usr/src/boot/sys/boot/i386/libi386/biosdisk.c

   1 /*-
   2  * Copyright (c) 1998 Michael Smith <msmith@freebsd.org>
   3  * Copyright (c) 2012 Andrey V. Elsukov <ae@FreeBSD.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27
  28 #include <sys/cdefs.h>
  29
  30 /*
  31  * BIOS disk device handling.
  32  *
  33  * Ideas and algorithms from:
  34  *
  35  * - NetBSD libi386/biosdisk.c
  36  * - FreeBSD biosboot/disk.c
  37  *
  38  */
  39
  40 #include <sys/disk.h>
  41 #include <sys/limits.h>
  42 #include <stand.h>
  43 #include <machine/bootinfo.h>
  44 #include <stdarg.h>
  45
  46 #include <bootstrap.h>
  47 #include <btxv86.h>
  48 #include <edd.h>
  49 #include "disk.h"
  50 #include "libi386.h"
  51
  52 CTASSERT(sizeof(struct i386_devdesc) >= sizeof(struct disk_devdesc));
  53
  54 #define BIOS_NUMDRIVES          0x475
  55 #define BIOSDISK_SECSIZE        512
  56 #define BUFSIZE                 (1 * BIOSDISK_SECSIZE)
  57
  58 #define DT_ATAPI                0x10            /* disk type for ATAPI floppies */
  59 #define WDMAJOR                 0               /* major numbers for devices we frontend for */
  60 #define WFDMAJOR                1
  61 #define FDMAJOR                 2
  62 #define DAMAJOR                 4
  63
  64 #ifdef DISK_DEBUG
  65 # define DEBUG(fmt, args...)    printf("%s: " fmt "\n" , __func__ , ## args)
  66 #else
  67 # define DEBUG(fmt, args...)
  68 #endif
  69
  70 /*
  71  * List of BIOS devices, translation from disk unit number to
  72  * BIOS unit number.
  73  */
  74 static struct bdinfo
  75 {
  76         int             bd_unit;        /* BIOS unit number */
  77         int             bd_cyl;         /* BIOS geometry */
  78         int             bd_hds;
  79         int             bd_sec;
  80         int             bd_flags;
  81 #define BD_MODEINT13    0x0000
  82 #define BD_MODEEDD1     0x0001
  83 #define BD_MODEEDD3     0x0002
  84 #define BD_MODEMASK     0x0003
  85 #define BD_FLOPPY       0x0004
  86         int             bd_type;        /* BIOS 'drive type' (floppy only) */
  87         uint16_t        bd_sectorsize;  /* Sector size */
  88         uint64_t        bd_sectors;     /* Disk size */
  89         int             bd_open;        /* reference counter */
  90         void            *bd_bcache;     /* buffer cache data */
  91 } bdinfo [MAXBDDEV];
  92 static int nbdinfo = 0;
  93
  94 #define BD(dev)         (bdinfo[(dev)->d_unit])
  95
  96 static int bd_read(struct disk_devdesc *dev, daddr_t dblk, int blks,
  97     caddr_t dest);
  98 static int bd_write(struct disk_devdesc *dev, daddr_t dblk, int blks,
  99     caddr_t dest);
 100 static int bd_int13probe(struct bdinfo *bd);
 101
 102 static int bd_init(void);
 103 static int bd_strategy(void *devdata, int flag, daddr_t dblk, size_t size,
 104     char *buf, size_t *rsize);
 105 static int bd_realstrategy(void *devdata, int flag, daddr_t dblk, size_t size,
 106     char *buf, size_t *rsize);
 107 static int bd_open(struct open_file *f, ...);
 108 static int bd_close(struct open_file *f);
 109 static int bd_ioctl(struct open_file *f, u_long cmd, void *data);
 110 static int bd_print(int verbose);
 111
 112 struct devsw biosdisk = {
 113         "disk",
 114         DEVT_DISK,
 115         bd_init,
 116         bd_strategy,
 117         bd_open,
 118         bd_close,
 119         bd_ioctl,
 120         bd_print,
 121         NULL
 122 };
 123
 124 /*
 125  * Translate between BIOS device numbers and our private unit numbers.
 126  */
 127 int
 128 bd_bios2unit(int biosdev)
 129 {
 130         int i;
 131
 132         DEBUG("looking for bios device 0x%x", biosdev);
 133         for (i = 0; i < nbdinfo; i++) {
 134                 DEBUG("bd unit %d is BIOS device 0x%x", i, bdinfo[i].bd_unit);
 135                 if (bdinfo[i].bd_unit == biosdev)
 136                         return (i);
 137         }
 138         return (-1);
 139 }
 140
 141 int
 142 bd_unit2bios(int unit)
 143 {
 144
 145         if ((unit >= 0) && (unit < nbdinfo))
 146                 return (bdinfo[unit].bd_unit);
 147         return (-1);
 148 }
 149
 150 /*
 151  * Quiz the BIOS for disk devices, save a little info about them.
 152  */
 153 static int
 154 bd_init(void)
 155 {
 156         int base, unit, nfd = 0;
 157
 158         /* sequence 0, 0x80 */
 159         for (base = 0; base <= 0x80; base += 0x80) {
 160                 for (unit = base; (nbdinfo < MAXBDDEV); unit++) {
 161 #ifndef VIRTUALBOX
 162                         /*
 163                          * Check the BIOS equipment list for number
 164                          * of fixed disks.
 165                          */
 166                         if(base == 0x80 &&
 167                             (nfd >= *(unsigned char *)PTOV(BIOS_NUMDRIVES)))
 168                                 break;
 169 #endif
 170                         bdinfo[nbdinfo].bd_open = 0;
 171                         bdinfo[nbdinfo].bd_bcache = NULL;
 172                         bdinfo[nbdinfo].bd_unit = unit;
 173                         bdinfo[nbdinfo].bd_flags = unit < 0x80 ? BD_FLOPPY: 0;
 174                         if (!bd_int13probe(&bdinfo[nbdinfo]))
 175                                 break;
 176
 177 #ifndef BOOT2
 178                         /* XXX we need "disk aliases" to make this simpler */
 179                         printf("BIOS drive %c: is disk%d\n", (unit < 0x80) ?
 180                             ('A' + unit): ('C' + unit - 0x80), nbdinfo);
 181 #endif
 182                         nbdinfo++;
 183                         if (base == 0x80)
 184                                 nfd++;
 185                 }
 186         }
 187         bcache_add_dev(nbdinfo);
 188         return(0);
 189 }
 190
 191 /*
 192  * Try to detect a device supported by the legacy int13 BIOS
 193  */
 194 static int
 195 bd_int13probe(struct bdinfo *bd)
 196 {
 197         struct edd_params params;
 198         int ret = 1;    /* assume success */
 199
 200         v86.ctl = V86_FLAGS;
 201         v86.addr = 0x13;
 202         v86.eax = 0x800;
 203         v86.edx = bd->bd_unit;
 204         v86int();
 205
 206         /* Don't error out if we get bad sector number, try EDD as well */
 207         if (V86_CY(v86.efl) ||  /* carry set */
 208             (v86.edx & 0xff) <= (unsigned)(bd->bd_unit & 0x7f)) /* unit # bad */
 209                 return (0);     /* skip device */
 210
 211         if ((v86.ecx & 0x3f) == 0)      /* absurd sector number */
 212                 ret = 0;        /* set error */
 213
 214         /* Convert max cyl # -> # of cylinders */
 215         bd->bd_cyl = ((v86.ecx & 0xc0) << 2) + ((v86.ecx & 0xff00) >> 8) + 1;
 216         /* Convert max head # -> # of heads */
 217         bd->bd_hds = ((v86.edx & 0xff00) >> 8) + 1;
 218         bd->bd_sec = v86.ecx & 0x3f;
 219         bd->bd_type = v86.ebx & 0xff;
 220         bd->bd_flags |= BD_MODEINT13;
 221
 222         /* Calculate sectors count from the geometry */
 223         bd->bd_sectors = bd->bd_cyl * bd->bd_hds * bd->bd_sec;
 224         bd->bd_sectorsize = BIOSDISK_SECSIZE;
 225         DEBUG("unit 0x%x geometry %d/%d/%d", bd->bd_unit, bd->bd_cyl,
 226             bd->bd_hds, bd->bd_sec);
 227
 228         /* Determine if we can use EDD with this device. */
 229         v86.ctl = V86_FLAGS;
 230         v86.addr = 0x13;
 231         v86.eax = 0x4100;
 232         v86.edx = bd->bd_unit;
 233         v86.ebx = 0x55aa;
 234         v86int();
 235         if (V86_CY(v86.efl) ||  /* carry set */
 236             (v86.ebx & 0xffff) != 0xaa55 || /* signature */
 237             (v86.ecx & EDD_INTERFACE_FIXED_DISK) == 0)
 238                 return (ret);   /* return code from int13 AH=08 */
 239
 240         /* EDD supported */
 241         bd->bd_flags |= BD_MODEEDD1;
 242         if ((v86.eax & 0xff00) >= 0x3000)
 243                 bd->bd_flags |= BD_MODEEDD3;
 244         /* Get disk params */
 245         params.len = sizeof(struct edd_params);
 246         v86.ctl = V86_FLAGS;
 247         v86.addr = 0x13;
 248         v86.eax = 0x4800;
 249         v86.edx = bd->bd_unit;
 250         v86.ds = VTOPSEG(&params);
 251         v86.esi = VTOPOFF(&params);
 252         v86int();
 253         if (!V86_CY(v86.efl)) {
 254                 uint64_t total;
 255
 256                 /*
 257                  * Sector size must be a multiple of 512 bytes.
 258                  * An alternate test would be to check power of 2,
 259                  * powerof2(params.sector_size).
 260                  */
 261                 if (params.sector_size % BIOSDISK_SECSIZE)
 262                         bd->bd_sectorsize = BIOSDISK_SECSIZE;
 263                 else
 264                         bd->bd_sectorsize = params.sector_size;
 265
 266                 total = bd->bd_sectorsize * params.sectors;
 267                 if (params.sectors != 0) {
 268                         /* Only update if we did not overflow. */
 269                         if (total > params.sectors)
 270                                 bd->bd_sectors = params.sectors;
 271                 }
 272
 273                 total = (uint64_t)params.cylinders *
 274                     params.heads * params.sectors_per_track;
 275                 if (bd->bd_sectors < total)
 276                         bd->bd_sectors = total;
 277
 278                 ret = 1;
 279         }
 280         DEBUG("unit 0x%x flags %x, sectors %llu, sectorsize %u",
 281             bd->bd_unit, bd->bd_flags, bd->bd_sectors, bd->bd_sectorsize);
 282         return (ret);
 283 }
 284
 285 /*
 286  * Print information about disks
 287  */
 288 static int
 289 bd_print(int verbose)
 290 {
 291         static char line[80];
 292         struct disk_devdesc dev;
 293         int i, ret = 0;
 294
 295         if (nbdinfo == 0)
 296                 return (0);
 297
 298         printf("%s devices:", biosdisk.dv_name);
 299         if ((ret = pager_output("\n")) != 0)
 300                 return (ret);
 301
 302         for (i = 0; i < nbdinfo; i++) {
 303                 snprintf(line, sizeof (line),
 304                     "    disk%d:   BIOS drive %c (%ju X %u):\n", i,
 305                     (bdinfo[i].bd_unit < 0x80) ? ('A' + bdinfo[i].bd_unit):
 306                     ('C' + bdinfo[i].bd_unit - 0x80),
 307                     (uintmax_t)bdinfo[i].bd_sectors,
 308                     bdinfo[i].bd_sectorsize);
 309                 ret = pager_output(line);
 310                 if (ret != 0)
 311                         return (ret);
 312
 313                 dev.d_dev = &biosdisk;
 314                 dev.d_unit = i;
 315                 dev.d_slice = -1;
 316                 dev.d_partition = -1;
 317                 if (disk_open(&dev,
 318                     bdinfo[i].bd_sectorsize * bdinfo[i].bd_sectors,
 319                     bdinfo[i].bd_sectorsize) == 0) {
 320                         sprintf(line, "    disk%d", i);
 321                         ret = disk_print(&dev, line, verbose);
 322                         disk_close(&dev);
 323                         if (ret != 0)
 324                                 return (ret);
 325                 }
 326         }
 327         return (ret);
 328 }
 329
 330 /*
 331  * Attempt to open the disk described by (dev) for use by (f).
 332  *
 333  * Note that the philosophy here is "give them exactly what
 334  * they ask for".  This is necessary because being too "smart"
 335  * about what the user might want leads to complications.
 336  * (eg. given no slice or partition value, with a disk that is
 337  *  sliced - are they after the first BSD slice, or the DOS
 338  *  slice before it?)
 339  */
 340 static int
 341 bd_open(struct open_file *f, ...)
 342 {
 343         struct disk_devdesc *dev;
 344         struct disk_devdesc disk;
 345         va_list ap;
 346         uint64_t size;
 347         int rc;
 348
 349         va_start(ap, f);
 350         dev = va_arg(ap, struct disk_devdesc *);
 351         va_end(ap);
 352
 353         if (dev->d_unit < 0 || dev->d_unit >= nbdinfo)
 354                 return (EIO);
 355         BD(dev).bd_open++;
 356         if (BD(dev).bd_bcache == NULL)
 357             BD(dev).bd_bcache = bcache_allocate();
 358
 359         /*
 360          * Read disk size from partition.
 361          * This is needed to work around buggy BIOS systems returning
 362          * wrong (truncated) disk media size.
 363          * During bd_probe() we tested if the mulitplication of bd_sectors
 364          * would overflow so it should be safe to perform here.
 365          */
 366         disk.d_dev = dev->d_dev;
 367         disk.d_type = dev->d_type;
 368         disk.d_unit = dev->d_unit;
 369         disk.d_opendata = NULL;
 370         disk.d_slice = -1;
 371         disk.d_partition = -1;
 372         disk.d_offset = 0;
 373
 374         if (disk_open(&disk, BD(dev).bd_sectors * BD(dev).bd_sectorsize,
 375             BD(dev).bd_sectorsize) == 0) {
 376
 377                 if (disk_ioctl(&disk, DIOCGMEDIASIZE, &size) == 0) {
 378                         size /= BD(dev).bd_sectorsize;
 379                         if (size > BD(dev).bd_sectors)
 380                                 BD(dev).bd_sectors = size;
 381                 }
 382                 disk_close(&disk);
 383         }
 384
 385         rc = disk_open(dev, BD(dev).bd_sectors * BD(dev).bd_sectorsize,
 386             BD(dev).bd_sectorsize);
 387         if (rc != 0) {
 388                 BD(dev).bd_open--;
 389                 if (BD(dev).bd_open == 0) {
 390                         bcache_free(BD(dev).bd_bcache);
 391                         BD(dev).bd_bcache = NULL;
 392                 }
 393         }
 394         return (rc);
 395 }
 396
 397 static int
 398 bd_close(struct open_file *f)
 399 {
 400         struct disk_devdesc *dev;
 401
 402         dev = (struct disk_devdesc *)f->f_devdata;
 403         BD(dev).bd_open--;
 404         if (BD(dev).bd_open == 0) {
 405             bcache_free(BD(dev).bd_bcache);
 406             BD(dev).bd_bcache = NULL;
 407         }
 408         return (disk_close(dev));
 409 }
 410
 411 static int
 412 bd_ioctl(struct open_file *f, u_long cmd, void *data)
 413 {
 414         struct disk_devdesc *dev;
 415         int rc;
 416
 417         dev = (struct disk_devdesc *)f->f_devdata;
 418
 419         rc = disk_ioctl(dev, cmd, data);
 420         if (rc != ENOTTY)
 421                 return (rc);
 422
 423         switch (cmd) {
 424         case DIOCGSECTORSIZE:
 425                 *(u_int *)data = BD(dev).bd_sectorsize;
 426                 break;
 427         case DIOCGMEDIASIZE:
 428                 *(uint64_t *)data = BD(dev).bd_sectors * BD(dev).bd_sectorsize;
 429                 break;
 430         default:
 431                 return (ENOTTY);
 432         }
 433         return (0);
 434 }
 435
 436 static int
 437 bd_strategy(void *devdata, int rw, daddr_t dblk, size_t size,
 438     char *buf, size_t *rsize)
 439 {
 440         struct bcache_devdata bcd;
 441         struct disk_devdesc *dev;
 442
 443         dev = (struct disk_devdesc *)devdata;
 444         bcd.dv_strategy = bd_realstrategy;
 445         bcd.dv_devdata = devdata;
 446         bcd.dv_cache = BD(dev).bd_bcache;
 447
 448         return (bcache_strategy(&bcd, rw, dblk + dev->d_offset, size,
 449             buf, rsize));
 450 }
 451
 452 static int
 453 bd_realstrategy(void *devdata, int rw, daddr_t dblk, size_t size,
 454     char *buf, size_t *rsize)
 455 {
 456     struct disk_devdesc *dev = (struct disk_devdesc *)devdata;
 457     uint64_t            disk_blocks;
 458     int                 blks, rc;
 459 #ifdef BD_SUPPORT_FRAGS /* XXX: sector size */
 460     char                fragbuf[BIOSDISK_SECSIZE];
 461     size_t              fragsize;
 462
 463     fragsize = size % BIOSDISK_SECSIZE;
 464 #else
 465     if (size % BD(dev).bd_sectorsize)
 466         panic("bd_strategy: %d bytes I/O not multiple of block size", size);
 467 #endif
 468
 469     DEBUG("open_disk %p", dev);
 470
 471     /*
 472      * Check the value of the size argument. We do have quite small
 473      * heap (64MB), but we do not know good upper limit, so we check against
 474      * INT_MAX here. This will also protect us against possible overflows
 475      * while translating block count to bytes.
 476      */
 477     if (size > INT_MAX) {
 478         DEBUG("too large read: %zu bytes", size);
 479         return (EIO);
 480     }
 481
 482     blks = size / BD(dev).bd_sectorsize;
 483     if (dblk > dblk + blks)
 484         return (EIO);
 485
 486     if (rsize)
 487         *rsize = 0;
 488
 489     /* Get disk blocks, this value is either for whole disk or for partition */
 490     if (disk_ioctl(dev, DIOCGMEDIASIZE, &disk_blocks) == 0) {
 491         /* DIOCGMEDIASIZE does return bytes. */
 492         disk_blocks /= BD(dev).bd_sectorsize;
 493     } else {
 494         /* We should not get here. Just try to survive. */
 495         disk_blocks = BD(dev).bd_sectors - dev->d_offset;
 496     }
 497
 498     /* Validate source block address. */
 499     if (dblk < dev->d_offset || dblk >= dev->d_offset + disk_blocks)
 500         return (EIO);
 501
 502     /*
 503      * Truncate if we are crossing disk or partition end.
 504      */
 505     if (dblk + blks >= dev->d_offset + disk_blocks) {
 506         blks = dev->d_offset + disk_blocks - dblk;
 507         size = blks * BD(dev).bd_sectorsize;
 508         DEBUG("short read %d", blks);
 509     }
 510
 511     switch (rw & F_MASK) {
 512     case F_READ:
 513         DEBUG("read %d from %lld to %p", blks, dblk, buf);
 514
 515         if (blks && (rc = bd_read(dev, dblk, blks, buf))) {
 516             /* Filter out floppy controller errors */
 517             if (BD(dev).bd_flags != BD_FLOPPY || rc != 0x20) {
 518                 printf("read %d from %lld to %p, error: 0x%x\n", blks, dblk,
 519                     buf, rc);
 520             }
 521             return (EIO);
 522         }
 523 #ifdef BD_SUPPORT_FRAGS /* XXX: sector size */
 524         DEBUG("bd_strategy: frag read %d from %d+%d to %p",
 525             fragsize, dblk, blks, buf + (blks * BIOSDISK_SECSIZE));
 526         if (fragsize && bd_read(od, dblk + blks, 1, fragsize)) {
 527             DEBUG("frag read error");
 528             return(EIO);
 529         }
 530         bcopy(fragbuf, buf + (blks * BIOSDISK_SECSIZE), fragsize);
 531 #endif
 532         break;
 533     case F_WRITE :
 534         DEBUG("write %d from %d to %p", blks, dblk, buf);
 535
 536         if (blks && bd_write(dev, dblk, blks, buf)) {
 537             DEBUG("write error");
 538             return (EIO);
 539         }
 540 #ifdef BD_SUPPORT_FRAGS
 541         if(fragsize) {
 542             DEBUG("Attempted to write a frag");
 543             return (EIO);
 544         }
 545 #endif
 546         break;
 547     default:
 548         /* DO NOTHING */
 549         return (EROFS);
 550     }
 551
 552     if (rsize)
 553         *rsize = size;
 554     return (0);
 555 }
 556
 557 static int
 558 bd_edd_io(struct disk_devdesc *dev, daddr_t dblk, int blks, caddr_t dest,
 559     int dowrite)
 560 {
 561     static struct edd_packet packet;
 562
 563     packet.len = sizeof(struct edd_packet);
 564     packet.count = blks;
 565     packet.off = VTOPOFF(dest);
 566     packet.seg = VTOPSEG(dest);
 567     packet.lba = dblk;
 568     v86.ctl = V86_FLAGS;
 569     v86.addr = 0x13;
 570     if (dowrite)
 571         /* Should we Write with verify ?? 0x4302 ? */
 572         v86.eax = 0x4300;
 573     else
 574         v86.eax = 0x4200;
 575     v86.edx = BD(dev).bd_unit;
 576     v86.ds = VTOPSEG(&packet);
 577     v86.esi = VTOPOFF(&packet);
 578     v86int();
 579     if (V86_CY(v86.efl))
 580         return (v86.eax >> 8);
 581     return (0);
 582 }
 583
 584 static int
 585 bd_chs_io(struct disk_devdesc *dev, daddr_t dblk, int blks, caddr_t dest,
 586     int dowrite)
 587 {
 588     u_int       x, bpc, cyl, hd, sec;
 589
 590     bpc = BD(dev).bd_sec * BD(dev).bd_hds;      /* blocks per cylinder */
 591     x = dblk;
 592     cyl = x / bpc;                      /* block # / blocks per cylinder */
 593     x %= bpc;                           /* block offset into cylinder */
 594     hd = x / BD(dev).bd_sec;            /* offset / blocks per track */
 595     sec = x % BD(dev).bd_sec;           /* offset into track */
 596
 597     /* correct sector number for 1-based BIOS numbering */
 598     sec++;
 599
 600     if (cyl > 1023)
 601         /* CHS doesn't support cylinders > 1023. */
 602         return (1);
 603
 604     v86.ctl = V86_FLAGS;
 605     v86.addr = 0x13;
 606     if (dowrite)
 607         v86.eax = 0x300 | blks;
 608     else
 609         v86.eax = 0x200 | blks;
 610     v86.ecx = ((cyl & 0xff) << 8) | ((cyl & 0x300) >> 2) | sec;
 611     v86.edx = (hd << 8) | BD(dev).bd_unit;
 612     v86.es = VTOPSEG(dest);
 613     v86.ebx = VTOPOFF(dest);
 614     v86int();
 615     if (V86_CY(v86.efl))
 616         return (v86.eax >> 8);
 617     return (0);
 618 }
 619
 620 static int
 621 bd_io(struct disk_devdesc *dev, daddr_t dblk, int blks, caddr_t dest,
 622     int dowrite)
 623 {
 624     u_int       x, sec, result, resid, retry, maxfer;
 625     caddr_t     p, xp, bbuf;
 626
 627     /* Just in case some idiot actually tries to read/write -1 blocks... */
 628     if (blks < 0)
 629         return (-1);
 630
 631     resid = blks;
 632     p = dest;
 633
 634     /* Decide whether we have to bounce */
 635     if (VTOP(dest) >> 20 != 0 || (BD(dev).bd_unit < 0x80 &&
 636         (VTOP(dest) >> 16) != (VTOP(dest +
 637         blks * BD(dev).bd_sectorsize) >> 16))) {
 638
 639         /*
 640          * There is a 64k physical boundary somewhere in the
 641          * destination buffer, or the destination buffer is above
 642          * first 1MB of physical memory so we have to arrange a
 643          * suitable bounce buffer.  Allocate a buffer twice as large
 644          * as we need to.  Use the bottom half unless there is a break
 645          * there, in which case we use the top half.
 646          */
 647         x = V86_IO_BUFFER_SIZE / BD(dev).bd_sectorsize;
 648         if (x == 0)
 649                 panic("BUG: Real mode buffer is too small\n");
 650         x = min(x, (unsigned)blks);
 651         bbuf = PTOV(V86_IO_BUFFER);
 652         maxfer = x;             /* limit transfers to bounce region size */
 653     } else {
 654         bbuf = NULL;
 655         maxfer = 0;
 656     }
 657
 658     while (resid > 0) {
 659         /*
 660          * Play it safe and don't cross track boundaries.
 661          * (XXX this is probably unnecessary)
 662          */
 663         sec = dblk % BD(dev).bd_sec;    /* offset into track */
 664         x = min(BD(dev).bd_sec - sec, resid);
 665         if (maxfer > 0)
 666             x = min(x, maxfer);         /* fit bounce buffer */
 667
 668         /* where do we transfer to? */
 669         xp = bbuf == NULL ? p : bbuf;
 670
 671         /*
 672          * Put your Data In, Put your Data out,
 673          * Put your Data In, and shake it all about
 674          */
 675         if (dowrite && bbuf != NULL)
 676             bcopy(p, bbuf, x * BD(dev).bd_sectorsize);
 677
 678         /*
 679          * Loop retrying the operation a couple of times.  The BIOS
 680          * may also retry.
 681          */
 682         for (retry = 0; retry < 3; retry++) {
 683             /* if retrying, reset the drive */
 684             if (retry > 0) {
 685                 v86.ctl = V86_FLAGS;
 686                 v86.addr = 0x13;
 687                 v86.eax = 0;
 688                 v86.edx = BD(dev).bd_unit;
 689                 v86int();
 690             }
 691
 692             if (BD(dev).bd_flags & BD_MODEEDD1)
 693                 result = bd_edd_io(dev, dblk, x, xp, dowrite);
 694             else
 695                 result = bd_chs_io(dev, dblk, x, xp, dowrite);
 696             if (result == 0)
 697                 break;
 698         }
 699
 700         if (dowrite)
 701             DEBUG("Write %d sector(s) from %p (0x%x) to %lld %s", x,
 702                 p, VTOP(p), dblk, result ? "failed" : "ok");
 703         else
 704             DEBUG("Read %d sector(s) from %lld to %p (0x%x) %s", x,
 705                 dblk, p, VTOP(p), result ? "failed" : "ok");
 706         if (result) {
 707             return(result);
 708         }
 709         if (!dowrite && bbuf != NULL)
 710             bcopy(bbuf, p, x * BD(dev).bd_sectorsize);
 711         p += (x * BD(dev).bd_sectorsize);
 712         dblk += x;
 713         resid -= x;
 714     }
 715
 716 /*    hexdump(dest, (blks * BD(dev).bd_sectorsize)); */
 717     return(0);
 718 }
 719
 720 static int
 721 bd_read(struct disk_devdesc *dev, daddr_t dblk, int blks, caddr_t dest)
 722 {
 723
 724         return (bd_io(dev, dblk, blks, dest, 0));
 725 }
 726
 727 static int
 728 bd_write(struct disk_devdesc *dev, daddr_t dblk, int blks, caddr_t dest)
 729 {
 730
 731         return (bd_io(dev, dblk, blks, dest, 1));
 732 }
 733
 734 /*
 735  * Return the BIOS geometry of a given "fixed drive" in a format
 736  * suitable for the legacy bootinfo structure.  Since the kernel is
 737  * expecting raw int 0x13/0x8 values for N_BIOS_GEOM drives, we
 738  * prefer to get the information directly, rather than rely on being
 739  * able to put it together from information already maintained for
 740  * different purposes and for a probably different number of drives.
 741  *
 742  * For valid drives, the geometry is expected in the format (31..0)
 743  * "000000cc cccccccc hhhhhhhh 00ssssss"; and invalid drives are
 744  * indicated by returning the geometry of a "1.2M" PC-format floppy
 745  * disk.  And, incidentally, what is returned is not the geometry as
 746  * such but the highest valid cylinder, head, and sector numbers.
 747  */
 748 u_int32_t
 749 bd_getbigeom(int bunit)
 750 {
 751
 752     v86.ctl = V86_FLAGS;
 753     v86.addr = 0x13;
 754     v86.eax = 0x800;
 755     v86.edx = 0x80 + bunit;
 756     v86int();
 757     if (V86_CY(v86.efl))
 758         return 0x4f010f;
 759     return ((v86.ecx & 0xc0) << 18) | ((v86.ecx & 0xff00) << 8) |
 760            (v86.edx & 0xff00) | (v86.ecx & 0x3f);
 761 }
 762
 763 /*
 764  * Return a suitable dev_t value for (dev).
 765  *
 766  * In the case where it looks like (dev) is a SCSI disk, we allow the number of
 767  * IDE disks to be specified in $num_ide_disks.  There should be a Better Way.
 768  */
 769 int
 770 bd_getdev(struct i386_devdesc *d)
 771 {
 772     struct disk_devdesc         *dev;
 773     int                         biosdev;
 774     int                         major;
 775     int                         rootdev;
 776     char                        *nip, *cp;
 777     int                         i, unit;
 778
 779     dev = (struct disk_devdesc *)d;
 780     biosdev = bd_unit2bios(dev->d_unit);
 781     DEBUG("unit %d BIOS device %d", dev->d_unit, biosdev);
 782     if (biosdev == -1)                          /* not a BIOS device */
 783         return(-1);
 784     if (disk_open(dev, BD(dev).bd_sectors * BD(dev).bd_sectorsize,
 785         BD(dev).bd_sectorsize) != 0)            /* oops, not a viable device */
 786             return (-1);
 787     else
 788         disk_close(dev);
 789
 790     if (biosdev < 0x80) {
 791         /* floppy (or emulated floppy) or ATAPI device */
 792         if (bdinfo[dev->d_unit].bd_type == DT_ATAPI) {
 793             /* is an ATAPI disk */
 794             major = WFDMAJOR;
 795         } else {
 796             /* is a floppy disk */
 797             major = FDMAJOR;
 798         }
 799     } else {
 800             /* assume an IDE disk */
 801             major = WDMAJOR;
 802     }
 803     /* default root disk unit number */
 804     unit = biosdev & 0x7f;
 805
 806     /* XXX a better kludge to set the root disk unit number */
 807     if ((nip = getenv("root_disk_unit")) != NULL) {
 808         i = strtol(nip, &cp, 0);
 809         /* check for parse error */
 810         if ((cp != nip) && (*cp == 0))
 811             unit = i;
 812     }
 813
 814     rootdev = MAKEBOOTDEV(major, dev->d_slice + 1, unit, dev->d_partition);
 815     DEBUG("dev is 0x%x\n", rootdev);
 816     return(rootdev);
 817 }