xref: /netbsd-src/sys/kern/kern_subr.c (revision deb6f0161a9109e7de9b519dc8dfb9478668dcdd)
1 /*	$NetBSD: kern_subr.c,v 1.220 2018/10/07 11:24:16 mlelstv Exp $	*/
2 
3 /*-
4  * Copyright (c) 1997, 1998, 1999, 2002, 2007, 2008 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
9  * NASA Ames Research Center, and by Luke Mewburn.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
30  * POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 /*
34  * Copyright (c) 1982, 1986, 1991, 1993
35  *	The Regents of the University of California.  All rights reserved.
36  * (c) UNIX System Laboratories, Inc.
37  * All or some portions of this file are derived from material licensed
38  * to the University of California by American Telephone and Telegraph
39  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
40  * the permission of UNIX System Laboratories, Inc.
41  *
42  * Copyright (c) 1992, 1993
43  *	The Regents of the University of California.  All rights reserved.
44  *
45  * This software was developed by the Computer Systems Engineering group
46  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
47  * contributed to Berkeley.
48  *
49  * All advertising materials mentioning features or use of this software
50  * must display the following acknowledgement:
51  *	This product includes software developed by the University of
52  *	California, Lawrence Berkeley Laboratory.
53  *
54  * Redistribution and use in source and binary forms, with or without
55  * modification, are permitted provided that the following conditions
56  * are met:
57  * 1. Redistributions of source code must retain the above copyright
58  *    notice, this list of conditions and the following disclaimer.
59  * 2. Redistributions in binary form must reproduce the above copyright
60  *    notice, this list of conditions and the following disclaimer in the
61  *    documentation and/or other materials provided with the distribution.
62  * 3. Neither the name of the University nor the names of its contributors
63  *    may be used to endorse or promote products derived from this software
64  *    without specific prior written permission.
65  *
66  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
67  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
68  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
69  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
70  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
71  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
72  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
73  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
74  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
75  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
76  * SUCH DAMAGE.
77  *
78  *	@(#)kern_subr.c	8.4 (Berkeley) 2/14/95
79  */
80 
81 #include <sys/cdefs.h>
82 __KERNEL_RCSID(0, "$NetBSD: kern_subr.c,v 1.220 2018/10/07 11:24:16 mlelstv Exp $");
83 
84 #include "opt_ddb.h"
85 #include "opt_md.h"
86 #include "opt_tftproot.h"
87 
88 #include <sys/param.h>
89 #include <sys/systm.h>
90 #include <sys/proc.h>
91 #include <sys/mount.h>
92 #include <sys/device.h>
93 #include <sys/reboot.h>
94 #include <sys/conf.h>
95 #include <sys/disk.h>
96 #include <sys/disklabel.h>
97 #include <sys/queue.h>
98 #include <sys/fcntl.h>
99 #include <sys/kauth.h>
100 #include <sys/stat.h>
101 #include <sys/vnode.h>
102 #include <sys/module.h>
103 
104 #include <dev/cons.h>
105 
106 #include <net/if.h>
107 
108 /* XXX these should eventually move to subr_autoconf.c */
109 static device_t finddevice(const char *);
110 static device_t getdisk(char *, int, int, dev_t *, int);
111 static device_t parsedisk(char *, int, int, dev_t *);
112 static const char *getwedgename(const char *, int);
113 
114 #ifdef TFTPROOT
115 int tftproot_dhcpboot(device_t);
116 #endif
117 
118 dev_t	dumpcdev;	/* for savecore */
119 
120 static int
121 isswap(device_t dv)
122 {
123 	struct dkwedge_info wi;
124 	struct vnode *vn;
125 	int error;
126 
127 	if (device_class(dv) != DV_DISK || !device_is_a(dv, "dk"))
128 		return 0;
129 
130 	if ((vn = opendisk(dv)) == NULL)
131 		return 0;
132 
133 	error = VOP_IOCTL(vn, DIOCGWEDGEINFO, &wi, FREAD, NOCRED);
134 	VOP_CLOSE(vn, FREAD, NOCRED);
135 	vput(vn);
136 	if (error) {
137 #ifdef DEBUG_WEDGE
138 		printf("%s: Get wedge info returned %d\n", device_xname(dv), error);
139 #endif
140 		return 0;
141 	}
142 	return strcmp(wi.dkw_ptype, DKW_PTYPE_SWAP) == 0;
143 }
144 
145 /*
146  * Determine the root device and, if instructed to, the root file system.
147  */
148 
149 #ifdef MEMORY_DISK_IS_ROOT
150 int md_is_root = 1;
151 #else
152 int md_is_root = 0;
153 #endif
154 
155 /*
156  * The device and partition that we booted from.
157  */
158 device_t booted_device;
159 const char *booted_method;
160 int booted_partition;
161 daddr_t booted_startblk;
162 uint64_t booted_nblks;
163 char *bootspec;
164 
165 /*
166  * Use partition letters if it's a disk class but not a wedge or flash.
167  * XXX Check for wedge/flash is kinda gross.
168  */
169 #define	DEV_USES_PARTITIONS(dv)						\
170 	(device_class((dv)) == DV_DISK &&				\
171 	 !device_is_a((dv), "dk") &&					\
172 	 !device_is_a((dv), "flash"))
173 
174 void
175 setroot(device_t bootdv, int bootpartition)
176 {
177 	device_t dv;
178 	deviter_t di;
179 	int len, majdev;
180 	dev_t nrootdev;
181 	dev_t ndumpdev = NODEV;
182 	char buf[128];
183 	const char *rootdevname;
184 	const char *dumpdevname;
185 	device_t rootdv = NULL;		/* XXX gcc -Wuninitialized */
186 	device_t dumpdv = NULL;
187 	struct ifnet *ifp;
188 	const char *deffsname;
189 	struct vfsops *vops;
190 
191 #ifdef TFTPROOT
192 	if (tftproot_dhcpboot(bootdv) != 0)
193 		boothowto |= RB_ASKNAME;
194 #endif
195 
196 	/*
197 	 * For root on md0 we have to force the attachment of md0.
198 	 */
199 	if (md_is_root) {
200 		int md_major;
201 		dev_t md_dev;
202 
203 		bootdv = NULL;
204 		md_major = devsw_name2blk("md", NULL, 0);
205 		if (md_major >= 0) {
206 			md_dev = MAKEDISKDEV(md_major, 0, RAW_PART);
207 			if (bdev_open(md_dev, FREAD, S_IFBLK, curlwp) == 0)
208 				bootdv = device_find_by_xname("md0");
209 		}
210 		if (bootdv == NULL)
211 			panic("Cannot open \"md0\" (root)");
212 	}
213 
214 	/*
215 	 * Let bootcode augment "rootspec".
216 	 */
217 	if (rootspec == NULL)
218 		rootspec = bootspec;
219 
220 	/*
221 	 * If NFS is specified as the file system, and we found
222 	 * a DV_DISK boot device (or no boot device at all), then
223 	 * find a reasonable network interface for "rootspec".
224 	 */
225 	vops = vfs_getopsbyname(MOUNT_NFS);
226 	if (vops != NULL && strcmp(rootfstype, MOUNT_NFS) == 0 &&
227 	    rootspec == NULL &&
228 	    (bootdv == NULL || device_class(bootdv) != DV_IFNET)) {
229 		int s = pserialize_read_enter();
230 		IFNET_READER_FOREACH(ifp) {
231 			if ((ifp->if_flags &
232 			     (IFF_LOOPBACK|IFF_POINTOPOINT)) == 0)
233 				break;
234 		}
235 		if (ifp == NULL) {
236 			/*
237 			 * Can't find a suitable interface; ask the
238 			 * user.
239 			 */
240 			boothowto |= RB_ASKNAME;
241 		} else {
242 			/*
243 			 * Have a suitable interface; behave as if
244 			 * the user specified this interface.
245 			 */
246 			rootspec = (const char *)ifp->if_xname;
247 		}
248 		pserialize_read_exit(s);
249 	}
250 	if (vops != NULL)
251 		vfs_delref(vops);
252 
253 	/*
254 	 * If wildcarded root and we the boot device wasn't determined,
255 	 * ask the user.
256 	 */
257 	if (rootspec == NULL && bootdv == NULL)
258 		boothowto |= RB_ASKNAME;
259 
260  top:
261 	if (boothowto & RB_ASKNAME) {
262 		device_t defdumpdv;
263 
264 		for (;;) {
265 			printf("root device");
266 			if (bootdv != NULL) {
267 				printf(" (default %s", device_xname(bootdv));
268 				if (DEV_USES_PARTITIONS(bootdv))
269 					printf("%c", bootpartition + 'a');
270 				printf(")");
271 			}
272 			printf(": ");
273 			len = cngetsn(buf, sizeof(buf));
274 			if (len == 0 && bootdv != NULL) {
275 				strlcpy(buf, device_xname(bootdv), sizeof(buf));
276 				len = strlen(buf);
277 			}
278 			if (len > 0 && buf[len - 1] == '*') {
279 				buf[--len] = '\0';
280 				dv = getdisk(buf, len, 1, &nrootdev, 0);
281 				if (dv != NULL) {
282 					rootdv = dv;
283 					break;
284 				}
285 			}
286 			dv = getdisk(buf, len, bootpartition, &nrootdev, 0);
287 			if (dv != NULL) {
288 				rootdv = dv;
289 				break;
290 			}
291 		}
292 
293 		/*
294 		 * Set up the default dump device.  If root is on
295 		 * a network device, there is no default dump
296 		 * device, since we don't support dumps to the
297 		 * network.
298 		 */
299 		if (DEV_USES_PARTITIONS(rootdv) == 0)
300 			defdumpdv = NULL;
301 		else
302 			defdumpdv = rootdv;
303 
304 		for (;;) {
305 			printf("dump device");
306 			if (defdumpdv != NULL) {
307 				/*
308 				 * Note, we know it's a disk if we get here.
309 				 */
310 				printf(" (default %sb)", device_xname(defdumpdv));
311 			}
312 			printf(": ");
313 			len = cngetsn(buf, sizeof(buf));
314 			if (len == 0) {
315 				if (defdumpdv != NULL) {
316 					ndumpdev = MAKEDISKDEV(major(nrootdev),
317 					    DISKUNIT(nrootdev), 1);
318 				}
319 				dumpdv = defdumpdv;
320 				break;
321 			}
322 			if (len == 4 && strcmp(buf, "none") == 0) {
323 				dumpdv = NULL;
324 				break;
325 			}
326 			dv = getdisk(buf, len, 1, &ndumpdev, 1);
327 			if (dv != NULL) {
328 				dumpdv = dv;
329 				break;
330 			}
331 		}
332 
333 		rootdev = nrootdev;
334 		dumpdev = ndumpdev;
335 
336 		for (vops = LIST_FIRST(&vfs_list); vops != NULL;
337 		     vops = LIST_NEXT(vops, vfs_list)) {
338 			if (vops->vfs_mountroot != NULL &&
339 			    strcmp(rootfstype, vops->vfs_name) == 0)
340 			break;
341 		}
342 
343 		if (vops == NULL) {
344 			deffsname = "generic";
345 		} else
346 			deffsname = vops->vfs_name;
347 
348 		for (;;) {
349 			printf("file system (default %s): ", deffsname);
350 			len = cngetsn(buf, sizeof(buf));
351 			if (len == 0) {
352 				if (strcmp(deffsname, "generic") == 0)
353 					rootfstype = ROOT_FSTYPE_ANY;
354 				break;
355 			}
356 			if (len == 4 && strcmp(buf, "halt") == 0)
357 				cpu_reboot(RB_HALT, NULL);
358 			else if (len == 6 && strcmp(buf, "reboot") == 0)
359 				cpu_reboot(0, NULL);
360 #if defined(DDB)
361 			else if (len == 3 && strcmp(buf, "ddb") == 0) {
362 				console_debugger();
363 			}
364 #endif
365 			else if (len == 7 && strcmp(buf, "generic") == 0) {
366 				rootfstype = ROOT_FSTYPE_ANY;
367 				break;
368 			}
369 			vops = vfs_getopsbyname(buf);
370 			if (vops == NULL || vops->vfs_mountroot == NULL) {
371 				printf("use one of: generic");
372 				for (vops = LIST_FIRST(&vfs_list);
373 				     vops != NULL;
374 				     vops = LIST_NEXT(vops, vfs_list)) {
375 					if (vops->vfs_mountroot != NULL)
376 						printf(" %s", vops->vfs_name);
377 				}
378 				if (vops != NULL)
379 					vfs_delref(vops);
380 #if defined(DDB)
381 				printf(" ddb");
382 #endif
383 				printf(" halt reboot\n");
384 			} else {
385 				/*
386 				 * XXX If *vops gets freed between here and
387 				 * the call to mountroot(), rootfstype will
388 				 * point to something unexpected.  But in
389 				 * this case the system will fail anyway.
390 				 */
391 				rootfstype = vops->vfs_name;
392 				vfs_delref(vops);
393 				break;
394 			}
395 		}
396 
397 	} else if (rootspec == NULL) {
398 		/*
399 		 * Wildcarded root; use the boot device.
400 		 */
401 		rootdv = bootdv;
402 
403 		if (bootdv)
404 			majdev = devsw_name2blk(device_xname(bootdv), NULL, 0);
405 		else
406 			majdev = -1;
407 		if (majdev >= 0) {
408 			/*
409 			 * Root is on a disk.  `bootpartition' is root,
410 			 * unless the device does not use partitions.
411 			 */
412 			if (DEV_USES_PARTITIONS(bootdv))
413 				rootdev = MAKEDISKDEV(majdev,
414 						      device_unit(bootdv),
415 						      bootpartition);
416 			else
417 				rootdev = makedev(majdev, device_unit(bootdv));
418 		}
419 	} else {
420 
421 		/*
422 		 * `root on <dev> ...'
423 		 */
424 
425 		/*
426 		 * If it's a network interface, we can bail out
427 		 * early.
428 		 */
429 		dv = finddevice(rootspec);
430 		if (dv != NULL && device_class(dv) == DV_IFNET) {
431 			rootdv = dv;
432 			goto haveroot;
433 		}
434 
435 		if (dv != NULL && device_class(dv) == DV_DISK &&
436 		    !DEV_USES_PARTITIONS(dv) &&
437 		    (majdev = devsw_name2blk(device_xname(dv), NULL, 0)) >= 0) {
438 			rootdv = dv;
439 			rootdev = makedev(majdev, device_unit(dv));
440 			goto haveroot;
441 		}
442 
443 		rootdevname = devsw_blk2name(major(rootdev));
444 		if (rootdevname == NULL) {
445 			printf("unknown device major 0x%llx\n",
446 			    (unsigned long long)rootdev);
447 			boothowto |= RB_ASKNAME;
448 			goto top;
449 		}
450 		memset(buf, 0, sizeof(buf));
451 		snprintf(buf, sizeof(buf), "%s%llu", rootdevname,
452 		    (unsigned long long)DISKUNIT(rootdev));
453 
454 		rootdv = finddevice(buf);
455 		if (rootdv == NULL) {
456 			printf("device %s (0x%llx) not configured\n",
457 			    buf, (unsigned long long)rootdev);
458 			boothowto |= RB_ASKNAME;
459 			goto top;
460 		}
461 	}
462 
463  haveroot:
464 
465 	root_device = rootdv;
466 
467 	switch (device_class(rootdv)) {
468 	case DV_IFNET:
469 	case DV_DISK:
470 		aprint_normal("root on %s", device_xname(rootdv));
471 		if (DEV_USES_PARTITIONS(rootdv))
472 			aprint_normal("%c", (int)DISKPART(rootdev) + 'a');
473 		break;
474 
475 	default:
476 		printf("can't determine root device\n");
477 		boothowto |= RB_ASKNAME;
478 		goto top;
479 	}
480 
481 	/*
482 	 * Now configure the dump device.
483 	 *
484 	 * If we haven't figured out the dump device, do so, with
485 	 * the following rules:
486 	 *
487 	 *	(a) We already know dumpdv in the RB_ASKNAME case.
488 	 *
489 	 *	(b) If dumpspec is set, try to use it.  If the device
490 	 *	    is not available, punt.
491 	 *
492 	 *	(c) If dumpspec is not set, the dump device is
493 	 *	    wildcarded or unspecified.  If the root device
494 	 *	    is DV_IFNET, punt.  Otherwise, use partition b
495 	 *	    of the root device.
496 	 */
497 
498 	if (boothowto & RB_ASKNAME) {		/* (a) */
499 		if (dumpdv == NULL)
500 			goto nodumpdev;
501 	} else if (dumpspec != NULL) {		/* (b) */
502 		if (strcmp(dumpspec, "none") == 0 || dumpdev == NODEV) {
503 			/*
504 			 * Operator doesn't want a dump device.
505 			 * Or looks like they tried to pick a network
506 			 * device.  Oops.
507 			 */
508 			goto nodumpdev;
509 		}
510 
511 		dumpdevname = devsw_blk2name(major(dumpdev));
512 		if (dumpdevname == NULL)
513 			goto nodumpdev;
514 		memset(buf, 0, sizeof(buf));
515 		snprintf(buf, sizeof(buf), "%s%llu", dumpdevname,
516 		    (unsigned long long)DISKUNIT(dumpdev));
517 
518 		dumpdv = finddevice(buf);
519 		if (dumpdv == NULL) {
520 			/*
521 			 * Device not configured.
522 			 */
523 			goto nodumpdev;
524 		}
525 	} else {				/* (c) */
526 		if (DEV_USES_PARTITIONS(rootdv) == 0) {
527 			for (dv = deviter_first(&di, DEVITER_F_ROOT_FIRST);
528 			     dv != NULL;
529 			     dv = deviter_next(&di))
530 				if (isswap(dv))
531 					break;
532 			deviter_release(&di);
533 			if (dv == NULL)
534 				goto nodumpdev;
535 
536 			majdev = devsw_name2blk(device_xname(dv), NULL, 0);
537 			if (majdev < 0)
538 				goto nodumpdev;
539 			dumpdv = dv;
540 			dumpdev = makedev(majdev, device_unit(dumpdv));
541 		} else {
542 			dumpdv = rootdv;
543 			dumpdev = MAKEDISKDEV(major(rootdev),
544 			    device_unit(dumpdv), 1);
545 		}
546 	}
547 
548 	dumpcdev = devsw_blk2chr(dumpdev);
549 	aprint_normal(" dumps on %s", device_xname(dumpdv));
550 	if (DEV_USES_PARTITIONS(dumpdv))
551 		aprint_normal("%c", (int)DISKPART(dumpdev) + 'a');
552 	aprint_normal("\n");
553 	return;
554 
555  nodumpdev:
556 	dumpdev = NODEV;
557 	dumpcdev = NODEV;
558 	aprint_normal("\n");
559 }
560 
561 static device_t
562 finddevice(const char *name)
563 {
564 	const char *wname;
565 
566 	if ((wname = getwedgename(name, strlen(name))) != NULL)
567 		return dkwedge_find_by_wname(wname);
568 
569 	return device_find_by_xname(name);
570 }
571 
572 static device_t
573 getdisk(char *str, int len, int defpart, dev_t *devp, int isdump)
574 {
575 	device_t dv;
576 	deviter_t di;
577 
578 	if ((dv = parsedisk(str, len, defpart, devp)) == NULL) {
579 		printf("use one of:");
580 		for (dv = deviter_first(&di, DEVITER_F_ROOT_FIRST); dv != NULL;
581 		     dv = deviter_next(&di)) {
582 			if (DEV_USES_PARTITIONS(dv))
583 				printf(" %s[a-%c]", device_xname(dv),
584 				    'a' + MAXPARTITIONS - 1);
585 			else if (device_class(dv) == DV_DISK)
586 				printf(" %s", device_xname(dv));
587 			if (isdump == 0 && device_class(dv) == DV_IFNET)
588 				printf(" %s", device_xname(dv));
589 		}
590 		deviter_release(&di);
591 		dkwedge_print_wnames();
592 		if (isdump)
593 			printf(" none");
594 #if defined(DDB)
595 		printf(" ddb");
596 #endif
597 		printf(" halt reboot\n");
598 	}
599 	return dv;
600 }
601 
602 static const char *
603 getwedgename(const char *name, int namelen)
604 {
605 	const char *wpfx = "wedge:";
606 	const int wpfxlen = strlen(wpfx);
607 
608 	if (namelen < wpfxlen || strncmp(name, wpfx, wpfxlen) != 0)
609 		return NULL;
610 
611 	return name + wpfxlen;
612 }
613 
614 static device_t
615 parsedisk(char *str, int len, int defpart, dev_t *devp)
616 {
617 	device_t dv;
618 	const char *wname;
619 	char *cp, c;
620 	int majdev, part;
621 	if (len == 0)
622 		return (NULL);
623 
624 	if (len == 4 && strcmp(str, "halt") == 0)
625 		cpu_reboot(RB_HALT, NULL);
626 	else if (len == 6 && strcmp(str, "reboot") == 0)
627 		cpu_reboot(0, NULL);
628 #if defined(DDB)
629 	else if (len == 3 && strcmp(str, "ddb") == 0)
630 		console_debugger();
631 #endif
632 
633 	cp = str + len - 1;
634 	c = *cp;
635 
636 	if ((wname = getwedgename(str, len)) != NULL) {
637 		if ((dv = dkwedge_find_by_wname(wname)) == NULL)
638 			return NULL;
639 		part = defpart;
640 		goto gotdisk;
641 	} else if (c >= 'a' && c <= ('a' + MAXPARTITIONS - 1)) {
642 		part = c - 'a';
643 		*cp = '\0';
644 	} else
645 		part = defpart;
646 
647 	dv = finddevice(str);
648 	if (dv != NULL) {
649 		if (device_class(dv) == DV_DISK) {
650  gotdisk:
651 			majdev = devsw_name2blk(device_xname(dv), NULL, 0);
652 			if (majdev < 0)
653 				panic("parsedisk");
654 			if (DEV_USES_PARTITIONS(dv))
655 				*devp = MAKEDISKDEV(majdev, device_unit(dv),
656 						    part);
657 			else
658 				*devp = makedev(majdev, device_unit(dv));
659 		}
660 
661 		if (device_class(dv) == DV_IFNET)
662 			*devp = NODEV;
663 	}
664 
665 	*cp = c;
666 	return (dv);
667 }
668