27 */ 28 29/* 30 * BIOS disk device handling. 31 * 32 * Ideas and algorithms from: 33 * 34 * - NetBSD libi386/biosdisk.c 35 * - FreeBSD biosboot/disk.c 36 * 37 * XXX Todo: add bad144 support. 38 */ 39 40#include <stand.h> 41 42#include <sys/disklabel.h> 43#include <sys/diskslice.h> 44#include <sys/reboot.h> 45 46#include <stdarg.h> 47 48#include <bootstrap.h> 49#include <btxv86.h> 50#include "libi386.h" 51 52#define BIOSDISK_SECSIZE 512 53#define BUFSIZE (1 * BIOSDISK_SECSIZE) 54#define MAXBDDEV MAXDEV 55 56#define DT_ATAPI 0x10 /* disk type for ATAPI floppies */ 57#define WDMAJOR 0 /* major numbers for devices we frontend for */ 58#define WFDMAJOR 1 59#define FDMAJOR 2 60#define DAMAJOR 4 61 62#ifdef DISK_DEBUG 63# define DEBUG(fmt, args...) printf("%s: " fmt "\n" , __FUNCTION__ , ## args) 64#else 65# define DEBUG(fmt, args...) 66#endif 67 68struct open_disk { 69 int od_dkunit; /* disk unit number */ 70 int od_unit; /* BIOS unit number */ 71 int od_cyl; /* BIOS geometry */ 72 int od_hds; 73 int od_sec; 74 int od_boff; /* block offset from beginning of BIOS disk */ 75 int od_flags; 76#define BD_MODEMASK 0x3 77#define BD_MODEINT13 0x0 78#define BD_MODEEDD1 0x1 79#define BD_MODEEDD3 0x2 80#define BD_FLOPPY (1<<2) 81 struct disklabel od_disklabel; 82 struct dos_partition od_parttab[NDOSPART]; /* XXX needs to grow for extended partitions */ 83#define BD_LABELOK (1<<3) 84#define BD_PARTTABOK (1<<4) 85}; 86 87/* 88 * List of BIOS devices, translation from disk unit number to 89 * BIOS unit number. 90 */ 91static struct bdinfo 92{ 93 int bd_unit; /* BIOS unit number */ 94 int bd_flags; 95 int bd_type; /* BIOS 'drive type' (floppy only) */ 96} bdinfo [MAXBDDEV]; 97static int nbdinfo = 0; 98 99static int bd_getgeom(struct open_disk *od); 100static int bd_read(struct open_disk *od, daddr_t dblk, int blks, caddr_t dest); 101 102static int bd_int13probe(struct bdinfo *bd); 103 104static void bd_printslice(struct open_disk *od, int offset, char *prefix); 105 106static int bd_init(void); 107static int bd_strategy(void *devdata, int flag, daddr_t dblk, size_t size, void *buf, size_t *rsize); 108static int bd_realstrategy(void *devdata, int flag, daddr_t dblk, size_t size, void *buf, size_t *rsize); 109static int bd_open(struct open_file *f, ...); 110static int bd_close(struct open_file *f); 111static void bd_print(int verbose); 112 113struct devsw biosdisk = { 114 "disk", 115 DEVT_DISK, 116 bd_init, 117 bd_strategy, 118 bd_open, 119 bd_close, 120 noioctl, 121 bd_print 122}; 123 124static int bd_opendisk(struct open_disk **odp, struct i386_devdesc *dev); 125static void bd_closedisk(struct open_disk *od); 126static int bd_bestslice(struct dos_partition *dptr); 127 128/* 129 * Translate between BIOS device numbers and our private unit numbers. 130 */ 131int 132bd_bios2unit(int biosdev) 133{ 134 int i; 135 136 DEBUG("looking for bios device 0x%x", biosdev); 137 for (i = 0; i < nbdinfo; i++) { 138 DEBUG("bd unit %d is BIOS device 0x%x", i, bdinfo[i].bd_unit); 139 if (bdinfo[i].bd_unit == biosdev) 140 return(i); 141 } 142 return(-1); 143} 144 145int 146bd_unit2bios(int unit) 147{ 148 if ((unit >= 0) && (unit < nbdinfo)) 149 return(bdinfo[unit].bd_unit); 150 return(-1); 151} 152 153/* 154 * Quiz the BIOS for disk devices, save a little info about them. 155 * 156 * XXX should we be consulting the BIOS equipment list, specifically 157 * the value at 0x475? 158 */ 159static int 160bd_init(void) 161{ 162 int base, unit; 163 164 /* sequence 0, 0x80 */ 165 for (base = 0; base <= 0x80; base += 0x80) { 166 for (unit = base; (nbdinfo < MAXBDDEV); unit++) { 167 bdinfo[nbdinfo].bd_unit = unit; 168 bdinfo[nbdinfo].bd_flags = (unit < 0x80) ? BD_FLOPPY : 0; 169 170 /* XXX add EDD probes */ 171 if (!bd_int13probe(&bdinfo[nbdinfo])) 172 break; 173 174 /* XXX we need "disk aliases" to make this simpler */ 175 printf("BIOS drive %c: is disk%d\n", 176 (unit < 0x80) ? ('A' + unit) : ('C' + unit - 0x80), nbdinfo); 177 nbdinfo++; 178 } 179 } 180 return(0); 181} 182 183/* 184 * Try to detect a device supported by the legacy int13 BIOS 185 */ 186 187static int 188bd_int13probe(struct bdinfo *bd) 189{ 190 191 v86.ctl = V86_FLAGS; 192 v86.addr = 0x13; 193 v86.eax = 0x800; 194 v86.edx = bd->bd_unit; 195 v86int(); 196 197 if (!(v86.efl & 0x1) && /* carry clear */ 198 ((v86.edx & 0xff) > (bd->bd_unit & 0x7f))) { /* unit # OK */ 199 bd->bd_flags |= BD_MODEINT13; 200 bd->bd_type = v86.ebx & 0xff; 201 return(1); 202 } 203 return(0); 204} 205 206/* 207 * Print information about disks 208 */ 209static void 210bd_print(int verbose) 211{ 212 int i, j; 213 char line[80]; 214 struct i386_devdesc dev; 215 struct open_disk *od; 216 struct dos_partition *dptr; 217 218 for (i = 0; i < nbdinfo; i++) { 219 sprintf(line, " disk%d: BIOS drive %c:\n", i, 220 (bdinfo[i].bd_unit < 0x80) ? ('A' + bdinfo[i].bd_unit) : ('C' + bdinfo[i].bd_unit - 0x80)); 221 pager_output(line); 222 223 /* try to open the whole disk */ 224 dev.d_kind.biosdisk.unit = i; 225 dev.d_kind.biosdisk.slice = -1; 226 dev.d_kind.biosdisk.partition = -1; 227 228 if (!bd_opendisk(&od, &dev)) { 229 230 /* Do we have a partition table? */ 231 if (od->od_flags & BD_PARTTABOK) { 232 dptr = &od->od_parttab[0]; 233 234 /* Check for a "truly dedicated" disk */ 235 if ((dptr[3].dp_typ == DOSPTYP_386BSD) && 236 (dptr[3].dp_start == 0) && 237 (dptr[3].dp_size == 50000)) { 238 sprintf(line, " disk%d", i); 239 bd_printslice(od, 0, line); 240 } else { 241 for (j = 0; j < NDOSPART; j++) { 242 switch(dptr[j].dp_typ) { 243 case DOSPTYP_386BSD: 244 sprintf(line, " disk%ds%d", i, j + 1); 245 bd_printslice(od, dptr[j].dp_start, line); 246 break; 247 default: 248 } 249 } 250 251 } 252 } 253 bd_closedisk(od); 254 } 255 } 256} 257 258static void 259bd_printslice(struct open_disk *od, int offset, char *prefix) 260{ 261 char line[80]; 262 u_char buf[BIOSDISK_SECSIZE]; 263 struct disklabel *lp; 264 int i; 265 266 /* read disklabel */ 267 if (bd_read(od, offset + LABELSECTOR, 1, buf)) 268 return; 269 lp =(struct disklabel *)(&buf[0]); 270 if (lp->d_magic != DISKMAGIC) { 271 sprintf(line, "bad disklabel\n"); 272 pager_output(line); 273 return; 274 } 275 276 /* Print partitions */ 277 for (i = 0; i < lp->d_npartitions; i++) { 278 if ((lp->d_partitions[i].p_fstype == FS_BSDFFS) || (lp->d_partitions[i].p_fstype == FS_SWAP) || 279 ((lp->d_partitions[i].p_fstype == FS_UNUSED) && 280 (od->od_flags & BD_FLOPPY) && (i == 0))) { /* Floppies often have bogus fstype, print 'a' */ 281 sprintf(line, " %s%c: %s %.6dMB (%d - %d)\n", prefix, 'a' + i, 282 (lp->d_partitions[i].p_fstype == FS_SWAP) ? "swap" : "FFS", 283 lp->d_partitions[i].p_size / 2048, /* 512-byte sector assumption */ 284 lp->d_partitions[i].p_offset, lp->d_partitions[i].p_offset + lp->d_partitions[i].p_size); 285 pager_output(line); 286 } 287 } 288} 289 290 291/* 292 * Attempt to open the disk described by (dev) for use by (f). 293 * 294 * Note that the philosophy here is "give them exactly what 295 * they ask for". This is necessary because being too "smart" 296 * about what the user might want leads to complications. 297 * (eg. given no slice or partition value, with a disk that is 298 * sliced - are they after the first BSD slice, or the DOS 299 * slice before it?) 300 */ 301static int 302bd_open(struct open_file *f, ...) 303{ 304 va_list ap; 305 struct i386_devdesc *dev; 306 struct open_disk *od; 307 int error; 308 309 va_start(ap, f); 310 dev = va_arg(ap, struct i386_devdesc *); 311 va_end(ap); 312 if ((error = bd_opendisk(&od, dev))) 313 return(error); 314 315 /* 316 * Save our context 317 */ 318 ((struct i386_devdesc *)(f->f_devdata))->d_kind.biosdisk.data = od; 319 DEBUG("open_disk %p, partition at 0x%x", od, od->od_boff); 320 return(0); 321} 322 323static int 324bd_opendisk(struct open_disk **odp, struct i386_devdesc *dev) 325{ 326 struct dos_partition *dptr; 327 struct disklabel *lp; 328 struct open_disk *od; 329 int sector, slice, i; 330 int error; 331 u_char buf[BUFSIZE]; 332 daddr_t pref_slice[4]; 333 334 if (dev->d_kind.biosdisk.unit >= nbdinfo) { 335 DEBUG("attempt to open nonexistent disk"); 336 return(ENXIO); 337 } 338 339 od = (struct open_disk *)malloc(sizeof(struct open_disk)); 340 if (!od) { 341 DEBUG("no memory"); 342 return (ENOMEM); 343 } 344 345 /* Look up BIOS unit number, intialise open_disk structure */ 346 od->od_dkunit = dev->d_kind.biosdisk.unit; 347 od->od_unit = bdinfo[od->od_dkunit].bd_unit; 348 od->od_flags = bdinfo[od->od_dkunit].bd_flags; 349 od->od_boff = 0; 350 error = 0; 351 DEBUG("open '%s', unit 0x%x slice %d partition %c", 352 i386_fmtdev(dev), dev->d_kind.biosdisk.unit, 353 dev->d_kind.biosdisk.slice, dev->d_kind.biosdisk.partition + 'a'); 354 355 /* Get geometry for this open (removable device may have changed) */ 356 if (bd_getgeom(od)) { 357 DEBUG("can't get geometry"); 358 error = ENXIO; 359 goto out; 360 } 361 362 /* 363 * Following calculations attempt to determine the correct value 364 * for d->od_boff by looking for the slice and partition specified, 365 * or searching for reasonable defaults. 366 */ 367 368 /* 369 * Find the slice in the DOS slice table. 370 */ 371 if (bd_read(od, 0, 1, buf)) { 372 DEBUG("error reading MBR"); 373 error = EIO; 374 goto out; 375 } 376 377 /* 378 * Check the slice table magic. 379 */ 380 if ((buf[0x1fe] != 0x55) || (buf[0x1ff] != 0xaa)) { 381 /* If a slice number was explicitly supplied, this is an error */ 382 if (dev->d_kind.biosdisk.slice > 0) { 383 DEBUG("no slice table/MBR (no magic)"); 384 error = ENOENT; 385 goto out; 386 } 387 sector = 0; 388 goto unsliced; /* may be a floppy */ 389 } 390 bcopy(buf + DOSPARTOFF, &od->od_parttab, sizeof(struct dos_partition) * NDOSPART); 391 dptr = &od->od_parttab[0]; 392 od->od_flags |= BD_PARTTABOK; 393 394 /* Is this a request for the whole disk? */ 395 if (dev->d_kind.biosdisk.slice == -1) { 396 sector = 0; 397 goto unsliced; 398 } 399 400 /* Try to auto-detect the best slice; this should always give a slice number */ 401 if (dev->d_kind.biosdisk.slice == 0) 402 dev->d_kind.biosdisk.slice = bd_bestslice(dptr); 403 404 switch (dev->d_kind.biosdisk.slice) { 405 case -1: 406 error = ENOENT; 407 goto out; 408 case 0: 409 sector = 0; 410 goto unsliced; 411 default: 412 break; 413 } 414 415 /* 416 * Accept the supplied slice number unequivocally (we may be looking 417 * at a DOS partition). 418 */ 419 dptr += (dev->d_kind.biosdisk.slice - 1); /* we number 1-4, offsets are 0-3 */ 420 sector = dptr->dp_start; 421 DEBUG("slice entry %d at %d, %d sectors", dev->d_kind.biosdisk.slice - 1, sector, dptr->dp_size); 422 423 /* 424 * If we are looking at a BSD slice, and the partition is < 0, assume the 'a' partition 425 */ 426 if ((dptr->dp_typ == DOSPTYP_386BSD) && (dev->d_kind.biosdisk.partition < 0)) 427 dev->d_kind.biosdisk.partition = 0; 428 429 unsliced: 430 /* 431 * Now we have the slice offset, look for the partition in the disklabel if we have 432 * a partition to start with. 433 * 434 * XXX we might want to check the label checksum. 435 */ 436 if (dev->d_kind.biosdisk.partition < 0) { 437 od->od_boff = sector; /* no partition, must be after the slice */ 438 DEBUG("opening raw slice"); 439 } else { 440 441 if (bd_read(od, sector + LABELSECTOR, 1, buf)) { 442 DEBUG("error reading disklabel"); 443 error = EIO; 444 goto out; 445 } 446 DEBUG("copy %d bytes of label from %p to %p", sizeof(struct disklabel), buf + LABELOFFSET, &od->od_disklabel); 447 bcopy(buf + LABELOFFSET, &od->od_disklabel, sizeof(struct disklabel)); 448 lp = &od->od_disklabel; 449 od->od_flags |= BD_LABELOK; 450 451 if (lp->d_magic != DISKMAGIC) { 452 DEBUG("no disklabel"); 453 error = ENOENT; 454 goto out; 455 } 456 if (dev->d_kind.biosdisk.partition >= lp->d_npartitions) { 457 DEBUG("partition '%c' exceeds partitions in table (a-'%c')", 458 'a' + dev->d_kind.biosdisk.partition, 'a' + lp->d_npartitions); 459 error = EPART; 460 goto out; 461 462 } 463 464 /* Complain if the partition type is wrong */ 465 if ((lp->d_partitions[dev->d_kind.biosdisk.partition].p_fstype == FS_UNUSED) && 466 !(od->od_flags & BD_FLOPPY)) /* Floppies often have bogus fstype */ 467 DEBUG("warning, partition marked as unused"); 468 469 od->od_boff = lp->d_partitions[dev->d_kind.biosdisk.partition].p_offset; 470 } 471 472 out: 473 if (error) { 474 free(od); 475 } else { 476 *odp = od; /* return the open disk */ 477 } 478 return(error); 479} 480 481 482/* 483 * Search for a slice with the following preferences: 484 * 485 * 1: Active FreeBSD slice 486 * 2: Non-active FreeBSD slice 487 * 3: Active FAT/FAT32 slice 488 * 4: non-active FAT/FAT32 slice 489 */ 490#define PREF_FBSD_ACT 0 491#define PREF_FBSD 1 492#define PREF_DOS_ACT 2 493#define PREF_DOS 3 494#define PREF_NONE 4 495 496static int 497bd_bestslice(struct dos_partition *dptr) 498{ 499 int i; 500 int preflevel, pref; 501 502 503 /* 504 * Check for the historically bogus MBR found on true dedicated disks 505 */ 506 if ((dptr[3].dp_typ == DOSPTYP_386BSD) && 507 (dptr[3].dp_start == 0) && 508 (dptr[3].dp_size == 50000)) 509 return(0); 510 511 preflevel = PREF_NONE; 512 pref = -1; 513 514 /* 515 * XXX No support here for 'extended' slices 516 */ 517 for (i = 0; i < NDOSPART; i++) { 518 switch(dptr[i].dp_typ) { 519 case DOSPTYP_386BSD: /* FreeBSD */ 520 if ((dptr[i].dp_flag & 0x80) && (preflevel > PREF_FBSD_ACT)) { 521 pref = i; 522 preflevel = PREF_FBSD_ACT; 523 } else if (preflevel > PREF_FBSD) { 524 pref = i; 525 preflevel = PREF_FBSD; 526 } 527 break; 528 529 case 0x04: /* DOS/Windows */ 530 case 0x06: 531 case 0x0b: 532 case 0x0c: 533 case 0x0e: 534 case 0x63: 535 if ((dptr[i].dp_flag & 0x80) && (preflevel > PREF_DOS_ACT)) { 536 pref = i; 537 preflevel = PREF_DOS_ACT; 538 } else if (preflevel > PREF_DOS) { 539 pref = i; 540 preflevel = PREF_DOS; 541 } 542 break; 543 } 544 } 545 return(pref + 1); /* slices numbered 1-4 */ 546} 547 548 549static int 550bd_close(struct open_file *f) 551{ 552 struct open_disk *od = (struct open_disk *)(((struct i386_devdesc *)(f->f_devdata))->d_kind.biosdisk.data); 553 554 bd_closedisk(od); 555 return(0); 556} 557 558static void 559bd_closedisk(struct open_disk *od) 560{ 561 DEBUG("open_disk %p", od); 562#if 0 563 /* XXX is this required? (especially if disk already open...) */ 564 if (od->od_flags & BD_FLOPPY) 565 delay(3000000); 566#endif 567 free(od); 568} 569 570static int 571bd_strategy(void *devdata, int rw, daddr_t dblk, size_t size, void *buf, size_t *rsize) 572{ 573 struct bcache_devdata bcd; 574 575 bcd.dv_strategy = bd_realstrategy; 576 bcd.dv_devdata = devdata; 577 return(bcache_strategy(&bcd, rw, dblk, size, buf, rsize)); 578} 579 580static int 581bd_realstrategy(void *devdata, int rw, daddr_t dblk, size_t size, void *buf, size_t *rsize) 582{ 583 struct open_disk *od = (struct open_disk *)(((struct i386_devdesc *)devdata)->d_kind.biosdisk.data); 584 int blks; 585#ifdef BD_SUPPORT_FRAGS 586 char fragbuf[BIOSDISK_SECSIZE]; 587 size_t fragsize; 588 589 fragsize = size % BIOSDISK_SECSIZE; 590#else 591 if (size % BIOSDISK_SECSIZE) 592 panic("bd_strategy: %d bytes I/O not multiple of block size", size); 593#endif 594 595 DEBUG("open_disk %p", od); 596 597 if (rw != F_READ) 598 return(EROFS); 599 600 601 blks = size / BIOSDISK_SECSIZE; 602 DEBUG("read %d from %d+%d to %p", blks, od->od_boff, dblk, buf); 603 604 if (rsize) 605 *rsize = 0; 606 if (blks && bd_read(od, dblk + od->od_boff, blks, buf)) { 607 DEBUG("read error"); 608 return (EIO); 609 } 610#ifdef BD_SUPPORT_FRAGS 611 DEBUG("bd_strategy: frag read %d from %d+%d+d to %p", 612 fragsize, od->od_boff, dblk, blks, buf + (blks * BIOSDISK_SECSIZE)); 613 if (fragsize && bd_read(od, dblk + od->od_boff + blks, 1, fragsize)) { 614 DEBUG("frag read error"); 615 return(EIO); 616 } 617 bcopy(fragbuf, buf + (blks * BIOSDISK_SECSIZE), fragsize); 618#endif 619 if (rsize) 620 *rsize = size; 621 return (0); 622} 623 624/* Max number of sectors to bounce-buffer if the request crosses a 64k boundary */ 625#define FLOPPY_BOUNCEBUF 18 626 627static int 628bd_read(struct open_disk *od, daddr_t dblk, int blks, caddr_t dest) 629{ 630 int x, bpc, cyl, hd, sec, result, resid, cnt, retry, maxfer; 631 caddr_t p, xp, bbuf, breg; 632 633 bpc = (od->od_sec * od->od_hds); /* blocks per cylinder */ 634 resid = blks; 635 p = dest; 636 637 /* Decide whether we have to bounce */ 638 if ((od->od_unit < 0x80) && 639 ((VTOP(dest) >> 16) != (VTOP(dest + blks * BIOSDISK_SECSIZE) >> 16))) { 640 641 /* 642 * There is a 64k physical boundary somewhere in the destination buffer, so we have 643 * to arrange a suitable bounce buffer. Allocate a buffer twice as large as we 644 * need to. Use the bottom half unless there is a break there, in which case we 645 * use the top half. 646 */ 647 x = min(FLOPPY_BOUNCEBUF, blks); 648 bbuf = malloc(x * 2 * BIOSDISK_SECSIZE); 649 if (((u_int32_t)VTOP(bbuf) & 0xffff0000) == ((u_int32_t)VTOP(dest + x * BIOSDISK_SECSIZE) & 0xffff0000)) { 650 breg = bbuf; 651 } else { 652 breg = bbuf + x * BIOSDISK_SECSIZE; 653 } 654 maxfer = x; /* limit transfers to bounce region size */ 655 } else { 656 bbuf = NULL; 657 maxfer = 0; 658 } 659 660 while (resid > 0) { 661 x = dblk; 662 cyl = x / bpc; /* block # / blocks per cylinder */ 663 x %= bpc; /* block offset into cylinder */ 664 hd = x / od->od_sec; /* offset / blocks per track */ 665 sec = x % od->od_sec; /* offset into track */ 666 667 /* play it safe and don't cross track boundaries (XXX this is probably unnecessary) */ 668 x = min(od->od_sec - sec, resid); 669 if (maxfer > 0) 670 x = min(x, maxfer); /* fit bounce buffer */ 671 672 /* where do we transfer to? */ 673 xp = bbuf == NULL ? p : breg; 674 675 /* correct sector number for 1-based BIOS numbering */ 676 sec++; 677 678 /* Loop retrying the operation a couple of times. The BIOS may also retry. */ 679 for (retry = 0; retry < 3; retry++) { 680 /* if retrying, reset the drive */ 681 if (retry > 0) { 682 v86.ctl = V86_FLAGS; 683 v86.addr = 0x13; 684 v86.eax = 0; 685 v86.edx = od->od_unit; 686 v86int(); 687 } 688 689 /* build request XXX support EDD requests too */ 690 v86.ctl = V86_FLAGS; 691 v86.addr = 0x13; 692 v86.eax = 0x200 | x; 693 v86.ecx = ((cyl & 0xff) << 8) | ((cyl & 0x300) >> 2) | sec; 694 v86.edx = (hd << 8) | od->od_unit; 695 v86.es = VTOPSEG(xp); 696 v86.ebx = VTOPOFF(xp); 697 v86int(); 698 result = (v86.efl & 0x1); 699 if (result == 0) 700 break; 701 } 702 703 DEBUG("%d sectors from %d/%d/%d to %p (0x%x) %s", x, cyl, hd, sec - 1, p, VTOP(p), result ? "failed" : "ok"); 704 /* BUG here, cannot use v86 in printf because putchar uses it too */ 705 DEBUG("ax = 0x%04x cx = 0x%04x dx = 0x%04x status 0x%x", 706 0x200 | x, ((cyl & 0xff) << 8) | ((cyl & 0x300) >> 2) | sec, (hd << 8) | od->od_unit, (v86.eax >> 8) & 0xff); 707 if (result) { 708 if (bbuf != NULL) 709 free(bbuf); 710 return(-1); 711 } 712 if (bbuf != NULL) 713 bcopy(breg, p, x * BIOSDISK_SECSIZE); 714 p += (x * BIOSDISK_SECSIZE); 715 dblk += x; 716 resid -= x; 717 } 718 719/* hexdump(dest, (blks * BIOSDISK_SECSIZE)); */ 720 if (bbuf != NULL) 721 free(bbuf); 722 return(0); 723} 724 725static int 726bd_getgeom(struct open_disk *od) 727{ 728 729 v86.ctl = V86_FLAGS; 730 v86.addr = 0x13; 731 v86.eax = 0x800; 732 v86.edx = od->od_unit; 733 v86int(); 734 735 if ((v86.efl & 0x1) || /* carry set */ 736 ((v86.edx & 0xff) <= (od->od_unit & 0x7f))) /* unit # bad */ 737 return(1); 738 739 /* convert max cyl # -> # of cylinders */ 740 od->od_cyl = ((v86.ecx & 0xc0) << 2) + ((v86.ecx & 0xff00) >> 8) + 1; 741 /* convert max head # -> # of heads */ 742 od->od_hds = ((v86.edx & 0xff00) >> 8) + 1; 743 od->od_sec = v86.ecx & 0x3f; 744 745 DEBUG("unit 0x%x geometry %d/%d/%d", od->od_unit, od->od_cyl, od->od_hds, od->od_sec); 746 return(0); 747} 748 749/*
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