xref: /openbsd-src/sys/arch/amd64/stand/libsa/softraid_amd64.c (revision 855f8c0393a31efa1a61652932a7d72cbafe4cfa)
1 /*	$OpenBSD: softraid_amd64.c,v 1.8 2022/08/12 20:17:46 stsp Exp $	*/
2 
3 /*
4  * Copyright (c) 2012 Joel Sing <jsing@openbsd.org>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #include <sys/param.h>
20 #include <sys/queue.h>
21 #include <sys/disklabel.h>
22 #include <sys/reboot.h>
23 
24 #include <dev/biovar.h>
25 #include <dev/softraidvar.h>
26 
27 #include <lib/libsa/aes_xts.h>
28 #include <lib/libsa/softraid.h>
29 #include <lib/libz/zlib.h>
30 
31 #include "libsa.h"
32 #include "disk.h"
33 #include "softraid_amd64.h"
34 
35 static int gpt_chk_mbr(struct dos_partition *, u_int64_t);
36 static uint64_t findopenbsd_gpt(struct sr_boot_volume *, const char **);
37 
38 void
srprobe_meta_opt_load(struct sr_metadata * sm,struct sr_meta_opt_head * som)39 srprobe_meta_opt_load(struct sr_metadata *sm, struct sr_meta_opt_head *som)
40 {
41 	struct sr_meta_opt_hdr	*omh;
42 	struct sr_meta_opt_item *omi;
43 #if 0
44 	u_int8_t checksum[MD5_DIGEST_LENGTH];
45 #endif
46 	int			i;
47 
48 	/* Process optional metadata. */
49 	omh = (struct sr_meta_opt_hdr *)((u_int8_t *)(sm + 1) +
50 	    sizeof(struct sr_meta_chunk) * sm->ssdi.ssd_chunk_no);
51 	for (i = 0; i < sm->ssdi.ssd_opt_no; i++) {
52 
53 #ifdef BIOS_DEBUG
54 		printf("Found optional metadata of type %u, length %u\n",
55 		    omh->som_type, omh->som_length);
56 #endif
57 
58 		/* Unsupported old fixed length optional metadata. */
59 		if (omh->som_length == 0) {
60 			omh = (struct sr_meta_opt_hdr *)((void *)omh +
61 			    SR_OLD_META_OPT_SIZE);
62 			continue;
63 		}
64 
65 		/* Load variable length optional metadata. */
66 		omi = alloc(sizeof(struct sr_meta_opt_item));
67 		bzero(omi, sizeof(struct sr_meta_opt_item));
68 		SLIST_INSERT_HEAD(som, omi, omi_link);
69 		omi->omi_som = alloc(omh->som_length);
70 		bzero(omi->omi_som, omh->som_length);
71 		bcopy(omh, omi->omi_som, omh->som_length);
72 
73 #if 0
74 		/* XXX - Validate checksum. */
75 		bcopy(&omi->omi_som->som_checksum, &checksum,
76 		    MD5_DIGEST_LENGTH);
77 		bzero(&omi->omi_som->som_checksum, MD5_DIGEST_LENGTH);
78 		sr_checksum(sc, omi->omi_som,
79 		    &omi->omi_som->som_checksum, omh->som_length);
80 		if (bcmp(&checksum, &omi->omi_som->som_checksum,
81 		    sizeof(checksum)))
82 			panic("%s: invalid optional metadata checksum",
83 			    DEVNAME(sc));
84 #endif
85 
86 		omh = (struct sr_meta_opt_hdr *)((void *)omh +
87 		    omh->som_length);
88 	}
89 }
90 
91 void
srprobe_keydisk_load(struct sr_metadata * sm)92 srprobe_keydisk_load(struct sr_metadata *sm)
93 {
94 	struct sr_meta_opt_hdr	*omh;
95 	struct sr_meta_keydisk	*skm;
96 	struct sr_boot_keydisk	*kd;
97 	int i;
98 
99 	/* Process optional metadata. */
100 	omh = (struct sr_meta_opt_hdr *)((u_int8_t *)(sm + 1) +
101 	    sizeof(struct sr_meta_chunk) * sm->ssdi.ssd_chunk_no);
102 	for (i = 0; i < sm->ssdi.ssd_opt_no; i++) {
103 
104 		/* Unsupported old fixed length optional metadata. */
105 		if (omh->som_length == 0) {
106 			omh = (struct sr_meta_opt_hdr *)((void *)omh +
107 			    SR_OLD_META_OPT_SIZE);
108 			continue;
109 		}
110 
111 		if (omh->som_type != SR_OPT_KEYDISK) {
112 			omh = (struct sr_meta_opt_hdr *)((void *)omh +
113 			    omh->som_length);
114 			continue;
115 		}
116 
117 		kd = alloc(sizeof(struct sr_boot_keydisk));
118 		bcopy(&sm->ssdi.ssd_uuid, &kd->kd_uuid, sizeof(kd->kd_uuid));
119 		skm = (struct sr_meta_keydisk*)omh;
120 		bcopy(&skm->skm_maskkey, &kd->kd_key, sizeof(kd->kd_key));
121 		SLIST_INSERT_HEAD(&sr_keydisks, kd, kd_link);
122 	}
123 }
124 
125 void
srprobe(void)126 srprobe(void)
127 {
128 	struct sr_boot_volume *bv, *bv1, *bv2;
129 	struct sr_boot_chunk *bc, *bc1, *bc2;
130 	struct sr_meta_chunk *mc;
131 	struct sr_metadata *md;
132 	struct diskinfo *dip;
133 	struct partition *pp;
134 	int i, error, volno;
135 	dev_t bsd_dev;
136 	daddr_t off;
137 
138 	/* Probe for softraid volumes. */
139 	SLIST_INIT(&sr_volumes);
140 	SLIST_INIT(&sr_keydisks);
141 
142 	md = alloc(SR_META_SIZE * DEV_BSIZE);
143 
144 	TAILQ_FOREACH(dip, &disklist, list) {
145 
146 		/* Only check hard disks, skip those with I/O errors. */
147 		if ((dip->bios_info.bios_number & 0x80) == 0 ||
148 		    (dip->bios_info.flags & BDI_INVALID))
149 			continue;
150 
151 		/* Make sure disklabel has been read. */
152 		if ((dip->bios_info.flags & (BDI_BADLABEL|BDI_GOODLABEL)) == 0)
153 			continue;
154 
155 		for (i = 0; i < MAXPARTITIONS; i++) {
156 
157 			pp = &dip->disklabel.d_partitions[i];
158 			if (pp->p_fstype != FS_RAID || pp->p_size == 0)
159 				continue;
160 
161 			/* Read softraid metadata. */
162 			bzero(md, SR_META_SIZE * DEV_BSIZE);
163 			off = DL_SECTOBLK(&dip->disklabel, DL_GETPOFFSET(pp));
164 			off += SR_META_OFFSET;
165 			error = dip->diskio(F_READ, dip, off, SR_META_SIZE, md);
166 			if (error)
167 				continue;
168 
169 			/* Is this valid softraid metadata? */
170 			if (md->ssdi.ssd_magic != SR_MAGIC)
171 				continue;
172 
173 			/* XXX - validate checksum. */
174 
175 			/* Handle key disks separately... */
176 			if (md->ssdi.ssd_level == SR_KEYDISK_LEVEL) {
177 				srprobe_keydisk_load(md);
178 				continue;
179 			}
180 
181 			/* Locate chunk-specific metadata for this chunk. */
182 			mc = (struct sr_meta_chunk *)(md + 1);
183 			mc += md->ssdi.ssd_chunk_id;
184 
185 			bc = alloc(sizeof(struct sr_boot_chunk));
186 			bc->sbc_diskinfo = dip;
187 			bc->sbc_disk = dip->bios_info.bios_number;
188 			bc->sbc_part = 'a' + i;
189 
190 			bsd_dev = dip->bios_info.bsd_dev;
191 			bc->sbc_mm = MAKEBOOTDEV(B_TYPE(bsd_dev),
192 			    B_ADAPTOR(bsd_dev), B_CONTROLLER(bsd_dev),
193 			    B_UNIT(bsd_dev), bc->sbc_part - 'a');
194 
195 			bc->sbc_chunk_id = md->ssdi.ssd_chunk_id;
196 			bc->sbc_ondisk = md->ssd_ondisk;
197 			bc->sbc_state = mc->scm_status;
198 
199 			SLIST_FOREACH(bv, &sr_volumes, sbv_link) {
200 				if (bcmp(&md->ssdi.ssd_uuid, &bv->sbv_uuid,
201 				    sizeof(md->ssdi.ssd_uuid)) == 0)
202 					break;
203 			}
204 
205 			if (bv == NULL) {
206 				bv = alloc(sizeof(struct sr_boot_volume));
207 				bzero(bv, sizeof(struct sr_boot_volume));
208 				bv->sbv_level = md->ssdi.ssd_level;
209 				bv->sbv_volid = md->ssdi.ssd_volid;
210 				bv->sbv_chunk_no = md->ssdi.ssd_chunk_no;
211 				bv->sbv_flags = md->ssdi.ssd_vol_flags;
212 				bv->sbv_size = md->ssdi.ssd_size;
213 				bv->sbv_secsize = md->ssdi.ssd_secsize;
214 				bv->sbv_data_blkno = md->ssd_data_blkno;
215 				bcopy(&md->ssdi.ssd_uuid, &bv->sbv_uuid,
216 				    sizeof(md->ssdi.ssd_uuid));
217 				SLIST_INIT(&bv->sbv_chunks);
218 				SLIST_INIT(&bv->sbv_meta_opt);
219 
220 				/* Load optional metadata for this volume. */
221 				srprobe_meta_opt_load(md, &bv->sbv_meta_opt);
222 
223 				/* Maintain volume order. */
224 				bv2 = NULL;
225 				SLIST_FOREACH(bv1, &sr_volumes, sbv_link) {
226 					if (bv1->sbv_volid > bv->sbv_volid)
227 						break;
228 					bv2 = bv1;
229 				}
230 				if (bv2 == NULL)
231 					SLIST_INSERT_HEAD(&sr_volumes, bv,
232 					    sbv_link);
233 				else
234 					SLIST_INSERT_AFTER(bv2, bv, sbv_link);
235 			}
236 
237 			/* Maintain chunk order. */
238 			bc2 = NULL;
239 			SLIST_FOREACH(bc1, &bv->sbv_chunks, sbc_link) {
240 				if (bc1->sbc_chunk_id > bc->sbc_chunk_id)
241 					break;
242 				bc2 = bc1;
243 			}
244 			if (bc2 == NULL)
245 				SLIST_INSERT_HEAD(&bv->sbv_chunks,
246 				    bc, sbc_link);
247 			else
248 				SLIST_INSERT_AFTER(bc2, bc, sbc_link);
249 
250 			bv->sbv_chunks_found++;
251 		}
252 	}
253 
254 	/*
255 	 * Assemble RAID volumes.
256 	 */
257 	volno = 0;
258 	SLIST_FOREACH(bv, &sr_volumes, sbv_link) {
259 
260 		/* Skip if this is a hotspare "volume". */
261 		if (bv->sbv_level == SR_HOTSPARE_LEVEL &&
262 		    bv->sbv_chunk_no == 1)
263 			continue;
264 
265 		/* Determine current ondisk version. */
266 		bv->sbv_ondisk = 0;
267 		SLIST_FOREACH(bc, &bv->sbv_chunks, sbc_link) {
268 			if (bc->sbc_ondisk > bv->sbv_ondisk)
269 				bv->sbv_ondisk = bc->sbc_ondisk;
270 		}
271 		SLIST_FOREACH(bc, &bv->sbv_chunks, sbc_link) {
272 			if (bc->sbc_ondisk != bv->sbv_ondisk)
273 				bc->sbc_state = BIOC_SDOFFLINE;
274 		}
275 
276 		/* XXX - Check for duplicate chunks. */
277 
278 		/*
279 		 * Validate that volume has sufficient chunks for
280 		 * read-only access.
281 		 *
282 		 * XXX - check chunk states.
283 		 */
284 		bv->sbv_state = BIOC_SVOFFLINE;
285 		switch (bv->sbv_level) {
286 		case 0:
287 		case 'C':
288 		case 'c':
289 			if (bv->sbv_chunk_no == bv->sbv_chunks_found)
290 				bv->sbv_state = BIOC_SVONLINE;
291 			break;
292 
293 		case 1:
294 		case 0x1C:
295 			if (bv->sbv_chunk_no == bv->sbv_chunks_found)
296 				bv->sbv_state = BIOC_SVONLINE;
297 			else if (bv->sbv_chunks_found > 0)
298 				bv->sbv_state = BIOC_SVDEGRADED;
299 			break;
300 		}
301 
302 		bv->sbv_unit = volno++;
303 		if (bv->sbv_state != BIOC_SVOFFLINE)
304 			printf(" sr%d%s", bv->sbv_unit,
305 			    bv->sbv_flags & BIOC_SCBOOTABLE ? "*" : "");
306 	}
307 
308 	explicit_bzero(md, SR_META_SIZE * DEV_BSIZE);
309 	free(md, SR_META_SIZE * DEV_BSIZE);
310 }
311 
312 int
sr_strategy(struct sr_boot_volume * bv,int rw,daddr_t blk,size_t size,void * buf,size_t * rsize)313 sr_strategy(struct sr_boot_volume *bv, int rw, daddr_t blk, size_t size,
314     void *buf, size_t *rsize)
315 {
316 	struct diskinfo *sr_dip, *dip;
317 	struct sr_boot_chunk *bc;
318 	struct aes_xts_ctx ctx;
319 	size_t i, j, nsect;
320 	daddr_t blkno;
321 	u_char iv[8];
322 	u_char *bp;
323 	int err;
324 
325 	/* We only support read-only softraid. */
326 	if (rw != F_READ)
327 		return ENOTSUP;
328 
329 	/* Partition offset within softraid volume. */
330 	sr_dip = (struct diskinfo *)bv->sbv_diskinfo;
331 	blk += DL_SECTOBLK(&sr_dip->disklabel,
332 	    sr_dip->disklabel.d_partitions[bv->sbv_part - 'a'].p_offset);
333 
334 	if (bv->sbv_level == 0) {
335 		return ENOTSUP;
336 	} else if (bv->sbv_level == 1) {
337 
338 		/* Select first online chunk. */
339 		SLIST_FOREACH(bc, &bv->sbv_chunks, sbc_link)
340 			if (bc->sbc_state == BIOC_SDONLINE)
341 				break;
342 		if (bc == NULL)
343 			return EIO;
344 
345 		dip = (struct diskinfo *)bc->sbc_diskinfo;
346 		dip->bsddev = bc->sbc_mm;
347 		blk += bv->sbv_data_blkno;
348 
349 		/* XXX - If I/O failed we should try another chunk... */
350 		return dip->strategy(dip, rw, blk, size, buf, rsize);
351 
352 	} else if (bv->sbv_level == 'C' || bv->sbv_level == 0x1C) {
353 
354 		/* Select first online chunk. */
355 		SLIST_FOREACH(bc, &bv->sbv_chunks, sbc_link)
356 			if (bc->sbc_state == BIOC_SDONLINE)
357 				break;
358 		if (bc == NULL)
359 			return EIO;
360 
361 		dip = (struct diskinfo *)bc->sbc_diskinfo;
362 		dip->bsddev = bc->sbc_mm;
363 
364 		/* XXX - select correct key. */
365 		aes_xts_setkey(&ctx, (u_char *)bv->sbv_keys, 64);
366 
367 		nsect = (size + DEV_BSIZE - 1) / DEV_BSIZE;
368 		for (i = 0; i < nsect; i++) {
369 			blkno = blk + i;
370 			bp = ((u_char *)buf) + i * DEV_BSIZE;
371 			err = dip->strategy(dip, rw, bv->sbv_data_blkno + blkno,
372 			    DEV_BSIZE, bp, NULL);
373 			if (err != 0)
374 				return err;
375 
376 			bcopy(&blkno, iv, sizeof(blkno));
377 			aes_xts_reinit(&ctx, iv);
378 			for (j = 0; j < DEV_BSIZE; j += AES_XTS_BLOCKSIZE)
379 				aes_xts_decrypt(&ctx, bp + j);
380 		}
381 		if (rsize != NULL)
382 			*rsize = nsect * DEV_BSIZE;
383 
384 		return err;
385 
386 	} else
387 		return ENOTSUP;
388 }
389 
390 /*
391  * Returns 0 if the MBR with the provided partition array is a GPT protective
392  * MBR, and returns 1 otherwise. A GPT protective MBR would have one and only
393  * one MBR partition, an EFI partition that either covers the whole disk or as
394  * much of it as is possible with a 32bit size field.
395  *
396  * Taken from kern/subr_disk.c.
397  *
398  * NOTE: MS always uses a size of UINT32_MAX for the EFI partition!**
399  */
400 static int
gpt_chk_mbr(struct dos_partition * dp,u_int64_t dsize)401 gpt_chk_mbr(struct dos_partition *dp, u_int64_t dsize)
402 {
403 	struct dos_partition *dp2;
404 	int efi, found, i;
405 	u_int32_t psize;
406 
407 	found = efi = 0;
408 	for (dp2=dp, i=0; i < NDOSPART; i++, dp2++) {
409 		if (dp2->dp_typ == DOSPTYP_UNUSED)
410 			continue;
411 		found++;
412 		if (dp2->dp_typ != DOSPTYP_EFI)
413 			continue;
414 		if (letoh32(dp2->dp_start) != GPTSECTOR)
415 			continue;
416 		psize = letoh32(dp2->dp_size);
417 		if (psize <= (dsize - GPTSECTOR) || psize == UINT32_MAX)
418 			efi++;
419 	}
420 	if (found == 1 && efi == 1)
421 		return (0);
422 
423 	return (1);
424 }
425 
426 static uint64_t
findopenbsd_gpt(struct sr_boot_volume * bv,const char ** err)427 findopenbsd_gpt(struct sr_boot_volume *bv, const char **err)
428 {
429 	struct			 gpt_header gh;
430 	int			 i, part, found;
431 	uint64_t		 lba;
432 	uint32_t		 orig_csum, new_csum;
433 	uint32_t		 ghsize, ghpartsize, ghpartnum, ghpartspersec;
434 	uint32_t		 gpsectors;
435 	const char		 openbsd_uuid_code[] = GPT_UUID_OPENBSD;
436 	struct gpt_partition	 gp;
437 	static struct uuid	*openbsd_uuid = NULL, openbsd_uuid_space;
438 	u_char		 	*buf;
439 
440 	/* Prepare OpenBSD UUID */
441 	if (openbsd_uuid == NULL) {
442 		/* XXX: should be replaced by uuid_dec_be() */
443 		memcpy(&openbsd_uuid_space, openbsd_uuid_code,
444 		    sizeof(openbsd_uuid_space));
445 		openbsd_uuid_space.time_low =
446 		    betoh32(openbsd_uuid_space.time_low);
447 		openbsd_uuid_space.time_mid =
448 		    betoh16(openbsd_uuid_space.time_mid);
449 		openbsd_uuid_space.time_hi_and_version =
450 		    betoh16(openbsd_uuid_space.time_hi_and_version);
451 
452 		openbsd_uuid = &openbsd_uuid_space;
453 	}
454 
455 	if (bv->sbv_secsize > 4096) {
456 		*err = "disk sector > 4096 bytes\n";
457 		return (-1);
458 	}
459 	buf = alloc(bv->sbv_secsize);
460 	if (buf == NULL) {
461 		*err = "out of memory\n";
462 		return (-1);
463 	}
464 	bzero(buf, bv->sbv_secsize);
465 
466 	/* GPT Header */
467 	lba = GPTSECTOR;
468 	sr_strategy(bv, F_READ, lba * (bv->sbv_secsize / DEV_BSIZE), DEV_BSIZE,
469 	    buf, NULL);
470 	memcpy(&gh, buf, sizeof(gh));
471 
472 	/* Check signature */
473 	if (letoh64(gh.gh_sig) != GPTSIGNATURE) {
474 		*err = "bad GPT signature\n";
475 		free(buf, bv->sbv_secsize);
476 		return (-1);
477 	}
478 
479 	if (letoh32(gh.gh_rev) != GPTREVISION) {
480 		*err = "bad GPT revision\n";
481 		free(buf, bv->sbv_secsize);
482 		return (-1);
483 	}
484 
485 	ghsize = letoh32(gh.gh_size);
486 	if (ghsize < GPTMINHDRSIZE || ghsize > sizeof(struct gpt_header)) {
487 		*err = "bad GPT header size\n";
488 		free(buf, bv->sbv_secsize);
489 		return (-1);
490 	}
491 
492 	/* Check checksum */
493 	orig_csum = gh.gh_csum;
494 	gh.gh_csum = 0;
495 	new_csum = crc32(0, (unsigned char *)&gh, ghsize);
496 	gh.gh_csum = orig_csum;
497 	if (letoh32(orig_csum) != new_csum) {
498 		*err = "bad GPT header checksum\n";
499 		free(buf, bv->sbv_secsize);
500 		return (-1);
501 	}
502 
503 	lba = letoh64(gh.gh_part_lba);
504 	ghpartsize = letoh32(gh.gh_part_size);
505 	ghpartspersec = bv->sbv_secsize / ghpartsize;
506 	ghpartnum = letoh32(gh.gh_part_num);
507 	gpsectors = (ghpartnum + ghpartspersec - 1) / ghpartspersec;
508 	new_csum = crc32(0L, Z_NULL, 0);
509 	found = 0;
510 	for (i = 0; i < gpsectors; i++, lba++) {
511 		sr_strategy(bv, F_READ, lba * (bv->sbv_secsize / DEV_BSIZE),
512 		    bv->sbv_secsize, buf, NULL);
513 		for (part = 0; part < ghpartspersec; part++) {
514 			if (ghpartnum == 0)
515 				break;
516 			new_csum = crc32(new_csum, buf + part * sizeof(gp),
517 			    sizeof(gp));
518 			ghpartnum--;
519 			if (found)
520 				continue;
521 			memcpy(&gp, buf + part * sizeof(gp), sizeof(gp));
522 			if (memcmp(&gp.gp_type, openbsd_uuid,
523 			    sizeof(struct uuid)) == 0)
524 				found = 1;
525 		}
526 	}
527 
528 	free(buf, bv->sbv_secsize);
529 
530 	if (new_csum != letoh32(gh.gh_part_csum)) {
531 		*err = "bad GPT entries checksum\n";
532 		return (-1);
533 	}
534 	if (found)
535 		return (letoh64(gp.gp_lba_start));
536 
537 	return (-1);
538 }
539 
540 const char *
sr_getdisklabel(struct sr_boot_volume * bv,struct disklabel * label)541 sr_getdisklabel(struct sr_boot_volume *bv, struct disklabel *label)
542 {
543 	struct dos_partition *dp;
544 	struct dos_mbr mbr;
545 	const char *err = NULL;
546 	u_int start = 0;
547 	char buf[DEV_BSIZE];
548 	int i;
549 
550 	/* Check for MBR to determine partition offset. */
551 	bzero(&mbr, sizeof(mbr));
552 	sr_strategy(bv, F_READ, DOSBBSECTOR, sizeof(mbr), &mbr, NULL);
553 	if (gpt_chk_mbr(mbr.dmbr_parts, bv->sbv_size /
554 		    (bv->sbv_secsize / DEV_BSIZE)) == 0) {
555 		start = findopenbsd_gpt(bv, &err);
556 		if (start == (u_int)-1) {
557 			if (err != NULL)
558 				return (err);
559 			return "no OpenBSD partition\n";
560 		}
561 	} else if (mbr.dmbr_sign == DOSMBR_SIGNATURE) {
562 
563 		/* Search for OpenBSD partition */
564 		for (i = 0; i < NDOSPART; i++) {
565 			dp = &mbr.dmbr_parts[i];
566 			if (!dp->dp_size)
567 				continue;
568 			if (dp->dp_typ == DOSPTYP_OPENBSD) {
569 				start = dp->dp_start;
570 				break;
571 			}
572 		}
573 	}
574 
575 	/* Read the disklabel. */
576 	sr_strategy(bv, F_READ,
577 	    start * (bv->sbv_secsize / DEV_BSIZE) + DOS_LABELSECTOR,
578 	    sizeof(struct disklabel), buf, NULL);
579 
580 #ifdef BIOS_DEBUG
581 	printf("sr_getdisklabel: magic %lx\n",
582 	    ((struct disklabel *)buf)->d_magic);
583 	for (i = 0; i < MAXPARTITIONS; i++)
584 		printf("part %c: type = %d, size = %d, offset = %d\n", 'a' + i,
585 		    (int)((struct disklabel *)buf)->d_partitions[i].p_fstype,
586 		    (int)((struct disklabel *)buf)->d_partitions[i].p_size,
587 		    (int)((struct disklabel *)buf)->d_partitions[i].p_offset);
588 #endif
589 
590 	/* Fill in disklabel */
591 	return (getdisklabel(buf, label));
592 }
593