xref: /freebsd/stand/i386/zfsboot/zfsboot.c (revision a03411e84728e9b267056fd31c7d1d9d1dc1b01e)
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 #include <stand.h>
18 
19 #include <sys/param.h>
20 #include <sys/errno.h>
21 #include <sys/diskmbr.h>
22 #ifdef GPT
23 #include <sys/gpt.h>
24 #endif
25 #include <sys/reboot.h>
26 #include <sys/queue.h>
27 #ifdef LOADER_ZFS_SUPPORT
28 #include <sys/zfs_bootenv.h>
29 #endif
30 
31 #include <machine/bootinfo.h>
32 #include <machine/elf.h>
33 #include <machine/pc/bios.h>
34 
35 #include <stdarg.h>
36 #include <stddef.h>
37 
38 #include <a.out.h>
39 #include "bootstrap.h"
40 #include "libi386.h"
41 #include <btxv86.h>
42 
43 #include "lib.h"
44 #include "rbx.h"
45 #include "cons.h"
46 #include "bootargs.h"
47 #include "disk.h"
48 #include "part.h"
49 #include "paths.h"
50 
51 #include "libzfs.h"
52 
53 #define	ARGS			0x900
54 #define	NOPT			14
55 #define	NDEV			3
56 
57 #define	BIOS_NUMDRIVES		0x475
58 #define	DRV_HARD		0x80
59 #define	DRV_MASK		0x7f
60 
61 #define	TYPE_AD			0
62 #define	TYPE_DA			1
63 #define	TYPE_MAXHARD		TYPE_DA
64 #define	TYPE_FD			2
65 
66 extern uint32_t _end;
67 
68 static const char optstr[NOPT] = "DhaCcdgmnpqrsv"; /* Also 'P', 'S' */
69 static const unsigned char flags[NOPT] = {
70     RBX_DUAL,
71     RBX_SERIAL,
72     RBX_ASKNAME,
73     RBX_CDROM,
74     RBX_CONFIG,
75     RBX_KDB,
76     RBX_GDB,
77     RBX_MUTE,
78     RBX_NOINTR,
79     RBX_PAUSE,
80     RBX_QUIET,
81     RBX_DFLTROOT,
82     RBX_SINGLE,
83     RBX_VERBOSE
84 };
85 uint32_t opts;
86 
87 /*
88  * Paths to try loading before falling back to the boot2 prompt.
89  *
90  * /boot/zfsloader must be tried before /boot/loader in order to remain
91  * backward compatible with ZFS boot environments where /boot/loader exists
92  * but does not have ZFS support, which was the case before FreeBSD 12.
93  *
94  * If no loader is found, try to load a kernel directly instead.
95  */
96 static const struct string {
97 	const char *p;
98 	size_t len;
99 } loadpath[] = {
100 	{ PATH_LOADER_ZFS, sizeof(PATH_LOADER_ZFS) },
101 	{ PATH_LOADER, sizeof(PATH_LOADER) },
102 	{ PATH_KERNEL, sizeof(PATH_KERNEL) },
103 };
104 
105 static const unsigned char dev_maj[NDEV] = {30, 4, 2};
106 
107 static struct i386_devdesc *bdev;
108 static char cmd[512];
109 static char cmddup[512];
110 static char kname[1024];
111 static int comspeed = SIOSPD;
112 static struct bootinfo bootinfo;
113 static uint32_t bootdev;
114 static struct zfs_boot_args zfsargs;
115 #ifdef LOADER_GELI_SUPPORT
116 static struct geli_boot_args geliargs;
117 #endif
118 
119 extern vm_offset_t high_heap_base;
120 extern uint32_t	bios_basemem, bios_extmem, high_heap_size;
121 
122 static char *heap_top;
123 static char *heap_bottom;
124 
125 void exit(int);
126 static void i386_zfs_probe(void);
127 static void load(void);
128 static int parse_cmd(void);
129 
130 #ifdef LOADER_GELI_SUPPORT
131 #include "geliboot.h"
132 static char gelipw[GELI_PW_MAXLEN];
133 #endif
134 
135 struct arch_switch archsw;	/* MI/MD interface boundary */
136 static char boot_devname[2 * ZFS_MAXNAMELEN + 8]; /* disk or pool:dataset */
137 
138 struct devsw *devsw[] = {
139 	&bioshd,
140 #if defined(LOADER_ZFS_SUPPORT)
141 	&zfs_dev,
142 #endif
143 	NULL
144 };
145 
146 struct fs_ops *file_system[] = {
147 #if defined(LOADER_ZFS_SUPPORT)
148 	&zfs_fsops,
149 #endif
150 #if defined(LOADER_UFS_SUPPORT)
151 	&ufs_fsops,
152 #endif
153 	NULL
154 };
155 
156 caddr_t
157 ptov(uintptr_t x)
158 {
159 	return (PTOV(x));
160 }
161 
162 int main(void);
163 
164 int
165 main(void)
166 {
167 	unsigned i;
168 	int auto_boot, fd, nextboot = 0;
169 	struct disk_devdesc *devdesc;
170 
171 	bios_getmem();
172 
173 	if (high_heap_size > 0) {
174 		heap_top = PTOV(high_heap_base + high_heap_size);
175 		heap_bottom = PTOV(high_heap_base);
176 	} else {
177 		heap_bottom = (char *)
178 		    (roundup2(__base + (int32_t)&_end, 0x10000) - __base);
179 		heap_top = (char *)PTOV(bios_basemem);
180 	}
181 	setheap(heap_bottom, heap_top);
182 
183 	/*
184 	 * Initialise the block cache. Set the upper limit.
185 	 */
186 	bcache_init(32768, 512);
187 
188 	archsw.arch_autoload = NULL;
189 	archsw.arch_getdev = i386_getdev;
190 	archsw.arch_copyin = NULL;
191 	archsw.arch_copyout = NULL;
192 	archsw.arch_readin = NULL;
193 	archsw.arch_isainb = NULL;
194 	archsw.arch_isaoutb = NULL;
195 	archsw.arch_zfs_probe = i386_zfs_probe;
196 
197 	bootinfo.bi_version = BOOTINFO_VERSION;
198 	bootinfo.bi_size = sizeof(bootinfo);
199 	bootinfo.bi_basemem = bios_basemem / 1024;
200 	bootinfo.bi_extmem = bios_extmem / 1024;
201 	bootinfo.bi_memsizes_valid++;
202 	bootinfo.bi_bios_dev = *(uint8_t *)PTOV(ARGS);
203 
204 	/* Set up fall back device name. */
205 	snprintf(boot_devname, sizeof (boot_devname), "disk%d:",
206 	    bd_bios2unit(bootinfo.bi_bios_dev));
207 
208 	/* Set up currdev variable to have hooks in place. */
209 	env_setenv("currdev", EV_VOLATILE, "", gen_setcurrdev,
210 	    env_nounset);
211 
212 	devinit();
213 
214 	/* XXX assumes this will be a disk, but it looks likely give above */
215 	disk_parsedev((struct devdesc **)&devdesc, boot_devname, NULL);
216 
217 	bootdev = MAKEBOOTDEV(dev_maj[DEVT_DISK], devdesc->d_slice + 1,
218 	    devdesc->dd.d_unit,
219 	    devdesc->d_partition >= 0 ? devdesc->d_partition : 0xff);
220 	free(devdesc);
221 
222 	/*
223 	 * devformat() can be called only after dv_init
224 	 */
225 	if (bdev != NULL && bdev->dd.d_dev->dv_type == DEVT_ZFS) {
226 		/* set up proper device name string for ZFS */
227 		strncpy(boot_devname, devformat(&bdev->dd), sizeof (boot_devname));
228 		if (zfs_get_bootonce(bdev, OS_BOOTONCE, cmd,
229 		    sizeof(cmd)) == 0) {
230 			nvlist_t *benv;
231 
232 			nextboot = 1;
233 			memcpy(cmddup, cmd, sizeof(cmd));
234 			if (parse_cmd()) {
235 				if (!OPT_CHECK(RBX_QUIET))
236 					printf("failed to parse bootonce "
237 					    "command\n");
238 				exit(0);
239 			}
240 			if (!OPT_CHECK(RBX_QUIET))
241 				printf("zfs bootonce: %s\n", cmddup);
242 
243 			if (zfs_get_bootenv(bdev, &benv) == 0) {
244 				nvlist_add_string(benv, OS_BOOTONCE_USED,
245 				    cmddup);
246 				zfs_set_bootenv(bdev, benv);
247 			}
248 			/* Do not process this command twice */
249 			*cmd = 0;
250 		}
251 	}
252 
253 	/* now make sure we have bdev on all cases */
254 	free(bdev);
255 	i386_getdev((void **)&bdev, boot_devname, NULL);
256 
257 	env_setenv("currdev", EV_VOLATILE, boot_devname, gen_setcurrdev,
258 	    env_nounset);
259 
260 	/* Process configuration file */
261 	auto_boot = 1;
262 
263 	fd = open(PATH_CONFIG, O_RDONLY);
264 	if (fd == -1)
265 		fd = open(PATH_DOTCONFIG, O_RDONLY);
266 
267 	if (fd != -1) {
268 		ssize_t cmdlen;
269 
270 		if ((cmdlen = read(fd, cmd, sizeof(cmd))) > 0)
271 			cmd[cmdlen] = '\0';
272 		else
273 			*cmd = '\0';
274 		close(fd);
275 	}
276 
277 	if (*cmd) {
278 		/*
279 		 * Note that parse_cmd() is destructive to cmd[] and we also
280 		 * want to honor RBX_QUIET option that could be present in
281 		 * cmd[].
282 		 */
283 		memcpy(cmddup, cmd, sizeof(cmd));
284 		if (parse_cmd())
285 			auto_boot = 0;
286 		if (!OPT_CHECK(RBX_QUIET))
287 			printf("%s: %s\n", PATH_CONFIG, cmddup);
288 		/* Do not process this command twice */
289 		*cmd = 0;
290 	}
291 
292 	/* Do not risk waiting at the prompt forever. */
293 	if (nextboot && !auto_boot)
294 		exit(0);
295 
296 	if (auto_boot && !*kname) {
297 		/*
298 		 * Iterate through the list of loader and kernel paths,
299 		 * trying to load. If interrupted by a keypress, or in case of
300 		 * failure, drop the user to the boot2 prompt.
301 		 */
302 		for (i = 0; i < nitems(loadpath); i++) {
303 			memcpy(kname, loadpath[i].p, loadpath[i].len);
304 			if (keyhit(3))
305 				break;
306 			load();
307 		}
308 	}
309 
310 	/* Present the user with the boot2 prompt. */
311 
312 	for (;;) {
313 		if (!auto_boot || !OPT_CHECK(RBX_QUIET)) {
314 			printf("\nFreeBSD/x86 boot\n");
315 			printf("Default: %s%s\nboot: ", boot_devname, kname);
316 		}
317 		if (ioctrl & IO_SERIAL)
318 			sio_flush();
319 		if (!auto_boot || keyhit(5))
320 			getstr(cmd, sizeof(cmd));
321 		else if (!auto_boot || !OPT_CHECK(RBX_QUIET))
322 			putchar('\n');
323 		auto_boot = 0;
324 		if (parse_cmd())
325 			putchar('\a');
326 		else
327 			load();
328 	}
329 }
330 
331 /* XXX - Needed for btxld to link the boot2 binary; do not remove. */
332 void
333 exit(int x)
334 {
335 	__exit(x);
336 }
337 
338 static void
339 load(void)
340 {
341 	union {
342 		struct exec ex;
343 		Elf32_Ehdr eh;
344 	} hdr;
345 	static Elf32_Phdr ep[2];
346 	static Elf32_Shdr es[2];
347 	caddr_t p;
348 	uint32_t addr, x;
349 	int fd, fmt, i, j;
350 	ssize_t size;
351 
352 	if ((fd = open(kname, O_RDONLY)) == -1) {
353 		printf("\nCan't find %s\n", kname);
354 		return;
355 	}
356 
357 	size = sizeof(hdr);
358 	if (read(fd, &hdr, sizeof (hdr)) != size) {
359 		close(fd);
360 		return;
361 	}
362 	if (N_GETMAGIC(hdr.ex) == ZMAGIC) {
363 		fmt = 0;
364 	} else if (IS_ELF(hdr.eh)) {
365 		fmt = 1;
366 	} else {
367 		printf("Invalid %s\n", "format");
368 		close(fd);
369 		return;
370 	}
371 	if (fmt == 0) {
372 		addr = hdr.ex.a_entry & 0xffffff;
373 		p = PTOV(addr);
374 		lseek(fd, PAGE_SIZE, SEEK_SET);
375 		size = hdr.ex.a_text;
376 		if (read(fd, p, hdr.ex.a_text) != size) {
377 			close(fd);
378 			return;
379 		}
380 		p += roundup2(hdr.ex.a_text, PAGE_SIZE);
381 		size = hdr.ex.a_data;
382 		if (read(fd, p, hdr.ex.a_data) != size) {
383 			close(fd);
384 			return;
385 		}
386 		p += hdr.ex.a_data + roundup2(hdr.ex.a_bss, PAGE_SIZE);
387 		bootinfo.bi_symtab = VTOP(p);
388 		memcpy(p, &hdr.ex.a_syms, sizeof(hdr.ex.a_syms));
389 		p += sizeof(hdr.ex.a_syms);
390 		if (hdr.ex.a_syms) {
391 			size = hdr.ex.a_syms;
392 			if (read(fd, p, hdr.ex.a_syms) != size) {
393 				close(fd);
394 				return;
395 			}
396 			p += hdr.ex.a_syms;
397 			size = sizeof (int);
398 			if (read(fd, p, sizeof (int)) != size) {
399 				close(fd);
400 				return;
401 			}
402 			x = *(uint32_t *)p;
403 			p += sizeof(int);
404 			x -= sizeof(int);
405 			size = x;
406 			if (read(fd, p, x) != size) {
407 				close(fd);
408 				return;
409 			}
410 			p += x;
411 		}
412 	} else {
413 		lseek(fd, hdr.eh.e_phoff, SEEK_SET);
414 		for (j = i = 0; i < hdr.eh.e_phnum && j < 2; i++) {
415 			size = sizeof (ep[0]);
416 			if (read(fd, ep + j, sizeof (ep[0])) != size) {
417 				close(fd);
418 				return;
419 			}
420 			if (ep[j].p_type == PT_LOAD)
421 				j++;
422 		}
423 		for (i = 0; i < 2; i++) {
424 			p = PTOV(ep[i].p_paddr & 0xffffff);
425 			lseek(fd, ep[i].p_offset, SEEK_SET);
426 			size = ep[i].p_filesz;
427 			if (read(fd, p, ep[i].p_filesz) != size) {
428 				close(fd);
429 				return;
430 			}
431 		}
432 		p += roundup2(ep[1].p_memsz, PAGE_SIZE);
433 		bootinfo.bi_symtab = VTOP(p);
434 		if (hdr.eh.e_shnum == hdr.eh.e_shstrndx + 3) {
435 			lseek(fd, hdr.eh.e_shoff +
436 			    sizeof (es[0]) * (hdr.eh.e_shstrndx + 1),
437 			    SEEK_SET);
438 			size = sizeof(es);
439 			if (read(fd, &es, sizeof (es)) != size) {
440 				close(fd);
441 				return;
442 			}
443 			for (i = 0; i < 2; i++) {
444 				memcpy(p, &es[i].sh_size,
445 				    sizeof(es[i].sh_size));
446 				p += sizeof(es[i].sh_size);
447 				lseek(fd, es[i].sh_offset, SEEK_SET);
448 				size = es[i].sh_size;
449 				if (read(fd, p, es[i].sh_size) != size) {
450 					close(fd);
451 					return;
452 				}
453 				p += es[i].sh_size;
454 			}
455 		}
456 		addr = hdr.eh.e_entry & 0xffffff;
457 	}
458 	close(fd);
459 
460 	bootinfo.bi_esymtab = VTOP(p);
461 	bootinfo.bi_kernelname = VTOP(kname);
462 #ifdef LOADER_GELI_SUPPORT
463 	explicit_bzero(gelipw, sizeof(gelipw));
464 #endif
465 
466 	if (bdev->dd.d_dev->dv_type == DEVT_ZFS) {
467 		zfsargs.size = sizeof(zfsargs);
468 		zfsargs.pool = bdev->zfs.pool_guid;
469 		zfsargs.root = bdev->zfs.root_guid;
470 #ifdef LOADER_GELI_SUPPORT
471 		export_geli_boot_data(&zfsargs.gelidata);
472 #endif
473 		/*
474 		 * Note that the zfsargs struct is passed by value, not by
475 		 * pointer. Code in btxldr.S copies the values from the entry
476 		 * stack to a fixed location within loader(8) at startup due
477 		 * to the presence of KARGS_FLAGS_EXTARG.
478 		 */
479 		__exec((caddr_t)addr, RB_BOOTINFO | (opts & RBX_MASK),
480 		    bootdev,
481 		    KARGS_FLAGS_ZFS | KARGS_FLAGS_EXTARG,
482 		    (uint32_t)bdev->zfs.pool_guid,
483 		    (uint32_t)(bdev->zfs.pool_guid >> 32),
484 		    VTOP(&bootinfo),
485 		    zfsargs);
486 	} else {
487 #ifdef LOADER_GELI_SUPPORT
488 		geliargs.size = sizeof(geliargs);
489 		export_geli_boot_data(&geliargs.gelidata);
490 #endif
491 
492 		/*
493 		 * Note that the geliargs struct is passed by value, not by
494 		 * pointer. Code in btxldr.S copies the values from the entry
495 		 * stack to a fixed location within loader(8) at startup due
496 		 * to the presence of the KARGS_FLAGS_EXTARG flag.
497 		 */
498 		__exec((caddr_t)addr, RB_BOOTINFO | (opts & RBX_MASK),
499 		    bootdev,
500 #ifdef LOADER_GELI_SUPPORT
501 		    KARGS_FLAGS_GELI | KARGS_FLAGS_EXTARG, 0, 0,
502 		    VTOP(&bootinfo), geliargs
503 #else
504 		    0, 0, 0, VTOP(&bootinfo)
505 #endif
506 		    );
507 	}
508 }
509 
510 static int
511 mount_root(char *arg)
512 {
513 	char *root;
514 	struct i386_devdesc *ddesc;
515 	uint8_t part;
516 
517 	if (asprintf(&root, "%s:", arg) < 0)
518 		return (1);
519 
520 	if (i386_getdev((void **)&ddesc, root, NULL)) {
521 		free(root);
522 		return (1);
523 	}
524 
525 	/* we should have new device descriptor, free old and replace it. */
526 	free(bdev);
527 	bdev = ddesc;
528 	if (bdev->dd.d_dev->dv_type == DEVT_DISK) {
529 		if (bdev->disk.d_partition == -1)
530 			part = 0xff;
531 		else
532 			part = bdev->disk.d_partition;
533 		bootdev = MAKEBOOTDEV(dev_maj[bdev->dd.d_dev->dv_type],
534 		    bdev->disk.d_slice + 1, bdev->dd.d_unit, part);
535 		bootinfo.bi_bios_dev = bd_unit2bios(bdev);
536 	}
537 	strncpy(boot_devname, root, sizeof (boot_devname));
538 	setenv("currdev", root, 1);
539 	free(root);
540 	return (0);
541 }
542 
543 static void
544 fs_list(char *arg)
545 {
546 	int fd;
547 	struct dirent *d;
548 	char line[80];
549 
550 	fd = open(arg, O_RDONLY);
551 	if (fd < 0)
552 		return;
553 	pager_open();
554 	while ((d = readdirfd(fd)) != NULL) {
555 		sprintf(line, "%s\n", d->d_name);
556 		if (pager_output(line))
557 			break;
558 	}
559 	pager_close();
560 	close(fd);
561 }
562 
563 static int
564 parse_cmd(void)
565 {
566 	char *arg = cmd;
567 	char *ep, *p, *q;
568 	const char *cp;
569 	char line[80];
570 	int c, i, j;
571 
572 	while ((c = *arg++)) {
573 		if (c == ' ' || c == '\t' || c == '\n')
574 			continue;
575 		for (p = arg; *p && *p != '\n' && *p != ' ' && *p != '\t'; p++)
576 			;
577 		ep = p;
578 		if (*p)
579 			*p++ = 0;
580 		if (c == '-') {
581 			while ((c = *arg++)) {
582 				if (c == 'P') {
583 					if (*(uint8_t *)PTOV(0x496) & 0x10) {
584 						cp = "yes";
585 					} else {
586 						opts |= OPT_SET(RBX_DUAL);
587 						opts |= OPT_SET(RBX_SERIAL);
588 						cp = "no";
589 					}
590 					printf("Keyboard: %s\n", cp);
591 					continue;
592 				} else if (c == 'S') {
593 					j = 0;
594 					while ((unsigned int)
595 					    (i = *arg++ - '0') <= 9)
596 						j = j * 10 + i;
597 					if (j > 0 && i == -'0') {
598 						comspeed = j;
599 						break;
600 					}
601 					/*
602 					 * Fall through to error below
603 					 * ('S' not in optstr[]).
604 					 */
605 				}
606 				for (i = 0; c != optstr[i]; i++)
607 					if (i == NOPT - 1)
608 						return (-1);
609 				opts ^= OPT_SET(flags[i]);
610 			}
611 			ioctrl = OPT_CHECK(RBX_DUAL) ? (IO_SERIAL|IO_KEYBOARD) :
612 			    OPT_CHECK(RBX_SERIAL) ? IO_SERIAL : IO_KEYBOARD;
613 			if (ioctrl & IO_SERIAL) {
614 				if (sio_init(115200 / comspeed) != 0)
615 					ioctrl &= ~IO_SERIAL;
616 			}
617 		} if (c == '?') {
618 			printf("\n");
619 			if (*arg == '\0')
620 				arg = (char *)"/";
621 			fs_list(arg);
622 			zfs_list(arg);
623 			return (-1);
624 		} else {
625 			char *ptr;
626 			printf("\n");
627 			arg--;
628 
629 			/*
630 			 * Report pool status if the comment is 'status'. Lets
631 			 * hope no-one wants to load /status as a kernel.
632 			 */
633 			if (strcmp(arg, "status") == 0) {
634 				pager_open();
635 				for (i = 0; devsw[i] != NULL; i++) {
636 					if (devsw[i]->dv_print != NULL) {
637 						if (devsw[i]->dv_print(1))
638 							break;
639 					} else {
640 						snprintf(line, sizeof(line),
641 						    "%s: (unknown)\n",
642 						    devsw[i]->dv_name);
643 						if (pager_output(line))
644 							break;
645 					}
646 				}
647 				pager_close();
648 				return (-1);
649 			}
650 
651 			/*
652 			 * If there is "zfs:" prefix simply ignore it.
653 			 */
654 			ptr = arg;
655 			if (strncmp(ptr, "zfs:", 4) == 0)
656 				ptr += 4;
657 
658 			/*
659 			 * If there is a colon, switch pools.
660 			 */
661 			q = strchr(ptr, ':');
662 			if (q) {
663 				*q++ = '\0';
664 				if (mount_root(arg) != 0) {
665 					return (-1);
666 				}
667 				arg = q;
668 			}
669 			if ((i = ep - arg)) {
670 				if ((size_t)i >= sizeof(kname))
671 					return (-1);
672 				memcpy(kname, arg, i + 1);
673 			}
674 		}
675 		arg = p;
676 	}
677 	return (0);
678 }
679 
680 /*
681  * Probe all disks to discover ZFS pools. The idea is to walk all possible
682  * disk devices, however, we also need to identify possible boot pool.
683  * For boot pool detection we have boot disk passed us from BIOS, recorded
684  * in bootinfo.bi_bios_dev.
685  */
686 static void
687 i386_zfs_probe(void)
688 {
689 	char devname[32];
690 	int boot_unit;
691 	struct i386_devdesc dev;
692 	uint64_t pool_guid = 0;
693 
694 	dev.dd.d_dev = &bioshd;
695 	/* Translate bios dev to our unit number. */
696 	boot_unit = bd_bios2unit(bootinfo.bi_bios_dev);
697 
698 	/*
699 	 * Open all the disks we can find and see if we can reconstruct
700 	 * ZFS pools from them.
701 	 */
702 	for (dev.dd.d_unit = 0; bd_unit2bios(&dev) >= 0; dev.dd.d_unit++) {
703 		snprintf(devname, sizeof (devname), "%s%d:", bioshd.dv_name,
704 		    dev.dd.d_unit);
705 		/* If this is not boot disk, use generic probe. */
706 		if (dev.dd.d_unit != boot_unit)
707 			zfs_probe_dev(devname, NULL, true);
708 		else
709 			zfs_probe_dev(devname, &pool_guid, true);
710 
711 		if (pool_guid != 0 && bdev == NULL) {
712 			bdev = malloc(sizeof (struct i386_devdesc));
713 			bzero(bdev, sizeof (struct i386_devdesc));
714 			bdev->zfs.dd.d_dev = &zfs_dev;
715 			bdev->zfs.pool_guid = pool_guid;
716 		}
717 	}
718 }
719