pc@(reboot_msg),%a1 176 IOCS(__B_PRINT) 177 178 | wait for a key press (or release of a modifier) 179 IOCS(__B_KEYINP) 180 181 | issue software reset 182 trap #10 183 | NOTREACHED 184 185 186 | 187 | ROM boot ... probably from SCSI 188 | 189 boot_SCSI: 190 #ifdef SCSI_ADHOC_BOOTPART 191 | 192 | Find out boot partition in an ad hoc manner. 193 | 194 195 | get block length of the SCSI disk 196 SCSIIOCS(__S_READCAP) | using buffer at a1 197 tstl %d0 198 jeq 1f 199 BOOT_ERROR("READCAP failed") 200 1: moveq #0,%d5 201 moveb %a1@(6),%d5 | 1: 256, 2: 512, 4: 1024, 8: 2048 202 lsrb #1,%d5 | 0: 256, 1: 512, 2: 1024, 4: 2048 203 movel %d5,RELOC(SCSI_BLKLEN) 204 205 | find out the start position of the boot partition 206 | XXX VERY AD HOC 207 | 208 | ROM firmware: 209 | pass read pos (in block #) in d2 210 | Human68k-style partition table does not exist 211 | d2 is 4 at the maximum 212 | SCSI IPLs (genuine and SxSI): 213 | pass read pos (in kilobytes) in d2 214 | d2 is bigger than 0x20 215 | partition table on the memory is destroyed 216 | BOOT MENU Ver.2.22: 217 | passes partition table entry address in a0 218 | d2 is cleared to zero 219 | No other IPL is supported. XXX FIXME 220 tstl %d2 221 jne sc1 222 | no information in d2 -- probably from BOOT MENU 223 | a0 points the partiion table entry 224 movel %a0@(0x0008),%d2 | in KByte 225 sc1: cmpl #0x20,%d2 226 jcs sc2 227 lsll #8,%d2 | clear MSByte 228 lsrl #7,%d2 | in 512 byte block 229 divul %d5,%d2 | in sector 230 sc2: 231 | read entire boot 232 moveq #TDSIZE/512,%d3 | size is TDSIZE byte 233 divul %d5,%d3 | in sector 234 jbsr scsiread | read at %a1 235 236 cmpil #5,%d2 237 bcc sc3 238 movql #0,%d2 239 sc3: movel %d2,RELOC(SCSI_PARTTOP) 240 #else 241 moveq #1,%d5 | 512bytes/sec 242 movel %d5,%sp@- 243 moveq #8192/512,%d3 | 244 moveq #0x40,%d2 | (sd*a ) 245 SCSIIOCS(__S_READ) 246 #endif 247 248 boot_read_done: 249 jmp first_kbyte 250 251 read_error: BOOT_ERROR("read error") 252 253 #undef RELOC /* base register a5 is no longer available */ 254 #undef ASRELOC 255 #undef _RELOC 256 257 | 258 | read SCSI 259 | 260 | input: d2.l: pos in sector 261 | d3.l: len in sector 262 | d4: target SCSI ID 263 | d5: sector length (1: 512, 2: 1024, 4: 2048) 264 | a1: buffer address 265 | destroy: 266 | d0, d1, a1 267 | 268 scsiread: 269 moveml %d2-%d3/%d6-%d7/%a2,%sp@- 270 | if (pos >= 0x200000 || (len > 255 && pos + len >= 0x200000)) 271 | use READEXT 272 | else 273 | use READ 274 moveq #0x20,%d0 275 swap %d0 | d0.l = 0x00200000 276 moveq #0,%d6 277 subqb #1,%d6 | d6.l = 255 278 movel %d5,%d7 279 lsll #8,%d7 280 lsll #1,%d7 | d7 = sector length (byte) 281 cmpl %d0,%d2 282 jcc scsiread_ext 283 moveq #__S_READ,%d1 284 cmpl %d3,%d6 285 jcc scsiread_noext 286 subl %d2,%d0 | d0.0 = 0x200000 - pos 287 cmpl %d0,%d3 | <= len 288 jcs scsiread_noext | no 289 290 scsiread_ext: | use READEXT 291 extw %d6 | d6.l = 65535 292 moveq #__S_READEXT,%d1 293 294 scsiread_noext: | use READ 295 loop_scsiread: 296 | d1: SCSI IOCS call # 297 | d6: max sector count at a time 298 movel %d3,%a2 | save original len in a2 299 cmpl %d3,%d6 300 jcc 1f 301 movel %d6,%d3 302 1: IOCS(__SCSIDRV) | SCSIIOCS(d1) 303 tstl %d0 304 jne read_error 305 movel %d3,%d0 306 mulul %d7,%d0 307 addl %d0,%a1 308 exg %d3,%a2 | restore original len to d3 309 addl %a2,%d2 | pos += read count 310 subl %a2,%d3 | len -= read count 311 jne loop_scsiread 312 moveml %sp@+,%d2-%d3/%d6-%d7/%a2 313 rts 314 315 | 316 | The former part must reside in the first 1KB. 317 | 318 .globl first_kbyte 319 first_kbyte: 320 |-------------------------------------------------------------------------- 321 | 322 | The latter text+data part is not accessible at the first boot time. 323 | PC-relative can be used from here. 324 | 325 | Initialize the screen here. Some IPL (060turbo ROM or 326 | genuine boot selector) don't initialize the screen. 327 | Such initialization should be done as early as possible 328 | but it's too severe to place it in first_kbyte area. 329 | Therefore do it here. 330 moveq #0x10,%d1 331 IOCS(__CRTMOD) 332 333 jmp _C_LABEL(bootmain) | 0x0Fxxxx 334 335 .word 0 336 337 | int badbaddr __P((void *adr)); 338 | check if the given address is valid for byte read 339 | return: 0: valid, 1: not valid 340 341 ENTRY_NOPROFILE(badbaddr) 342 lea 0x0008:W,%a1 | MPU Bus Error vector 343 moveq #1,%d0 344 lea %pc@(badr1),%a0 345 movew %sr,%sp@- 346 oriw #0x0700,%sr | keep out interrupts 347 movel %a1@,%sp@- 348 movel %a0,%a1@ | set bus error vector 349 movel %sp,%d1 | save sp 350 moveal %sp@(10),%a0 351 tstb %a0@ | try read... 352 moveq #0,%d0 | this is skipped on bus error 353 badr1: moveal %d1,%sp | restore sp 354 movel %sp@+,%a1@ 355 movew %sp@+,%sr 356 rts 357 358 | void RAW_READ __P((void *buf, u_int32_t blkpos, size_t bytelen)); 359 | inputs: 360 | buf: input buffer address 361 | blkpos: read start position in the partition in 512byte-blocks 362 | bytelen: read length in bytes 363 364 Lraw_read_buf=4+(4*11) 365 Lraw_read_pos_=Lraw_read_buf+4 366 Lraw_read_len=Lraw_read_buf+8 367 368 #ifdef SCSI_ADHOC_BOOTPART 369 | RAW_READ of physical disk 370 ENTRY_NOPROFILE(RAW_READ0) 371 moveq #0,%d0 372 jra raw_read1 373 #endif 374 375 ENTRY_NOPROFILE(RAW_READ) 376 #ifdef SCSI_ADHOC_BOOTPART 377 movel _C_LABEL(SCSI_PARTTOP),%d0 378 raw_read1: 379 #endif 380 moveml %d2-%d7/%a2-%a6,%sp@- 381 moveml %sp@(Lraw_read_buf),%d1-%d3 382 movel %d1,%a1 383 | d2.l: pos in 512byte-blocks 384 | d3.l: length in bytes 385 | a1 (=d1): buffer address 386 387 lea TEXTADDR:W,%a5 | set base ptr 388 #define _RELOC(adr) %a5@(((adr)-top):W) 389 #define ASRELOC(var) _RELOC(_ASM_LABEL(var)) 390 #define RELOC(var) _RELOC(_C_LABEL(var)) 391 392 tstb _RELOC(_C_LABEL(BOOT_INFO)+1) | simple check. may be incorrect! 393 beqs raw_read_floppy 394 395 raw_read_scsi: 396 movel RELOC(ID),%d4 | SCSI ID 397 #ifdef SCSI_ADHOC_BOOTPART 398 movel RELOC(SCSI_BLKLEN),%d5 | sector size: 0-2 399 | XXX length must be sector aligned 400 lsrl #8,%d3 | size in 256byte-blocks 401 lsrl #1,%d3 402 divul %d5,%d3 | size in sector 403 beqs read_half | minimal error check 404 divul %d5,%d2 | pos in sector 405 addl %d0,%d2 | physical pos in sector 406 #else 407 moveq #1,%d5 | 512bytes/sec 408 moveq #9,%d0 | shift count 409 addl #511,%d3 410 lsrl %d0,%d3 411 bcss read_half | minimal error check 412 413 addl #0x40,%d2 | 'a' partition starts here 414 #endif 415 | jcc 1f 416 | BOOT_ERROR("out of seek") | pos exceeds 32bit 417 |1: 418 jbsr scsiread 419 bras raw_read_end 420 421 raw_read_floppy: 422 | 423 | Floppy read routine 424 | 425 426 | convert to seek position 427 428 asll #2,%d2 | size in 128byte-blocks 429 430 | sec = raw_read_pos (d2) 431 | sec >>= 7 + (sector length: 0-3) 432 433 lea RELOC(FDSECMINMAX),%a0 434 moveq #0,%d1 435 moveb %a0@,%d1 | d1: sector length (0-3) 436 lsrl %d1,%d2 | d2: pos in sector 437 bcss read_half | error check 438 439 | trk = sec / (# sectors) 440 | sec = sec % (# sectors) 441 442 moveb %a0@(7),%d1 | d1: max sector # 443 subb %a0@(3),%d1 | - min sector # 444 addqb #1,%d1 | d1: # sectors 445 divu %d1,%d2 | d2: (sec << 16) | track 446 447 | position = (sec length << 24) | (track/2 << 16) 448 | | (track%2 << 8) | (min sec # + sec) 449 450 movel %a0@,%d0 | d0: (sec len << 24) | min sec # 451 lsrw #1,%d2 | d2: (sec << 16) | (track / 2) 452 jcc 1f 453 bset #8,%d0 | |= (track % 2) << 8 454 1: swap %d2 | d2: ((track / 2) << 16) | sec 455 addl %d0,%d2 | d2: position 456 457 | read 458 movel RELOC(FDMODE),%d1 | PDA*256 + MODE 459 460 | B_READ (for floppy) 461 | d1.w: PDA x 256 + MODE 462 | PDA: 0x90 (drive 0) ... 0x93 (drive 3) 463 | MODE: bit6: MFM 464 | bit5: retry 465 | bit4: seek 466 | d2.l: position 467 | bit31-24: sector length (0: 128, 1: 256, 2: 512, 3: 1K) 468 | bit23-16: track # (0-79) 469 | bit15-08: side (0 or 1) 470 | bit07-00: sector # (1-) 471 | d3.l: read bytes 472 | a1: read address 473 | return: 474 | d0: bit 31-24 ST0 475 | bit 23-16 ST1 476 | bit 15- 8 ST2 477 | bit 7- 0 C 478 | -1 on parameter error 479 | destroy: d0, d2, d3, a1 480 IOCS(__B_READ) 481 andil #0xf8ffff00,%d0 | check status (must be zero) 482 jne read_error 483 484 raw_read_end: 485 moveml %sp@+,%a2-%a6/%d2-%d7 486 rts 487 #undef _RELOC /* base register a5 is no longer available */ 488 #undef ASRELOC 489 #undef RELOC 490 491 read_half: BOOT_ERROR("read half of block") 492 493 494 | 495 | global variables 496 | 497 BSS(ID, 4) | SCSI ID 498 BSS(BOOT_INFO, 4) | result of IOCS(__BOOTINF) 499 BSS(FDMODE, 4) | Floppy access mode: PDA x 256 + MODE 500 BSS(FDSECMINMAX, 8) | +0: (min sector) sector length 501 | +1: (min sector) track # 502 | +2: (min sector) side 503 | +3: (min sector) sector # 504 | +4: (max sector) sector length 505 | +5: (max sector) track # 506 | +6: (max sector) side 507 | +7: (max sector) sector # 508 #ifdef SCSI_ADHOC_BOOTPART 509 BSS(SCSI_PARTTOP, 4) | start sector of boot partition 510 BSS(SCSI_BLKLEN ,4) | sector len 0: 256, 1: 512, 2: 1024 511 #endif 512
Indexes created Wed Oct 22 13:09:56 GMT 2025