xref: /freebsd/stand/i386/zfsboot/zfsboot.c (revision a0b9e2e854027e6ff61fb075a1309dbc71c42b54)
1 /*-
2  * Copyright (c) 1998 Robert Nordier
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms are freely
6  * permitted provided that the above copyright notice and this
7  * paragraph and the following disclaimer are duplicated in all
8  * such forms.
9  *
10  * This software is provided "AS IS" and without any express or
11  * implied warranties, including, without limitation, the implied
12  * warranties of merchantability and fitness for a particular
13  * purpose.
14  */
15 
16 #include <sys/cdefs.h>
17 __FBSDID("$FreeBSD$");
18 
19 #include <stand.h>
20 
21 #include <sys/param.h>
22 #include <sys/errno.h>
23 #include <sys/diskmbr.h>
24 #ifdef GPT
25 #include <sys/gpt.h>
26 #endif
27 #include <sys/reboot.h>
28 #include <sys/queue.h>
29 #ifdef LOADER_ZFS_SUPPORT
30 #include <sys/zfs_bootenv.h>
31 #endif
32 
33 #include <machine/bootinfo.h>
34 #include <machine/elf.h>
35 #include <machine/pc/bios.h>
36 
37 #include <stdarg.h>
38 #include <stddef.h>
39 
40 #include <a.out.h>
41 #include "bootstrap.h"
42 #include "libi386.h"
43 #include <btxv86.h>
44 
45 #include "lib.h"
46 #include "rbx.h"
47 #include "cons.h"
48 #include "bootargs.h"
49 #include "disk.h"
50 #include "part.h"
51 #include "paths.h"
52 
53 #include "libzfs.h"
54 
55 #define	ARGS			0x900
56 #define	NOPT			14
57 #define	NDEV			3
58 
59 #define	BIOS_NUMDRIVES		0x475
60 #define	DRV_HARD		0x80
61 #define	DRV_MASK		0x7f
62 
63 #define	TYPE_AD			0
64 #define	TYPE_DA			1
65 #define	TYPE_MAXHARD		TYPE_DA
66 #define	TYPE_FD			2
67 
68 extern uint32_t _end;
69 
70 static const char optstr[NOPT] = "DhaCcdgmnpqrsv"; /* Also 'P', 'S' */
71 static const unsigned char flags[NOPT] = {
72     RBX_DUAL,
73     RBX_SERIAL,
74     RBX_ASKNAME,
75     RBX_CDROM,
76     RBX_CONFIG,
77     RBX_KDB,
78     RBX_GDB,
79     RBX_MUTE,
80     RBX_NOINTR,
81     RBX_PAUSE,
82     RBX_QUIET,
83     RBX_DFLTROOT,
84     RBX_SINGLE,
85     RBX_VERBOSE
86 };
87 uint32_t opts;
88 
89 /*
90  * Paths to try loading before falling back to the boot2 prompt.
91  *
92  * /boot/zfsloader must be tried before /boot/loader in order to remain
93  * backward compatible with ZFS boot environments where /boot/loader exists
94  * but does not have ZFS support, which was the case before FreeBSD 12.
95  *
96  * If no loader is found, try to load a kernel directly instead.
97  */
98 static const struct string {
99 	const char *p;
100 	size_t len;
101 } loadpath[] = {
102 	{ PATH_LOADER_ZFS, sizeof(PATH_LOADER_ZFS) },
103 	{ PATH_LOADER, sizeof(PATH_LOADER) },
104 	{ PATH_KERNEL, sizeof(PATH_KERNEL) },
105 };
106 
107 static const unsigned char dev_maj[NDEV] = {30, 4, 2};
108 
109 static struct i386_devdesc *bdev;
110 static char cmd[512];
111 static char cmddup[512];
112 static char kname[1024];
113 static int comspeed = SIOSPD;
114 static struct bootinfo bootinfo;
115 static uint32_t bootdev;
116 static struct zfs_boot_args zfsargs;
117 #ifdef LOADER_GELI_SUPPORT
118 static struct geli_boot_args geliargs;
119 #endif
120 
121 extern vm_offset_t high_heap_base;
122 extern uint32_t	bios_basemem, bios_extmem, high_heap_size;
123 
124 static char *heap_top;
125 static char *heap_bottom;
126 
127 void exit(int);
128 static void i386_zfs_probe(void);
129 static void load(void);
130 static int parse_cmd(void);
131 
132 #ifdef LOADER_GELI_SUPPORT
133 #include "geliboot.h"
134 static char gelipw[GELI_PW_MAXLEN];
135 #endif
136 
137 struct arch_switch archsw;	/* MI/MD interface boundary */
138 static char boot_devname[2 * ZFS_MAXNAMELEN + 8]; /* disk or pool:dataset */
139 
140 struct devsw *devsw[] = {
141 	&bioshd,
142 #if defined(LOADER_ZFS_SUPPORT)
143 	&zfs_dev,
144 #endif
145 	NULL
146 };
147 
148 struct fs_ops *file_system[] = {
149 #if defined(LOADER_ZFS_SUPPORT)
150 	&zfs_fsops,
151 #endif
152 #if defined(LOADER_UFS_SUPPORT)
153 	&ufs_fsops,
154 #endif
155 	NULL
156 };
157 
158 caddr_t
159 ptov(uintptr_t x)
160 {
161 	return (PTOV(x));
162 }
163 
164 int main(void);
165 
166 int
167 main(void)
168 {
169 	unsigned i;
170 	int auto_boot, fd, nextboot = 0;
171 	struct disk_devdesc devdesc;
172 
173 	bios_getmem();
174 
175 	if (high_heap_size > 0) {
176 		heap_top = PTOV(high_heap_base + high_heap_size);
177 		heap_bottom = PTOV(high_heap_base);
178 	} else {
179 		heap_bottom = (char *)
180 		    (roundup2(__base + (int32_t)&_end, 0x10000) - __base);
181 		heap_top = (char *)PTOV(bios_basemem);
182 	}
183 	setheap(heap_bottom, heap_top);
184 
185 	/*
186 	 * Initialise the block cache. Set the upper limit.
187 	 */
188 	bcache_init(32768, 512);
189 
190 	archsw.arch_autoload = NULL;
191 	archsw.arch_getdev = i386_getdev;
192 	archsw.arch_copyin = NULL;
193 	archsw.arch_copyout = NULL;
194 	archsw.arch_readin = NULL;
195 	archsw.arch_isainb = NULL;
196 	archsw.arch_isaoutb = NULL;
197 	archsw.arch_zfs_probe = i386_zfs_probe;
198 
199 	bootinfo.bi_version = BOOTINFO_VERSION;
200 	bootinfo.bi_size = sizeof(bootinfo);
201 	bootinfo.bi_basemem = bios_basemem / 1024;
202 	bootinfo.bi_extmem = bios_extmem / 1024;
203 	bootinfo.bi_memsizes_valid++;
204 	bootinfo.bi_bios_dev = *(uint8_t *)PTOV(ARGS);
205 
206 	/* Set up fall back device name. */
207 	snprintf(boot_devname, sizeof (boot_devname), "disk%d:",
208 	    bd_bios2unit(bootinfo.bi_bios_dev));
209 
210 	for (i = 0; devsw[i] != NULL; i++)
211 		if (devsw[i]->dv_init != NULL)
212 			(devsw[i]->dv_init)();
213 
214 	disk_parsedev(&devdesc, boot_devname + 4, NULL);
215 
216 	bootdev = MAKEBOOTDEV(dev_maj[DEVT_DISK], devdesc.d_slice + 1,
217 	    devdesc.dd.d_unit,
218 	    devdesc.d_partition >= 0 ? devdesc.d_partition : 0xff);
219 
220 	/*
221 	 * zfs_fmtdev() can be called only after dv_init
222 	 */
223 	if (bdev != NULL && bdev->dd.d_dev->dv_type == DEVT_ZFS) {
224 		/* set up proper device name string for ZFS */
225 		strncpy(boot_devname, zfs_fmtdev(bdev), sizeof (boot_devname));
226 		if (zfs_get_bootonce(bdev, OS_BOOTONCE, cmd,
227 		    sizeof(cmd)) == 0) {
228 			nvlist_t *benv;
229 
230 			nextboot = 1;
231 			memcpy(cmddup, cmd, sizeof(cmd));
232 			if (parse_cmd()) {
233 				if (!OPT_CHECK(RBX_QUIET))
234 					printf("failed to parse bootonce "
235 					    "command\n");
236 				exit(0);
237 			}
238 			if (!OPT_CHECK(RBX_QUIET))
239 				printf("zfs bootonce: %s\n", cmddup);
240 
241 			if (zfs_get_bootenv(bdev, &benv) == 0) {
242 				nvlist_add_string(benv, OS_BOOTONCE_USED,
243 				    cmddup);
244 				zfs_set_bootenv(bdev, benv);
245 			}
246 			/* Do not process this command twice */
247 			*cmd = 0;
248 		}
249 	}
250 
251 	/* now make sure we have bdev on all cases */
252 	free(bdev);
253 	i386_getdev((void **)&bdev, boot_devname, NULL);
254 
255 	env_setenv("currdev", EV_VOLATILE, boot_devname, i386_setcurrdev,
256 	    env_nounset);
257 
258 	/* Process configuration file */
259 	auto_boot = 1;
260 
261 	fd = open(PATH_CONFIG, O_RDONLY);
262 	if (fd == -1)
263 		fd = open(PATH_DOTCONFIG, O_RDONLY);
264 
265 	if (fd != -1) {
266 		ssize_t cmdlen;
267 
268 		if ((cmdlen = read(fd, cmd, sizeof(cmd))) > 0)
269 			cmd[cmdlen] = '\0';
270 		else
271 			*cmd = '\0';
272 		close(fd);
273 	}
274 
275 	if (*cmd) {
276 		/*
277 		 * Note that parse_cmd() is destructive to cmd[] and we also
278 		 * want to honor RBX_QUIET option that could be present in
279 		 * cmd[].
280 		 */
281 		memcpy(cmddup, cmd, sizeof(cmd));
282 		if (parse_cmd())
283 			auto_boot = 0;
284 		if (!OPT_CHECK(RBX_QUIET))
285 			printf("%s: %s\n", PATH_CONFIG, cmddup);
286 		/* Do not process this command twice */
287 		*cmd = 0;
288 	}
289 
290 	/* Do not risk waiting at the prompt forever. */
291 	if (nextboot && !auto_boot)
292 		exit(0);
293 
294 	if (auto_boot && !*kname) {
295 		/*
296 		 * Iterate through the list of loader and kernel paths,
297 		 * trying to load. If interrupted by a keypress, or in case of
298 		 * failure, drop the user to the boot2 prompt.
299 		 */
300 		for (i = 0; i < nitems(loadpath); i++) {
301 			memcpy(kname, loadpath[i].p, loadpath[i].len);
302 			if (keyhit(3))
303 				break;
304 			load();
305 		}
306 	}
307 
308 	/* Present the user with the boot2 prompt. */
309 
310 	for (;;) {
311 		if (!auto_boot || !OPT_CHECK(RBX_QUIET)) {
312 			printf("\nFreeBSD/x86 boot\n");
313 			printf("Default: %s%s\nboot: ", boot_devname, kname);
314 		}
315 		if (ioctrl & IO_SERIAL)
316 			sio_flush();
317 		if (!auto_boot || keyhit(5))
318 			getstr(cmd, sizeof(cmd));
319 		else if (!auto_boot || !OPT_CHECK(RBX_QUIET))
320 			putchar('\n');
321 		auto_boot = 0;
322 		if (parse_cmd())
323 			putchar('\a');
324 		else
325 			load();
326 	}
327 }
328 
329 /* XXX - Needed for btxld to link the boot2 binary; do not remove. */
330 void
331 exit(int x)
332 {
333 	__exit(x);
334 }
335 
336 static void
337 load(void)
338 {
339 	union {
340 		struct exec ex;
341 		Elf32_Ehdr eh;
342 	} hdr;
343 	static Elf32_Phdr ep[2];
344 	static Elf32_Shdr es[2];
345 	caddr_t p;
346 	uint32_t addr, x;
347 	int fd, fmt, i, j;
348 	ssize_t size;
349 
350 	if ((fd = open(kname, O_RDONLY)) == -1) {
351 		printf("\nCan't find %s\n", kname);
352 		return;
353 	}
354 
355 	size = sizeof(hdr);
356 	if (read(fd, &hdr, sizeof (hdr)) != size) {
357 		close(fd);
358 		return;
359 	}
360 	if (N_GETMAGIC(hdr.ex) == ZMAGIC) {
361 		fmt = 0;
362 	} else if (IS_ELF(hdr.eh)) {
363 		fmt = 1;
364 	} else {
365 		printf("Invalid %s\n", "format");
366 		close(fd);
367 		return;
368 	}
369 	if (fmt == 0) {
370 		addr = hdr.ex.a_entry & 0xffffff;
371 		p = PTOV(addr);
372 		lseek(fd, PAGE_SIZE, SEEK_SET);
373 		size = hdr.ex.a_text;
374 		if (read(fd, p, hdr.ex.a_text) != size) {
375 			close(fd);
376 			return;
377 		}
378 		p += roundup2(hdr.ex.a_text, PAGE_SIZE);
379 		size = hdr.ex.a_data;
380 		if (read(fd, p, hdr.ex.a_data) != size) {
381 			close(fd);
382 			return;
383 		}
384 		p += hdr.ex.a_data + roundup2(hdr.ex.a_bss, PAGE_SIZE);
385 		bootinfo.bi_symtab = VTOP(p);
386 		memcpy(p, &hdr.ex.a_syms, sizeof(hdr.ex.a_syms));
387 		p += sizeof(hdr.ex.a_syms);
388 		if (hdr.ex.a_syms) {
389 			size = hdr.ex.a_syms;
390 			if (read(fd, p, hdr.ex.a_syms) != size) {
391 				close(fd);
392 				return;
393 			}
394 			p += hdr.ex.a_syms;
395 			size = sizeof (int);
396 			if (read(fd, p, sizeof (int)) != size) {
397 				close(fd);
398 				return;
399 			}
400 			x = *(uint32_t *)p;
401 			p += sizeof(int);
402 			x -= sizeof(int);
403 			size = x;
404 			if (read(fd, p, x) != size) {
405 				close(fd);
406 				return;
407 			}
408 			p += x;
409 		}
410 	} else {
411 		lseek(fd, hdr.eh.e_phoff, SEEK_SET);
412 		for (j = i = 0; i < hdr.eh.e_phnum && j < 2; i++) {
413 			size = sizeof (ep[0]);
414 			if (read(fd, ep + j, sizeof (ep[0])) != size) {
415 				close(fd);
416 				return;
417 			}
418 			if (ep[j].p_type == PT_LOAD)
419 				j++;
420 		}
421 		for (i = 0; i < 2; i++) {
422 			p = PTOV(ep[i].p_paddr & 0xffffff);
423 			lseek(fd, ep[i].p_offset, SEEK_SET);
424 			size = ep[i].p_filesz;
425 			if (read(fd, p, ep[i].p_filesz) != size) {
426 				close(fd);
427 				return;
428 			}
429 		}
430 		p += roundup2(ep[1].p_memsz, PAGE_SIZE);
431 		bootinfo.bi_symtab = VTOP(p);
432 		if (hdr.eh.e_shnum == hdr.eh.e_shstrndx + 3) {
433 			lseek(fd, hdr.eh.e_shoff +
434 			    sizeof (es[0]) * (hdr.eh.e_shstrndx + 1),
435 			    SEEK_SET);
436 			size = sizeof(es);
437 			if (read(fd, &es, sizeof (es)) != size) {
438 				close(fd);
439 				return;
440 			}
441 			for (i = 0; i < 2; i++) {
442 				memcpy(p, &es[i].sh_size,
443 				    sizeof(es[i].sh_size));
444 				p += sizeof(es[i].sh_size);
445 				lseek(fd, es[i].sh_offset, SEEK_SET);
446 				size = es[i].sh_size;
447 				if (read(fd, p, es[i].sh_size) != size) {
448 					close(fd);
449 					return;
450 				}
451 				p += es[i].sh_size;
452 			}
453 		}
454 		addr = hdr.eh.e_entry & 0xffffff;
455 	}
456 	close(fd);
457 
458 	bootinfo.bi_esymtab = VTOP(p);
459 	bootinfo.bi_kernelname = VTOP(kname);
460 #ifdef LOADER_GELI_SUPPORT
461 	explicit_bzero(gelipw, sizeof(gelipw));
462 #endif
463 
464 	if (bdev->dd.d_dev->dv_type == DEVT_ZFS) {
465 		zfsargs.size = sizeof(zfsargs);
466 		zfsargs.pool = bdev->d_kind.zfs.pool_guid;
467 		zfsargs.root = bdev->d_kind.zfs.root_guid;
468 #ifdef LOADER_GELI_SUPPORT
469 		export_geli_boot_data(&zfsargs.gelidata);
470 #endif
471 		/*
472 		 * Note that the zfsargs struct is passed by value, not by
473 		 * pointer. Code in btxldr.S copies the values from the entry
474 		 * stack to a fixed location within loader(8) at startup due
475 		 * to the presence of KARGS_FLAGS_EXTARG.
476 		 */
477 		__exec((caddr_t)addr, RB_BOOTINFO | (opts & RBX_MASK),
478 		    bootdev,
479 		    KARGS_FLAGS_ZFS | KARGS_FLAGS_EXTARG,
480 		    (uint32_t)bdev->d_kind.zfs.pool_guid,
481 		    (uint32_t)(bdev->d_kind.zfs.pool_guid >> 32),
482 		    VTOP(&bootinfo),
483 		    zfsargs);
484 	} else {
485 #ifdef LOADER_GELI_SUPPORT
486 		geliargs.size = sizeof(geliargs);
487 		export_geli_boot_data(&geliargs.gelidata);
488 #endif
489 
490 		/*
491 		 * Note that the geliargs struct is passed by value, not by
492 		 * pointer. Code in btxldr.S copies the values from the entry
493 		 * stack to a fixed location within loader(8) at startup due
494 		 * to the presence of the KARGS_FLAGS_EXTARG flag.
495 		 */
496 		__exec((caddr_t)addr, RB_BOOTINFO | (opts & RBX_MASK),
497 		    bootdev,
498 #ifdef LOADER_GELI_SUPPORT
499 		    KARGS_FLAGS_GELI | KARGS_FLAGS_EXTARG, 0, 0,
500 		    VTOP(&bootinfo), geliargs
501 #else
502 		    0, 0, 0, VTOP(&bootinfo)
503 #endif
504 		    );
505 	}
506 }
507 
508 static int
509 mount_root(char *arg)
510 {
511 	char *root;
512 	struct i386_devdesc *ddesc;
513 	uint8_t part;
514 
515 	if (asprintf(&root, "%s:", arg) < 0)
516 		return (1);
517 
518 	if (i386_getdev((void **)&ddesc, root, NULL)) {
519 		free(root);
520 		return (1);
521 	}
522 
523 	/* we should have new device descriptor, free old and replace it. */
524 	free(bdev);
525 	bdev = ddesc;
526 	if (bdev->dd.d_dev->dv_type == DEVT_DISK) {
527 		if (bdev->d_kind.biosdisk.partition == -1)
528 			part = 0xff;
529 		else
530 			part = bdev->d_kind.biosdisk.partition;
531 		bootdev = MAKEBOOTDEV(dev_maj[bdev->dd.d_dev->dv_type],
532 		    bdev->d_kind.biosdisk.slice + 1,
533 		    bdev->dd.d_unit, part);
534 		bootinfo.bi_bios_dev = bd_unit2bios(bdev);
535 	}
536 	strncpy(boot_devname, root, sizeof (boot_devname));
537 	setenv("currdev", root, 1);
538 	free(root);
539 	return (0);
540 }
541 
542 static void
543 fs_list(char *arg)
544 {
545 	int fd;
546 	struct dirent *d;
547 	char line[80];
548 
549 	fd = open(arg, O_RDONLY);
550 	if (fd < 0)
551 		return;
552 	pager_open();
553 	while ((d = readdirfd(fd)) != NULL) {
554 		sprintf(line, "%s\n", d->d_name);
555 		if (pager_output(line))
556 			break;
557 	}
558 	pager_close();
559 	close(fd);
560 }
561 
562 static int
563 parse_cmd(void)
564 {
565 	char *arg = cmd;
566 	char *ep, *p, *q;
567 	const char *cp;
568 	char line[80];
569 	int c, i, j;
570 
571 	while ((c = *arg++)) {
572 		if (c == ' ' || c == '\t' || c == '\n')
573 			continue;
574 		for (p = arg; *p && *p != '\n' && *p != ' ' && *p != '\t'; p++)
575 			;
576 		ep = p;
577 		if (*p)
578 			*p++ = 0;
579 		if (c == '-') {
580 			while ((c = *arg++)) {
581 				if (c == 'P') {
582 					if (*(uint8_t *)PTOV(0x496) & 0x10) {
583 						cp = "yes";
584 					} else {
585 						opts |= OPT_SET(RBX_DUAL);
586 						opts |= OPT_SET(RBX_SERIAL);
587 						cp = "no";
588 					}
589 					printf("Keyboard: %s\n", cp);
590 					continue;
591 				} else if (c == 'S') {
592 					j = 0;
593 					while ((unsigned int)
594 					    (i = *arg++ - '0') <= 9)
595 						j = j * 10 + i;
596 					if (j > 0 && i == -'0') {
597 						comspeed = j;
598 						break;
599 					}
600 					/*
601 					 * Fall through to error below
602 					 * ('S' not in optstr[]).
603 					 */
604 				}
605 				for (i = 0; c != optstr[i]; i++)
606 					if (i == NOPT - 1)
607 						return (-1);
608 				opts ^= OPT_SET(flags[i]);
609 			}
610 			ioctrl = OPT_CHECK(RBX_DUAL) ? (IO_SERIAL|IO_KEYBOARD) :
611 			    OPT_CHECK(RBX_SERIAL) ? IO_SERIAL : IO_KEYBOARD;
612 			if (ioctrl & IO_SERIAL) {
613 				if (sio_init(115200 / comspeed) != 0)
614 					ioctrl &= ~IO_SERIAL;
615 			}
616 		} if (c == '?') {
617 			printf("\n");
618 			if (*arg == '\0')
619 				arg = (char *)"/";
620 			fs_list(arg);
621 			zfs_list(arg);
622 			return (-1);
623 		} else {
624 			char *ptr;
625 			printf("\n");
626 			arg--;
627 
628 			/*
629 			 * Report pool status if the comment is 'status'. Lets
630 			 * hope no-one wants to load /status as a kernel.
631 			 */
632 			if (strcmp(arg, "status") == 0) {
633 				pager_open();
634 				for (i = 0; devsw[i] != NULL; i++) {
635 					if (devsw[i]->dv_print != NULL) {
636 						if (devsw[i]->dv_print(1))
637 							break;
638 					} else {
639 						snprintf(line, sizeof(line),
640 						    "%s: (unknown)\n",
641 						    devsw[i]->dv_name);
642 						if (pager_output(line))
643 							break;
644 					}
645 				}
646 				pager_close();
647 				return (-1);
648 			}
649 
650 			/*
651 			 * If there is "zfs:" prefix simply ignore it.
652 			 */
653 			ptr = arg;
654 			if (strncmp(ptr, "zfs:", 4) == 0)
655 				ptr += 4;
656 
657 			/*
658 			 * If there is a colon, switch pools.
659 			 */
660 			q = strchr(ptr, ':');
661 			if (q) {
662 				*q++ = '\0';
663 				if (mount_root(arg) != 0) {
664 					return (-1);
665 				}
666 				arg = q;
667 			}
668 			if ((i = ep - arg)) {
669 				if ((size_t)i >= sizeof(kname))
670 					return (-1);
671 				memcpy(kname, arg, i + 1);
672 			}
673 		}
674 		arg = p;
675 	}
676 	return (0);
677 }
678 
679 /*
680  * Probe all disks to discover ZFS pools. The idea is to walk all possible
681  * disk devices, however, we also need to identify possible boot pool.
682  * For boot pool detection we have boot disk passed us from BIOS, recorded
683  * in bootinfo.bi_bios_dev.
684  */
685 static void
686 i386_zfs_probe(void)
687 {
688 	char devname[32];
689 	int boot_unit;
690 	struct i386_devdesc dev;
691 	uint64_t pool_guid = 0;
692 
693 	dev.dd.d_dev = &bioshd;
694 	/* Translate bios dev to our unit number. */
695 	boot_unit = bd_bios2unit(bootinfo.bi_bios_dev);
696 
697 	/*
698 	 * Open all the disks we can find and see if we can reconstruct
699 	 * ZFS pools from them.
700 	 */
701 	for (dev.dd.d_unit = 0; bd_unit2bios(&dev) >= 0; dev.dd.d_unit++) {
702 		snprintf(devname, sizeof (devname), "%s%d:", bioshd.dv_name,
703 		    dev.dd.d_unit);
704 		/* If this is not boot disk, use generic probe. */
705 		if (dev.dd.d_unit != boot_unit)
706 			zfs_probe_dev(devname, NULL);
707 		else
708 			zfs_probe_dev(devname, &pool_guid);
709 
710 		if (pool_guid != 0 && bdev == NULL) {
711 			bdev = malloc(sizeof (struct i386_devdesc));
712 			bzero(bdev, sizeof (struct i386_devdesc));
713 			bdev->dd.d_dev = &zfs_dev;
714 			bdev->d_kind.zfs.pool_guid = pool_guid;
715 		}
716 	}
717 }
718