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 __FBSDID("$FreeBSD: stable/12/stand/i386/libi386/biosdisk.c 372563 2022-09-18 06:29:03Z kevans $");
30
31 /*
32 * BIOS disk device handling.
33 *
34 * Ideas and algorithms from:
35 *
36 * - NetBSD libi386/biosdisk.c
37 * - FreeBSD biosboot/disk.c
38 *
39 */
40
41 #include <sys/disk.h>
42 #include <sys/limits.h>
43 #include <sys/queue.h>
44 #include <stand.h>
45 #include <machine/bootinfo.h>
46 #include <stdarg.h>
47 #include <stdbool.h>
48
49 #include <bootstrap.h>
50 #include <btxv86.h>
51 #include <edd.h>
52 #include "disk.h"
53 #include "libi386.h"
54
55 #define BIOS_NUMDRIVES 0x475
56 #define BIOSDISK_SECSIZE 512
57 #define BUFSIZE (1 * BIOSDISK_SECSIZE)
58
59 #define DT_ATAPI 0x10 /* disk type for ATAPI floppies */
60 #define WDMAJOR 0 /* major numbers for devices we frontend for */
61 #define WFDMAJOR 1
62 #define FDMAJOR 2
63 #define DAMAJOR 4
64 #define ACDMAJOR 117
65 #define CDMAJOR 15
66
67 /*
68 * INT13 commands
69 */
70 #define CMD_RESET 0x0000
71 #define CMD_READ_CHS 0x0200
72 #define CMD_WRITE_CHS 0x0300
73 #define CMD_READ_PARAM 0x0800
74 #define CMD_DRIVE_TYPE 0x1500
75 #define CMD_CHECK_EDD 0x4100
76 #define CMD_READ_LBA 0x4200
77 #define CMD_WRITE_LBA 0x4300
78 #define CMD_EXT_PARAM 0x4800
79 #define CMD_CD_GET_STATUS 0x4b01
80
81 #define DISK_BIOS 0x13
82
83 #ifdef DISK_DEBUG
84 #define DPRINTF(fmt, args...) printf("%s: " fmt "\n", __func__, ## args)
85 #else
86 #define DPRINTF(fmt, args...) ((void)0)
87 #endif
88
89 struct specification_packet {
90 uint8_t sp_size;
91 uint8_t sp_bootmedia;
92 uint8_t sp_drive;
93 uint8_t sp_controller;
94 uint32_t sp_lba;
95 uint16_t sp_devicespec;
96 uint16_t sp_buffersegment;
97 uint16_t sp_loadsegment;
98 uint16_t sp_sectorcount;
99 uint16_t sp_cylsec;
100 uint8_t sp_head;
101 uint8_t sp_dummy[16]; /* Avoid memory corruption */
102 };
103
104 /*
105 * List of BIOS devices, translation from disk unit number to
106 * BIOS unit number.
107 */
108 typedef struct bdinfo
109 {
110 STAILQ_ENTRY(bdinfo) bd_link; /* link in device list */
111 int bd_unit; /* BIOS unit number */
112 int bd_cyl; /* BIOS geometry */
113 int bd_hds;
114 int bd_sec;
115 int bd_flags;
116 #define BD_MODEINT13 0x0000
117 #define BD_MODEEDD1 0x0001
118 #define BD_MODEEDD3 0x0002
119 #define BD_MODEEDD (BD_MODEEDD1 | BD_MODEEDD3)
120 #define BD_MODEMASK 0x0003
121 #define BD_FLOPPY 0x0004
122 #define BD_CDROM 0x0008
123 #define BD_NO_MEDIA 0x0010
124 int bd_type; /* BIOS 'drive type' (floppy only) */
125 uint16_t bd_sectorsize; /* Sector size */
126 uint64_t bd_sectors; /* Disk size */
127 int bd_open; /* reference counter */
128 void *bd_bcache; /* buffer cache data */
129 } bdinfo_t;
130
131 #define BD_RD 0
132 #define BD_WR 1
133
134 typedef STAILQ_HEAD(bdinfo_list, bdinfo) bdinfo_list_t;
135 static bdinfo_list_t fdinfo = STAILQ_HEAD_INITIALIZER(fdinfo);
136 static bdinfo_list_t cdinfo = STAILQ_HEAD_INITIALIZER(cdinfo);
137 static bdinfo_list_t hdinfo = STAILQ_HEAD_INITIALIZER(hdinfo);
138
139 static void bd_io_workaround(bdinfo_t *);
140 static int bd_io(struct disk_devdesc *, bdinfo_t *, daddr_t, int, caddr_t, int);
141 static bool bd_int13probe(bdinfo_t *);
142
143 static int bd_init(void);
144 static int cd_init(void);
145 static int fd_init(void);
146 static int bd_strategy(void *devdata, int flag, daddr_t dblk, size_t size,
147 char *buf, size_t *rsize);
148 static int bd_realstrategy(void *devdata, int flag, daddr_t dblk, size_t size,
149 char *buf, size_t *rsize);
150 static int bd_open(struct open_file *f, ...);
151 static int bd_close(struct open_file *f);
152 static int bd_ioctl(struct open_file *f, u_long cmd, void *data);
153 static int bd_print(int verbose);
154 static int cd_print(int verbose);
155 static int fd_print(int verbose);
156 static void bd_reset_disk(int);
157 static int bd_get_diskinfo_std(struct bdinfo *);
158
159 struct devsw biosfd = {
160 .dv_name = "fd",
161 .dv_type = DEVT_FD,
162 .dv_init = fd_init,
163 .dv_strategy = bd_strategy,
164 .dv_open = bd_open,
165 .dv_close = bd_close,
166 .dv_ioctl = bd_ioctl,
167 .dv_print = fd_print,
168 .dv_cleanup = NULL
169 };
170
171 struct devsw bioscd = {
172 .dv_name = "cd",
173 .dv_type = DEVT_CD,
174 .dv_init = cd_init,
175 .dv_strategy = bd_strategy,
176 .dv_open = bd_open,
177 .dv_close = bd_close,
178 .dv_ioctl = bd_ioctl,
179 .dv_print = cd_print,
180 .dv_cleanup = NULL
181 };
182
183 struct devsw bioshd = {
184 .dv_name = "disk",
185 .dv_type = DEVT_DISK,
186 .dv_init = bd_init,
187 .dv_strategy = bd_strategy,
188 .dv_open = bd_open,
189 .dv_close = bd_close,
190 .dv_ioctl = bd_ioctl,
191 .dv_print = bd_print,
192 .dv_cleanup = NULL
193 };
194
195 static bdinfo_list_t *
bd_get_bdinfo_list(struct devsw * dev)196 bd_get_bdinfo_list(struct devsw *dev)
197 {
198 if (dev->dv_type == DEVT_DISK)
199 return (&hdinfo);
200 if (dev->dv_type == DEVT_CD)
201 return (&cdinfo);
202 if (dev->dv_type == DEVT_FD)
203 return (&fdinfo);
204 return (NULL);
205 }
206
207 /* XXX this gets called way way too often, investigate */
208 static bdinfo_t *
bd_get_bdinfo(struct devdesc * dev)209 bd_get_bdinfo(struct devdesc *dev)
210 {
211 bdinfo_list_t *bdi;
212 bdinfo_t *bd = NULL;
213 int unit;
214
215 bdi = bd_get_bdinfo_list(dev->d_dev);
216 if (bdi == NULL)
217 return (bd);
218
219 unit = 0;
220 STAILQ_FOREACH(bd, bdi, bd_link) {
221 if (unit == dev->d_unit)
222 return (bd);
223 unit++;
224 }
225 return (bd);
226 }
227
228 /*
229 * Translate between BIOS device numbers and our private unit numbers.
230 */
231 int
bd_bios2unit(int biosdev)232 bd_bios2unit(int biosdev)
233 {
234 bdinfo_list_t *bdi[] = { &fdinfo, &cdinfo, &hdinfo, NULL };
235 bdinfo_t *bd;
236 int i, unit;
237
238 DPRINTF("looking for bios device 0x%x", biosdev);
239 for (i = 0; bdi[i] != NULL; i++) {
240 unit = 0;
241 STAILQ_FOREACH(bd, bdi[i], bd_link) {
242 if (bd->bd_unit == biosdev) {
243 DPRINTF("bd unit %d is BIOS device 0x%x", unit,
244 bd->bd_unit);
245 return (unit);
246 }
247 unit++;
248 }
249 }
250 return (-1);
251 }
252
253 int
bd_unit2bios(struct i386_devdesc * dev)254 bd_unit2bios(struct i386_devdesc *dev)
255 {
256 bdinfo_list_t *bdi;
257 bdinfo_t *bd;
258 int unit;
259
260 bdi = bd_get_bdinfo_list(dev->dd.d_dev);
261 if (bdi == NULL)
262 return (-1);
263
264 unit = 0;
265 STAILQ_FOREACH(bd, bdi, bd_link) {
266 if (unit == dev->dd.d_unit)
267 return (bd->bd_unit);
268 unit++;
269 }
270 return (-1);
271 }
272
273 /*
274 * Use INT13 AH=15 - Read Drive Type.
275 */
276 static int
fd_count(void)277 fd_count(void)
278 {
279 int drive;
280
281 for (drive = 0; drive < MAXBDDEV; drive++) {
282 bd_reset_disk(drive);
283
284 v86.ctl = V86_FLAGS;
285 v86.addr = DISK_BIOS;
286 v86.eax = CMD_DRIVE_TYPE;
287 v86.edx = drive;
288 v86int();
289
290 if (V86_CY(v86.efl))
291 break;
292
293 if ((v86.eax & 0x300) == 0)
294 break;
295 }
296
297 return (drive);
298 }
299
300 /*
301 * Quiz the BIOS for disk devices, save a little info about them.
302 */
303 static int
fd_init(void)304 fd_init(void)
305 {
306 int unit, numfd;
307 bdinfo_t *bd;
308
309 numfd = fd_count();
310 for (unit = 0; unit < numfd; unit++) {
311 if ((bd = calloc(1, sizeof(*bd))) == NULL)
312 break;
313
314 bd->bd_sectorsize = BIOSDISK_SECSIZE;
315 bd->bd_flags = BD_FLOPPY;
316 bd->bd_unit = unit;
317
318 /* Use std diskinfo for floppy drive */
319 if (bd_get_diskinfo_std(bd) != 0) {
320 free(bd);
321 break;
322 }
323 if (bd->bd_sectors == 0)
324 bd->bd_flags |= BD_NO_MEDIA;
325
326 printf("BIOS drive %c: is %s%d\n", ('A' + unit),
327 biosfd.dv_name, unit);
328
329 STAILQ_INSERT_TAIL(&fdinfo, bd, bd_link);
330 }
331
332 bcache_add_dev(unit);
333 return (0);
334 }
335
336 static int
bd_init(void)337 bd_init(void)
338 {
339 int base, unit;
340 bdinfo_t *bd;
341
342 base = 0x80;
343 for (unit = 0; unit < *(unsigned char *)PTOV(BIOS_NUMDRIVES); unit++) {
344 /*
345 * Check the BIOS equipment list for number of fixed disks.
346 */
347 if ((bd = calloc(1, sizeof(*bd))) == NULL)
348 break;
349 bd->bd_unit = base + unit;
350 if (!bd_int13probe(bd)) {
351 free(bd);
352 break;
353 }
354
355 printf("BIOS drive %c: is %s%d\n", ('C' + unit),
356 bioshd.dv_name, unit);
357
358 STAILQ_INSERT_TAIL(&hdinfo, bd, bd_link);
359 }
360 bcache_add_dev(unit);
361 return (0);
362 }
363
364 /*
365 * We can't quiz, we have to be told what device to use, so this function
366 * doesn't do anything. Instead, the loader calls bc_add() with the BIOS
367 * device number to add.
368 */
369 static int
cd_init(void)370 cd_init(void)
371 {
372
373 return (0);
374 }
375
376 /*
377 * Information from bootable CD-ROM.
378 */
379 static int
bd_get_diskinfo_cd(struct bdinfo * bd)380 bd_get_diskinfo_cd(struct bdinfo *bd)
381 {
382 struct specification_packet bc_sp;
383 int ret = -1;
384
385 (void) memset(&bc_sp, 0, sizeof (bc_sp));
386 /* Set sp_size as per specification. */
387 bc_sp.sp_size = sizeof (bc_sp) - sizeof (bc_sp.sp_dummy);
388
389 v86.ctl = V86_FLAGS;
390 v86.addr = DISK_BIOS;
391 v86.eax = CMD_CD_GET_STATUS;
392 v86.edx = bd->bd_unit;
393 v86.ds = VTOPSEG(&bc_sp);
394 v86.esi = VTOPOFF(&bc_sp);
395 v86int();
396
397 if ((v86.eax & 0xff00) == 0 &&
398 bc_sp.sp_drive == bd->bd_unit) {
399 bd->bd_cyl = ((bc_sp.sp_cylsec & 0xc0) << 2) +
400 ((bc_sp.sp_cylsec & 0xff00) >> 8) + 1;
401 bd->bd_sec = bc_sp.sp_cylsec & 0x3f;
402 bd->bd_hds = bc_sp.sp_head + 1;
403 bd->bd_sectors = (uint64_t)bd->bd_cyl * bd->bd_hds * bd->bd_sec;
404
405 if (bc_sp.sp_bootmedia & 0x0F) {
406 /* Floppy or hard-disk emulation */
407 bd->bd_sectorsize = BIOSDISK_SECSIZE;
408 return (-1);
409 } else {
410 bd->bd_sectorsize = 2048;
411 bd->bd_flags = BD_MODEEDD | BD_CDROM;
412 ret = 0;
413 }
414 }
415
416 /*
417 * If this is the boot_drive, default to non-emulation bootable CD-ROM.
418 */
419 if (ret != 0 && bd->bd_unit >= 0x88) {
420 bd->bd_cyl = 0;
421 bd->bd_hds = 1;
422 bd->bd_sec = 15;
423 bd->bd_sectorsize = 2048;
424 bd->bd_flags = BD_MODEEDD | BD_CDROM;
425 bd->bd_sectors = 0;
426 ret = 0;
427 }
428
429 /*
430 * Note we can not use bd_get_diskinfo_ext() nor bd_get_diskinfo_std()
431 * here - some systems do get hung with those.
432 */
433 /*
434 * Still no size? use 7.961GB. The size does not really matter
435 * as long as it is reasonably large to make our reads to pass
436 * the sector count check.
437 */
438 if (bd->bd_sectors == 0)
439 bd->bd_sectors = 4173824;
440
441 return (ret);
442 }
443
444 int
bc_add(int biosdev)445 bc_add(int biosdev)
446 {
447 bdinfo_t *bd;
448 int nbcinfo = 0;
449
450 if (!STAILQ_EMPTY(&cdinfo))
451 return (-1);
452
453 if ((bd = calloc(1, sizeof(*bd))) == NULL)
454 return (-1);
455
456 bd->bd_unit = biosdev;
457 if (bd_get_diskinfo_cd(bd) < 0) {
458 free(bd);
459 return (-1);
460 }
461
462 STAILQ_INSERT_TAIL(&cdinfo, bd, bd_link);
463 printf("BIOS CD is cd%d\n", nbcinfo);
464 nbcinfo++;
465 bcache_add_dev(nbcinfo); /* register cd device in bcache */
466 return(0);
467 }
468
469 /*
470 * Return EDD version or 0 if EDD is not supported on this drive.
471 */
472 static int
bd_check_extensions(int unit)473 bd_check_extensions(int unit)
474 {
475 /* do not use ext calls for floppy devices */
476 if (unit < 0x80)
477 return (0);
478
479 /* Determine if we can use EDD with this device. */
480 v86.ctl = V86_FLAGS;
481 v86.addr = DISK_BIOS;
482 v86.eax = CMD_CHECK_EDD;
483 v86.edx = unit;
484 v86.ebx = EDD_QUERY_MAGIC;
485 v86int();
486
487 if (V86_CY(v86.efl) || /* carry set */
488 (v86.ebx & 0xffff) != EDD_INSTALLED) /* signature */
489 return (0);
490
491 /* extended disk access functions (AH=42h-44h,47h,48h) supported */
492 if ((v86.ecx & EDD_INTERFACE_FIXED_DISK) == 0)
493 return (0);
494
495 return ((v86.eax >> 8) & 0xff);
496 }
497
498 static void
bd_reset_disk(int unit)499 bd_reset_disk(int unit)
500 {
501 /* reset disk */
502 v86.ctl = V86_FLAGS;
503 v86.addr = DISK_BIOS;
504 v86.eax = CMD_RESET;
505 v86.edx = unit;
506 v86int();
507 }
508
509 /*
510 * Read CHS info. Return 0 on success, error otherwise.
511 */
512 static int
bd_get_diskinfo_std(struct bdinfo * bd)513 bd_get_diskinfo_std(struct bdinfo *bd)
514 {
515 bzero(&v86, sizeof(v86));
516 v86.ctl = V86_FLAGS;
517 v86.addr = DISK_BIOS;
518 v86.eax = CMD_READ_PARAM;
519 v86.edx = bd->bd_unit;
520 v86int();
521
522 if (V86_CY(v86.efl) && ((v86.eax & 0xff00) != 0))
523 return ((v86.eax & 0xff00) >> 8);
524
525 /* return custom error on absurd sector number */
526 if ((v86.ecx & 0x3f) == 0)
527 return (0x60);
528
529 bd->bd_cyl = ((v86.ecx & 0xc0) << 2) + ((v86.ecx & 0xff00) >> 8) + 1;
530 /* Convert max head # -> # of heads */
531 bd->bd_hds = ((v86.edx & 0xff00) >> 8) + 1;
532 bd->bd_sec = v86.ecx & 0x3f;
533 bd->bd_type = v86.ebx;
534 bd->bd_sectors = (uint64_t)bd->bd_cyl * bd->bd_hds * bd->bd_sec;
535
536 return (0);
537 }
538
539 /*
540 * Read EDD info. Return 0 on success, error otherwise.
541 *
542 * Avoid stack corruption on some systems by adding extra bytes to
543 * params block.
544 */
545 static int
bd_get_diskinfo_ext(struct bdinfo * bd)546 bd_get_diskinfo_ext(struct bdinfo *bd)
547 {
548 struct disk_params {
549 struct edd_params head;
550 struct edd_device_path_v3 device_path;
551 uint8_t dummy[16];
552 } __packed dparams;
553 struct edd_params *params;
554 uint64_t total;
555
556 params = &dparams.head;
557
558 /* Get disk params */
559 bzero(&dparams, sizeof(dparams));
560 params->len = sizeof(struct edd_params_v3);
561 v86.ctl = V86_FLAGS;
562 v86.addr = DISK_BIOS;
563 v86.eax = CMD_EXT_PARAM;
564 v86.edx = bd->bd_unit;
565 v86.ds = VTOPSEG(&dparams);
566 v86.esi = VTOPOFF(&dparams);
567 v86int();
568
569 if (V86_CY(v86.efl) && ((v86.eax & 0xff00) != 0))
570 return ((v86.eax & 0xff00) >> 8);
571
572 /*
573 * Sector size must be a multiple of 512 bytes.
574 * An alternate test would be to check power of 2,
575 * powerof2(params.sector_size).
576 * 16K is largest read buffer we can use at this time.
577 */
578 if (params->sector_size >= 512 &&
579 params->sector_size <= 16384 &&
580 (params->sector_size % BIOSDISK_SECSIZE) == 0)
581 bd->bd_sectorsize = params->sector_size;
582
583 bd->bd_cyl = params->cylinders;
584 bd->bd_hds = params->heads;
585 bd->bd_sec = params->sectors_per_track;
586
587 if (params->sectors != 0) {
588 total = params->sectors;
589 } else {
590 total = (uint64_t)params->cylinders *
591 params->heads * params->sectors_per_track;
592 }
593 bd->bd_sectors = total;
594
595 return (0);
596 }
597
598 /*
599 * Try to detect a device supported by the legacy int13 BIOS
600 */
601 static bool
bd_int13probe(bdinfo_t * bd)602 bd_int13probe(bdinfo_t *bd)
603 {
604 int edd, ret;
605
606 bd->bd_flags &= ~BD_NO_MEDIA;
607
608 if ((bd->bd_flags & BD_CDROM) != 0) {
609 return (bd_get_diskinfo_cd(bd) == 0);
610 }
611
612 edd = bd_check_extensions(bd->bd_unit);
613 if (edd == 0)
614 bd->bd_flags |= BD_MODEINT13;
615 else if (edd < 0x30)
616 bd->bd_flags |= BD_MODEEDD1;
617 else
618 bd->bd_flags |= BD_MODEEDD3;
619
620 /* Default sector size */
621 if (bd->bd_sectorsize == 0)
622 bd->bd_sectorsize = BIOSDISK_SECSIZE;
623
624 /*
625 * Test if the floppy device is present, so we can avoid receiving
626 * bogus information from bd_get_diskinfo_std().
627 */
628 if (bd->bd_unit < 0x80) {
629 /* reset disk */
630 bd_reset_disk(bd->bd_unit);
631
632 /* Get disk type */
633 v86.ctl = V86_FLAGS;
634 v86.addr = DISK_BIOS;
635 v86.eax = CMD_DRIVE_TYPE;
636 v86.edx = bd->bd_unit;
637 v86int();
638 if (V86_CY(v86.efl) || (v86.eax & 0x300) == 0)
639 return (false);
640 }
641
642 ret = 1;
643 if (edd != 0)
644 ret = bd_get_diskinfo_ext(bd);
645 if (ret != 0 || bd->bd_sectors == 0)
646 ret = bd_get_diskinfo_std(bd);
647
648 if (ret != 0 && bd->bd_unit < 0x80) {
649 /* Set defaults for 1.44 floppy */
650 bd->bd_cyl = 80;
651 bd->bd_hds = 2;
652 bd->bd_sec = 18;
653 bd->bd_sectors = 2880;
654 /* Since we are there, there most likely is no media */
655 bd->bd_flags |= BD_NO_MEDIA;
656 ret = 0;
657 }
658
659 if (ret != 0) {
660 if (bd->bd_sectors != 0 && edd != 0) {
661 bd->bd_sec = 63;
662 bd->bd_hds = 255;
663 bd->bd_cyl =
664 (bd->bd_sectors + bd->bd_sec * bd->bd_hds - 1) /
665 bd->bd_sec * bd->bd_hds;
666 } else {
667 const char *dv_name;
668
669 if ((bd->bd_flags & BD_FLOPPY) != 0)
670 dv_name = biosfd.dv_name;
671 else
672 dv_name = bioshd.dv_name;
673
674 printf("Can not get information about %s unit %#x\n",
675 dv_name, bd->bd_unit);
676 return (false);
677 }
678 }
679
680 if (bd->bd_sec == 0)
681 bd->bd_sec = 63;
682 if (bd->bd_hds == 0)
683 bd->bd_hds = 255;
684
685 if (bd->bd_sectors == 0)
686 bd->bd_sectors = (uint64_t)bd->bd_cyl * bd->bd_hds * bd->bd_sec;
687
688 DPRINTF("unit 0x%x geometry %d/%d/%d\n", bd->bd_unit, bd->bd_cyl,
689 bd->bd_hds, bd->bd_sec);
690
691 return (true);
692 }
693
694 static int
bd_count(bdinfo_list_t * bdi)695 bd_count(bdinfo_list_t *bdi)
696 {
697 bdinfo_t *bd;
698 int i;
699
700 i = 0;
701 STAILQ_FOREACH(bd, bdi, bd_link)
702 i++;
703 return (i);
704 }
705
706 /*
707 * Print information about disks
708 */
709 static int
bd_print_common(struct devsw * dev,bdinfo_list_t * bdi,int verbose)710 bd_print_common(struct devsw *dev, bdinfo_list_t *bdi, int verbose)
711 {
712 char line[80];
713 struct disk_devdesc devd;
714 bdinfo_t *bd;
715 int i, ret = 0;
716 char drive;
717
718 if (STAILQ_EMPTY(bdi))
719 return (0);
720
721 printf("%s devices:", dev->dv_name);
722 if ((ret = pager_output("\n")) != 0)
723 return (ret);
724
725 i = -1;
726 STAILQ_FOREACH(bd, bdi, bd_link) {
727 i++;
728
729 switch (dev->dv_type) {
730 case DEVT_FD:
731 drive = 'A';
732 break;
733 case DEVT_CD:
734 drive = 'C' + bd_count(&hdinfo);
735 break;
736 default:
737 drive = 'C';
738 break;
739 }
740
741 snprintf(line, sizeof(line),
742 " %s%d: BIOS drive %c (%s%ju X %u):\n",
743 dev->dv_name, i, drive + i,
744 (bd->bd_flags & BD_NO_MEDIA) == BD_NO_MEDIA ?
745 "no media, " : "",
746 (uintmax_t)bd->bd_sectors,
747 bd->bd_sectorsize);
748 if ((ret = pager_output(line)) != 0)
749 break;
750
751 if ((bd->bd_flags & BD_NO_MEDIA) == BD_NO_MEDIA)
752 continue;
753
754 if (dev->dv_type != DEVT_DISK)
755 continue;
756
757 devd.dd.d_dev = dev;
758 devd.dd.d_unit = i;
759 devd.d_slice = D_SLICENONE;
760 devd.d_partition = D_PARTNONE;
761 if (disk_open(&devd,
762 bd->bd_sectorsize * bd->bd_sectors,
763 bd->bd_sectorsize) == 0) {
764 snprintf(line, sizeof(line), " %s%d",
765 dev->dv_name, i);
766 ret = disk_print(&devd, line, verbose);
767 disk_close(&devd);
768 if (ret != 0)
769 break;
770 }
771 }
772 return (ret);
773 }
774
775 static int
fd_print(int verbose)776 fd_print(int verbose)
777 {
778 return (bd_print_common(&biosfd, &fdinfo, verbose));
779 }
780
781 static int
bd_print(int verbose)782 bd_print(int verbose)
783 {
784 return (bd_print_common(&bioshd, &hdinfo, verbose));
785 }
786
787 static int
cd_print(int verbose)788 cd_print(int verbose)
789 {
790 return (bd_print_common(&bioscd, &cdinfo, verbose));
791 }
792
793 /*
794 * Read disk size from partition.
795 * This is needed to work around buggy BIOS systems returning
796 * wrong (truncated) disk media size.
797 * During bd_probe() we tested if the multiplication of bd_sectors
798 * would overflow so it should be safe to perform here.
799 */
800 static uint64_t
bd_disk_get_sectors(struct disk_devdesc * dev)801 bd_disk_get_sectors(struct disk_devdesc *dev)
802 {
803 bdinfo_t *bd;
804 struct disk_devdesc disk;
805 uint64_t size;
806
807 bd = bd_get_bdinfo(&dev->dd);
808 if (bd == NULL)
809 return (0);
810
811 disk.dd.d_dev = dev->dd.d_dev;
812 disk.dd.d_unit = dev->dd.d_unit;
813 disk.d_slice = D_SLICENONE;
814 disk.d_partition = D_PARTNONE;
815 disk.d_offset = 0;
816
817 size = bd->bd_sectors * bd->bd_sectorsize;
818 if (disk_open(&disk, size, bd->bd_sectorsize) == 0) {
819 (void) disk_ioctl(&disk, DIOCGMEDIASIZE, &size);
820 disk_close(&disk);
821 }
822 return (size / bd->bd_sectorsize);
823 }
824
825 /*
826 * Attempt to open the disk described by (dev) for use by (f).
827 *
828 * Note that the philosophy here is "give them exactly what
829 * they ask for". This is necessary because being too "smart"
830 * about what the user might want leads to complications.
831 * (eg. given no slice or partition value, with a disk that is
832 * sliced - are they after the first BSD slice, or the DOS
833 * slice before it?)
834 */
835 static int
bd_open(struct open_file * f,...)836 bd_open(struct open_file *f, ...)
837 {
838 bdinfo_t *bd;
839 struct disk_devdesc *dev;
840 va_list ap;
841 int rc;
842
843 va_start(ap, f);
844 dev = va_arg(ap, struct disk_devdesc *);
845 va_end(ap);
846
847 bd = bd_get_bdinfo(&dev->dd);
848 if (bd == NULL)
849 return (EIO);
850
851 if ((bd->bd_flags & BD_NO_MEDIA) == BD_NO_MEDIA) {
852 if (!bd_int13probe(bd))
853 return (EIO);
854 if ((bd->bd_flags & BD_NO_MEDIA) == BD_NO_MEDIA)
855 return (EIO);
856 }
857 if (bd->bd_bcache == NULL)
858 bd->bd_bcache = bcache_allocate();
859
860 if (bd->bd_open == 0)
861 bd->bd_sectors = bd_disk_get_sectors(dev);
862 bd->bd_open++;
863
864 rc = 0;
865 if (dev->dd.d_dev->dv_type == DEVT_DISK) {
866 rc = disk_open(dev, bd->bd_sectors * bd->bd_sectorsize,
867 bd->bd_sectorsize);
868 if (rc != 0) {
869 bd->bd_open--;
870 if (bd->bd_open == 0) {
871 bcache_free(bd->bd_bcache);
872 bd->bd_bcache = NULL;
873 }
874 }
875 }
876 return (rc);
877 }
878
879 static int
bd_close(struct open_file * f)880 bd_close(struct open_file *f)
881 {
882 struct disk_devdesc *dev;
883 bdinfo_t *bd;
884 int rc = 0;
885
886 dev = (struct disk_devdesc *)f->f_devdata;
887 bd = bd_get_bdinfo(&dev->dd);
888 if (bd == NULL)
889 return (EIO);
890
891 bd->bd_open--;
892 if (bd->bd_open == 0) {
893 bcache_free(bd->bd_bcache);
894 bd->bd_bcache = NULL;
895 }
896 if (dev->dd.d_dev->dv_type == DEVT_DISK)
897 rc = disk_close(dev);
898 return (rc);
899 }
900
901 static int
bd_ioctl(struct open_file * f,u_long cmd,void * data)902 bd_ioctl(struct open_file *f, u_long cmd, void *data)
903 {
904 bdinfo_t *bd;
905 struct disk_devdesc *dev;
906 int rc;
907
908 dev = (struct disk_devdesc *)f->f_devdata;
909 bd = bd_get_bdinfo(&dev->dd);
910 if (bd == NULL)
911 return (EIO);
912
913 if (dev->dd.d_dev->dv_type == DEVT_DISK) {
914 rc = disk_ioctl(dev, cmd, data);
915 if (rc != ENOTTY)
916 return (rc);
917 }
918
919 switch (cmd) {
920 case DIOCGSECTORSIZE:
921 *(uint32_t *)data = bd->bd_sectorsize;
922 break;
923 case DIOCGMEDIASIZE:
924 *(uint64_t *)data = bd->bd_sectors * bd->bd_sectorsize;
925 break;
926 default:
927 return (ENOTTY);
928 }
929 return (0);
930 }
931
932 static int
bd_strategy(void * devdata,int rw,daddr_t dblk,size_t size,char * buf,size_t * rsize)933 bd_strategy(void *devdata, int rw, daddr_t dblk, size_t size,
934 char *buf, size_t *rsize)
935 {
936 bdinfo_t *bd;
937 struct bcache_devdata bcd;
938 struct disk_devdesc *dev;
939 daddr_t offset;
940
941 dev = (struct disk_devdesc *)devdata;
942 bd = bd_get_bdinfo(&dev->dd);
943 if (bd == NULL)
944 return (EINVAL);
945
946 bcd.dv_strategy = bd_realstrategy;
947 bcd.dv_devdata = devdata;
948 bcd.dv_cache = bd->bd_bcache;
949
950 offset = 0;
951 if (dev->dd.d_dev->dv_type == DEVT_DISK) {
952
953 offset = dev->d_offset * bd->bd_sectorsize;
954 offset /= BIOSDISK_SECSIZE;
955 }
956 return (bcache_strategy(&bcd, rw, dblk + offset, size,
957 buf, rsize));
958 }
959
960 static int
bd_realstrategy(void * devdata,int rw,daddr_t dblk,size_t size,char * buf,size_t * rsize)961 bd_realstrategy(void *devdata, int rw, daddr_t dblk, size_t size,
962 char *buf, size_t *rsize)
963 {
964 struct disk_devdesc *dev = (struct disk_devdesc *)devdata;
965 bdinfo_t *bd;
966 uint64_t disk_blocks, offset, d_offset;
967 size_t blks, blkoff, bsize, bio_size, rest;
968 caddr_t bbuf = NULL;
969 int rc;
970
971 bd = bd_get_bdinfo(&dev->dd);
972 if (bd == NULL || (bd->bd_flags & BD_NO_MEDIA) == BD_NO_MEDIA)
973 return (EIO);
974
975 /*
976 * First make sure the IO size is a multiple of 512 bytes. While we do
977 * process partial reads below, the strategy mechanism is built
978 * assuming IO is a multiple of 512B blocks. If the request is not
979 * a multiple of 512B blocks, it has to be some sort of bug.
980 */
981 if (size == 0 || (size % BIOSDISK_SECSIZE) != 0) {
982 printf("bd_strategy: %d bytes I/O not multiple of %d\n",
983 size, BIOSDISK_SECSIZE);
984 return (EIO);
985 }
986
987 DPRINTF("open_disk %p", dev);
988
989 offset = dblk * BIOSDISK_SECSIZE;
990 dblk = offset / bd->bd_sectorsize;
991 blkoff = offset % bd->bd_sectorsize;
992
993 /*
994 * Check the value of the size argument. We do have quite small
995 * heap (64MB), but we do not know good upper limit, so we check against
996 * INT_MAX here. This will also protect us against possible overflows
997 * while translating block count to bytes.
998 */
999 if (size > INT_MAX) {
1000 DPRINTF("too large I/O: %zu bytes", size);
1001 return (EIO);
1002 }
1003
1004 blks = size / bd->bd_sectorsize;
1005 if (blks == 0 || (size % bd->bd_sectorsize) != 0)
1006 blks++;
1007
1008 if (dblk > dblk + blks)
1009 return (EIO);
1010
1011 if (rsize)
1012 *rsize = 0;
1013
1014 /*
1015 * Get disk blocks, this value is either for whole disk or for
1016 * partition.
1017 */
1018 d_offset = 0;
1019 disk_blocks = 0;
1020 if (dev->dd.d_dev->dv_type == DEVT_DISK) {
1021 if (disk_ioctl(dev, DIOCGMEDIASIZE, &disk_blocks) == 0) {
1022 /* DIOCGMEDIASIZE does return bytes. */
1023 disk_blocks /= bd->bd_sectorsize;
1024 }
1025 d_offset = dev->d_offset;
1026 }
1027 if (disk_blocks == 0)
1028 disk_blocks = bd->bd_sectors * (bd->bd_sectorsize /
1029 BIOSDISK_SECSIZE) - d_offset;
1030
1031 /* Validate source block address. */
1032 if (dblk < d_offset || dblk >= d_offset + disk_blocks)
1033 return (EIO);
1034
1035 /*
1036 * Truncate if we are crossing disk or partition end.
1037 */
1038 if (dblk + blks >= d_offset + disk_blocks) {
1039 blks = d_offset + disk_blocks - dblk;
1040 size = blks * bd->bd_sectorsize;
1041 DPRINTF("short I/O %d", blks);
1042 }
1043
1044 bio_size = min(BIO_BUFFER_SIZE, size);
1045 while (bio_size > bd->bd_sectorsize) {
1046 bbuf = bio_alloc(bio_size);
1047 if (bbuf != NULL)
1048 break;
1049 bio_size -= bd->bd_sectorsize;
1050 }
1051 if (bbuf == NULL) {
1052 bio_size = V86_IO_BUFFER_SIZE;
1053 if (bio_size / bd->bd_sectorsize == 0)
1054 panic("BUG: Real mode buffer is too small");
1055
1056 /* Use alternate 4k buffer */
1057 bbuf = PTOV(V86_IO_BUFFER);
1058 }
1059 rest = size;
1060 rc = 0;
1061 while (blks > 0) {
1062 int x = min(blks, bio_size / bd->bd_sectorsize);
1063
1064 switch (rw & F_MASK) {
1065 case F_READ:
1066 DPRINTF("read %d from %lld to %p", x, dblk, buf);
1067 bsize = bd->bd_sectorsize * x - blkoff;
1068 if (rest < bsize)
1069 bsize = rest;
1070
1071 if ((rc = bd_io(dev, bd, dblk, x, bbuf, BD_RD)) != 0) {
1072 rc = EIO;
1073 goto error;
1074 }
1075
1076 bcopy(bbuf + blkoff, buf, bsize);
1077 break;
1078 case F_WRITE :
1079 DPRINTF("write %d from %lld to %p", x, dblk, buf);
1080 if (blkoff != 0) {
1081 /*
1082 * We got offset to sector, read 1 sector to
1083 * bbuf.
1084 */
1085 x = 1;
1086 bsize = bd->bd_sectorsize - blkoff;
1087 bsize = min(bsize, rest);
1088 rc = bd_io(dev, bd, dblk, x, bbuf, BD_RD);
1089 } else if (rest < bd->bd_sectorsize) {
1090 /*
1091 * The remaining block is not full
1092 * sector. Read 1 sector to bbuf.
1093 */
1094 x = 1;
1095 bsize = rest;
1096 rc = bd_io(dev, bd, dblk, x, bbuf, BD_RD);
1097 } else {
1098 /* We can write full sector(s). */
1099 bsize = bd->bd_sectorsize * x;
1100 }
1101 /*
1102 * Put your Data In, Put your Data out,
1103 * Put your Data In, and shake it all about
1104 */
1105 bcopy(buf, bbuf + blkoff, bsize);
1106 if ((rc = bd_io(dev, bd, dblk, x, bbuf, BD_WR)) != 0) {
1107 rc = EIO;
1108 goto error;
1109 }
1110
1111 break;
1112 default:
1113 /* DO NOTHING */
1114 rc = EROFS;
1115 goto error;
1116 }
1117
1118 blkoff = 0;
1119 buf += bsize;
1120 rest -= bsize;
1121 blks -= x;
1122 dblk += x;
1123 }
1124
1125 if (rsize != NULL)
1126 *rsize = size;
1127 error:
1128 if (bbuf != PTOV(V86_IO_BUFFER))
1129 bio_free(bbuf, bio_size);
1130 return (rc);
1131 }
1132
1133 static int
bd_edd_io(bdinfo_t * bd,daddr_t dblk,int blks,caddr_t dest,int dowrite)1134 bd_edd_io(bdinfo_t *bd, daddr_t dblk, int blks, caddr_t dest,
1135 int dowrite)
1136 {
1137 static struct edd_packet packet;
1138
1139 packet.len = sizeof(struct edd_packet);
1140 packet.count = blks;
1141 packet.off = VTOPOFF(dest);
1142 packet.seg = VTOPSEG(dest);
1143 packet.lba = dblk;
1144 v86.ctl = V86_FLAGS;
1145 v86.addr = DISK_BIOS;
1146 if (dowrite == BD_WR)
1147 v86.eax = CMD_WRITE_LBA; /* maybe Write with verify 0x4302? */
1148 else
1149 v86.eax = CMD_READ_LBA;
1150 v86.edx = bd->bd_unit;
1151 v86.ds = VTOPSEG(&packet);
1152 v86.esi = VTOPOFF(&packet);
1153 v86int();
1154 if (V86_CY(v86.efl))
1155 return (v86.eax >> 8);
1156 return (0);
1157 }
1158
1159 static int
bd_chs_io(bdinfo_t * bd,daddr_t dblk,int blks,caddr_t dest,int dowrite)1160 bd_chs_io(bdinfo_t *bd, daddr_t dblk, int blks, caddr_t dest,
1161 int dowrite)
1162 {
1163 uint32_t x, bpc, cyl, hd, sec;
1164
1165 bpc = bd->bd_sec * bd->bd_hds; /* blocks per cylinder */
1166 x = dblk;
1167 cyl = x / bpc; /* block # / blocks per cylinder */
1168 x %= bpc; /* block offset into cylinder */
1169 hd = x / bd->bd_sec; /* offset / blocks per track */
1170 sec = x % bd->bd_sec; /* offset into track */
1171
1172 /* correct sector number for 1-based BIOS numbering */
1173 sec++;
1174
1175 if (cyl > 1023) {
1176 /* CHS doesn't support cylinders > 1023. */
1177 return (1);
1178 }
1179
1180 v86.ctl = V86_FLAGS;
1181 v86.addr = DISK_BIOS;
1182 if (dowrite == BD_WR)
1183 v86.eax = CMD_WRITE_CHS | blks;
1184 else
1185 v86.eax = CMD_READ_CHS | blks;
1186 v86.ecx = ((cyl & 0xff) << 8) | ((cyl & 0x300) >> 2) | sec;
1187 v86.edx = (hd << 8) | bd->bd_unit;
1188 v86.es = VTOPSEG(dest);
1189 v86.ebx = VTOPOFF(dest);
1190 v86int();
1191 if (V86_CY(v86.efl))
1192 return (v86.eax >> 8);
1193 return (0);
1194 }
1195
1196 static void
bd_io_workaround(bdinfo_t * bd)1197 bd_io_workaround(bdinfo_t *bd)
1198 {
1199 uint8_t buf[8 * 1024];
1200
1201 bd_edd_io(bd, 0xffffffff, 1, (caddr_t)buf, BD_RD);
1202 }
1203
1204 static int
bd_io(struct disk_devdesc * dev,bdinfo_t * bd,daddr_t dblk,int blks,caddr_t dest,int dowrite)1205 bd_io(struct disk_devdesc *dev, bdinfo_t *bd, daddr_t dblk, int blks,
1206 caddr_t dest, int dowrite)
1207 {
1208 int result, retry;
1209
1210 /* Just in case some idiot actually tries to read/write -1 blocks... */
1211 if (blks < 0)
1212 return (-1);
1213
1214 /*
1215 * Workaround for a problem with some HP ProLiant BIOS failing to work
1216 * out the boot disk after installation. hrs and kuriyama discovered
1217 * this problem with an HP ProLiant DL320e Gen 8 with a 3TB HDD, and
1218 * discovered that an int13h call seems to cause a buffer overrun in
1219 * the bios. The problem is alleviated by doing an extra read before
1220 * the buggy read. It is not immediately known whether other models
1221 * are similarly affected.
1222 * Loop retrying the operation a couple of times. The BIOS
1223 * may also retry.
1224 */
1225 if (dowrite == BD_RD && dblk >= 0x100000000)
1226 bd_io_workaround(bd);
1227 for (retry = 0; retry < 3; retry++) {
1228 if (bd->bd_flags & BD_MODEEDD)
1229 result = bd_edd_io(bd, dblk, blks, dest, dowrite);
1230 else
1231 result = bd_chs_io(bd, dblk, blks, dest, dowrite);
1232
1233 if (result == 0) {
1234 if (bd->bd_flags & BD_NO_MEDIA)
1235 bd->bd_flags &= ~BD_NO_MEDIA;
1236 break;
1237 }
1238
1239 bd_reset_disk(bd->bd_unit);
1240
1241 /*
1242 * Error codes:
1243 * 20h controller failure
1244 * 31h no media in drive (IBM/MS INT 13 extensions)
1245 * 80h no media in drive, VMWare (Fusion)
1246 * There is no reason to repeat the IO with errors above.
1247 */
1248 if (result == 0x20 || result == 0x31 || result == 0x80) {
1249 bd->bd_flags |= BD_NO_MEDIA;
1250 break;
1251 }
1252 }
1253
1254 if (result != 0 && (bd->bd_flags & BD_NO_MEDIA) == 0) {
1255 if (dowrite == BD_WR) {
1256 printf("%s%d: Write %d sector(s) from %p (0x%x) "
1257 "to %lld: 0x%x\n", dev->dd.d_dev->dv_name,
1258 dev->dd.d_unit, blks, dest, VTOP(dest), dblk,
1259 result);
1260 } else {
1261 printf("%s%d: Read %d sector(s) from %lld to %p "
1262 "(0x%x): 0x%x\n", dev->dd.d_dev->dv_name,
1263 dev->dd.d_unit, blks, dblk, dest, VTOP(dest),
1264 result);
1265 }
1266 }
1267
1268 return (result);
1269 }
1270
1271 /*
1272 * Return the BIOS geometry of a given "fixed drive" in a format
1273 * suitable for the legacy bootinfo structure. Since the kernel is
1274 * expecting raw int 0x13/0x8 values for N_BIOS_GEOM drives, we
1275 * prefer to get the information directly, rather than rely on being
1276 * able to put it together from information already maintained for
1277 * different purposes and for a probably different number of drives.
1278 *
1279 * For valid drives, the geometry is expected in the format (31..0)
1280 * "000000cc cccccccc hhhhhhhh 00ssssss"; and invalid drives are
1281 * indicated by returning the geometry of a "1.2M" PC-format floppy
1282 * disk. And, incidentally, what is returned is not the geometry as
1283 * such but the highest valid cylinder, head, and sector numbers.
1284 */
1285 uint32_t
bd_getbigeom(int bunit)1286 bd_getbigeom(int bunit)
1287 {
1288
1289 v86.ctl = V86_FLAGS;
1290 v86.addr = DISK_BIOS;
1291 v86.eax = CMD_READ_PARAM;
1292 v86.edx = 0x80 + bunit;
1293 v86int();
1294 if (V86_CY(v86.efl))
1295 return (0x4f010f);
1296 return (((v86.ecx & 0xc0) << 18) | ((v86.ecx & 0xff00) << 8) |
1297 (v86.edx & 0xff00) | (v86.ecx & 0x3f));
1298 }
1299
1300 /*
1301 * Return a suitable dev_t value for (dev).
1302 *
1303 * In the case where it looks like (dev) is a SCSI disk, we allow the number of
1304 * IDE disks to be specified in $num_ide_disks. There should be a Better Way.
1305 */
1306 int
bd_getdev(struct i386_devdesc * d)1307 bd_getdev(struct i386_devdesc *d)
1308 {
1309 struct disk_devdesc *dev;
1310 bdinfo_t *bd;
1311 int biosdev;
1312 int major;
1313 int rootdev;
1314 char *nip, *cp;
1315 int i, unit, slice, partition;
1316
1317 /* XXX: Assume partition 'a'. */
1318 slice = 0;
1319 partition = 0;
1320
1321 dev = (struct disk_devdesc *)d;
1322 bd = bd_get_bdinfo(&dev->dd);
1323 if (bd == NULL)
1324 return (-1);
1325
1326 biosdev = bd_unit2bios(d);
1327 DPRINTF("unit %d BIOS device %d", dev->dd.d_unit, biosdev);
1328 if (biosdev == -1) /* not a BIOS device */
1329 return (-1);
1330
1331 if (dev->dd.d_dev->dv_type == DEVT_DISK) {
1332 if (disk_open(dev, bd->bd_sectors * bd->bd_sectorsize,
1333 bd->bd_sectorsize) != 0) /* oops, not a viable device */
1334 return (-1);
1335 else
1336 disk_close(dev);
1337 slice = dev->d_slice + 1;
1338 partition = dev->d_partition;
1339 }
1340
1341 if (biosdev < 0x80) {
1342 /* floppy (or emulated floppy) or ATAPI device */
1343 if (bd->bd_type == DT_ATAPI) {
1344 /* is an ATAPI disk */
1345 major = WFDMAJOR;
1346 } else {
1347 /* is a floppy disk */
1348 major = FDMAJOR;
1349 }
1350 } else {
1351 /* assume an IDE disk */
1352 major = WDMAJOR;
1353 }
1354 /* default root disk unit number */
1355 unit = biosdev & 0x7f;
1356
1357 if (dev->dd.d_dev->dv_type == DEVT_CD) {
1358 /*
1359 * XXX: Need to examine device spec here to figure out if
1360 * SCSI or ATAPI. No idea on how to figure out device number.
1361 * All we can really pass to the kernel is what bus and device
1362 * on which bus we were booted from, which dev_t isn't well
1363 * suited to since those number don't match to unit numbers
1364 * very well. We may just need to engage in a hack where
1365 * we pass -C to the boot args if we are the boot device.
1366 */
1367 major = ACDMAJOR;
1368 unit = 0; /* XXX */
1369 }
1370
1371 /* XXX a better kludge to set the root disk unit number */
1372 if ((nip = getenv("root_disk_unit")) != NULL) {
1373 i = strtol(nip, &cp, 0);
1374 /* check for parse error */
1375 if ((cp != nip) && (*cp == 0))
1376 unit = i;
1377 }
1378
1379 rootdev = MAKEBOOTDEV(major, slice, unit, partition);
1380 DPRINTF("dev is 0x%x\n", rootdev);
1381 return (rootdev);
1382 }
1383