xref: /netbsd-src/sys/kern/kern_subr.c (revision 6a493d6bc668897c91594964a732d38505b70cbb)
1 /*	$NetBSD: kern_subr.c,v 1.214 2013/12/09 16:49:43 pooka 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 1.214 2013/12/09 16:49:43 pooka 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 int booted_partition;
160 daddr_t booted_startblk;
161 uint64_t booted_nblks;
162 
163 /*
164  * Use partition letters if it's a disk class but not a wedge.
165  * XXX Check for wedge is kinda gross.
166  */
167 #define	DEV_USES_PARTITIONS(dv)						\
168 	(device_class((dv)) == DV_DISK &&				\
169 	 !device_is_a((dv), "dk"))
170 
171 void
172 setroot(device_t bootdv, int bootpartition)
173 {
174 	device_t dv;
175 	deviter_t di;
176 	int len, majdev;
177 	dev_t nrootdev;
178 	dev_t ndumpdev = NODEV;
179 	char buf[128];
180 	const char *rootdevname;
181 	const char *dumpdevname;
182 	device_t rootdv = NULL;		/* XXX gcc -Wuninitialized */
183 	device_t dumpdv = NULL;
184 	struct ifnet *ifp;
185 	const char *deffsname;
186 	struct vfsops *vops;
187 
188 #ifdef TFTPROOT
189 	if (tftproot_dhcpboot(bootdv) != 0)
190 		boothowto |= RB_ASKNAME;
191 #endif
192 
193 	/*
194 	 * For root on md0 we have to force the attachment of md0.
195 	 */
196 	if (md_is_root) {
197 		int md_major;
198 		dev_t md_dev;
199 
200 		bootdv = NULL;
201 		md_major = devsw_name2blk("md", NULL, 0);
202 		if (md_major >= 0) {
203 			md_dev = MAKEDISKDEV(md_major, 0, RAW_PART);
204 			if (bdev_open(md_dev, FREAD, S_IFBLK, curlwp) == 0)
205 				bootdv = device_find_by_xname("md0");
206 		}
207 		if (bootdv == NULL)
208 			panic("Cannot open \"md0\" (root)");
209 	}
210 
211 	/*
212 	 * If NFS is specified as the file system, and we found
213 	 * a DV_DISK boot device (or no boot device at all), then
214 	 * find a reasonable network interface for "rootspec".
215 	 */
216 	vops = vfs_getopsbyname(MOUNT_NFS);
217 	if (vops != NULL && strcmp(rootfstype, MOUNT_NFS) == 0 &&
218 	    rootspec == NULL &&
219 	    (bootdv == NULL || device_class(bootdv) != DV_IFNET)) {
220 		IFNET_FOREACH(ifp) {
221 			if ((ifp->if_flags &
222 			     (IFF_LOOPBACK|IFF_POINTOPOINT)) == 0)
223 				break;
224 		}
225 		if (ifp == NULL) {
226 			/*
227 			 * Can't find a suitable interface; ask the
228 			 * user.
229 			 */
230 			boothowto |= RB_ASKNAME;
231 		} else {
232 			/*
233 			 * Have a suitable interface; behave as if
234 			 * the user specified this interface.
235 			 */
236 			rootspec = (const char *)ifp->if_xname;
237 		}
238 	}
239 	if (vops != NULL)
240 		vfs_delref(vops);
241 
242 	/*
243 	 * If wildcarded root and we the boot device wasn't determined,
244 	 * ask the user.
245 	 */
246 	if (rootspec == NULL && bootdv == NULL)
247 		boothowto |= RB_ASKNAME;
248 
249  top:
250 	if (boothowto & RB_ASKNAME) {
251 		device_t defdumpdv;
252 
253 		for (;;) {
254 			printf("root device");
255 			if (bootdv != NULL) {
256 				printf(" (default %s", device_xname(bootdv));
257 				if (DEV_USES_PARTITIONS(bootdv))
258 					printf("%c", bootpartition + 'a');
259 				printf(")");
260 			}
261 			printf(": ");
262 			len = cngetsn(buf, sizeof(buf));
263 			if (len == 0 && bootdv != NULL) {
264 				strlcpy(buf, device_xname(bootdv), sizeof(buf));
265 				len = strlen(buf);
266 			}
267 			if (len > 0 && buf[len - 1] == '*') {
268 				buf[--len] = '\0';
269 				dv = getdisk(buf, len, 1, &nrootdev, 0);
270 				if (dv != NULL) {
271 					rootdv = dv;
272 					break;
273 				}
274 			}
275 			dv = getdisk(buf, len, bootpartition, &nrootdev, 0);
276 			if (dv != NULL) {
277 				rootdv = dv;
278 				break;
279 			}
280 		}
281 
282 		/*
283 		 * Set up the default dump device.  If root is on
284 		 * a network device, there is no default dump
285 		 * device, since we don't support dumps to the
286 		 * network.
287 		 */
288 		if (DEV_USES_PARTITIONS(rootdv) == 0)
289 			defdumpdv = NULL;
290 		else
291 			defdumpdv = rootdv;
292 
293 		for (;;) {
294 			printf("dump device");
295 			if (defdumpdv != NULL) {
296 				/*
297 				 * Note, we know it's a disk if we get here.
298 				 */
299 				printf(" (default %sb)", device_xname(defdumpdv));
300 			}
301 			printf(": ");
302 			len = cngetsn(buf, sizeof(buf));
303 			if (len == 0) {
304 				if (defdumpdv != NULL) {
305 					ndumpdev = MAKEDISKDEV(major(nrootdev),
306 					    DISKUNIT(nrootdev), 1);
307 				}
308 				dumpdv = defdumpdv;
309 				break;
310 			}
311 			if (len == 4 && strcmp(buf, "none") == 0) {
312 				dumpdv = NULL;
313 				break;
314 			}
315 			dv = getdisk(buf, len, 1, &ndumpdev, 1);
316 			if (dv != NULL) {
317 				dumpdv = dv;
318 				break;
319 			}
320 		}
321 
322 		rootdev = nrootdev;
323 		dumpdev = ndumpdev;
324 
325 		for (vops = LIST_FIRST(&vfs_list); vops != NULL;
326 		     vops = LIST_NEXT(vops, vfs_list)) {
327 			if (vops->vfs_mountroot != NULL &&
328 			    strcmp(rootfstype, vops->vfs_name) == 0)
329 			break;
330 		}
331 
332 		if (vops == NULL) {
333 			deffsname = "generic";
334 		} else
335 			deffsname = vops->vfs_name;
336 
337 		for (;;) {
338 			printf("file system (default %s): ", deffsname);
339 			len = cngetsn(buf, sizeof(buf));
340 			if (len == 0) {
341 				if (strcmp(deffsname, "generic") == 0)
342 					rootfstype = ROOT_FSTYPE_ANY;
343 				break;
344 			}
345 			if (len == 4 && strcmp(buf, "halt") == 0)
346 				cpu_reboot(RB_HALT, NULL);
347 			else if (len == 6 && strcmp(buf, "reboot") == 0)
348 				cpu_reboot(0, NULL);
349 #if defined(DDB)
350 			else if (len == 3 && strcmp(buf, "ddb") == 0) {
351 				console_debugger();
352 			}
353 #endif
354 			else if (len == 7 && strcmp(buf, "generic") == 0) {
355 				rootfstype = ROOT_FSTYPE_ANY;
356 				break;
357 			}
358 			vops = vfs_getopsbyname(buf);
359 			if (vops == NULL || vops->vfs_mountroot == NULL) {
360 				printf("use one of: generic");
361 				for (vops = LIST_FIRST(&vfs_list);
362 				     vops != NULL;
363 				     vops = LIST_NEXT(vops, vfs_list)) {
364 					if (vops->vfs_mountroot != NULL)
365 						printf(" %s", vops->vfs_name);
366 				}
367 				if (vops != NULL)
368 					vfs_delref(vops);
369 #if defined(DDB)
370 				printf(" ddb");
371 #endif
372 				printf(" halt reboot\n");
373 			} else {
374 				/*
375 				 * XXX If *vops gets freed between here and
376 				 * the call to mountroot(), rootfstype will
377 				 * point to something unexpected.  But in
378 				 * this case the system will fail anyway.
379 				 */
380 				rootfstype = vops->vfs_name;
381 				vfs_delref(vops);
382 				break;
383 			}
384 		}
385 
386 	} else if (rootspec == NULL) {
387 		/*
388 		 * Wildcarded root; use the boot device.
389 		 */
390 		rootdv = bootdv;
391 
392 		if (bootdv)
393 			majdev = devsw_name2blk(device_xname(bootdv), NULL, 0);
394 		else
395 			majdev = -1;
396 		if (majdev >= 0) {
397 			/*
398 			 * Root is on a disk.  `bootpartition' is root,
399 			 * unless the device does not use partitions.
400 			 */
401 			if (DEV_USES_PARTITIONS(bootdv))
402 				rootdev = MAKEDISKDEV(majdev,
403 						      device_unit(bootdv),
404 						      bootpartition);
405 			else
406 				rootdev = makedev(majdev, device_unit(bootdv));
407 		}
408 	} else {
409 
410 		/*
411 		 * `root on <dev> ...'
412 		 */
413 
414 		/*
415 		 * If it's a network interface, we can bail out
416 		 * early.
417 		 */
418 		dv = finddevice(rootspec);
419 		if (dv != NULL && device_class(dv) == DV_IFNET) {
420 			rootdv = dv;
421 			goto haveroot;
422 		}
423 
424 		if (rootdev == NODEV &&
425 		    device_class(dv) == DV_DISK && device_is_a(dv, "dk") &&
426 		    (majdev = devsw_name2blk(device_xname(dv), NULL, 0)) >= 0)
427 			rootdev = makedev(majdev, device_unit(dv));
428 
429 		rootdevname = devsw_blk2name(major(rootdev));
430 		if (rootdevname == NULL) {
431 			printf("unknown device major 0x%llx\n",
432 			    (unsigned long long)rootdev);
433 			boothowto |= RB_ASKNAME;
434 			goto top;
435 		}
436 		memset(buf, 0, sizeof(buf));
437 		snprintf(buf, sizeof(buf), "%s%llu", rootdevname,
438 		    (unsigned long long)DISKUNIT(rootdev));
439 
440 		rootdv = finddevice(buf);
441 		if (rootdv == NULL) {
442 			printf("device %s (0x%llx) not configured\n",
443 			    buf, (unsigned long long)rootdev);
444 			boothowto |= RB_ASKNAME;
445 			goto top;
446 		}
447 	}
448 
449  haveroot:
450 
451 	root_device = rootdv;
452 
453 	switch (device_class(rootdv)) {
454 	case DV_IFNET:
455 	case DV_DISK:
456 		aprint_normal("root on %s", device_xname(rootdv));
457 		if (DEV_USES_PARTITIONS(rootdv))
458 			aprint_normal("%c", (int)DISKPART(rootdev) + 'a');
459 		break;
460 
461 	default:
462 		printf("can't determine root device\n");
463 		boothowto |= RB_ASKNAME;
464 		goto top;
465 	}
466 
467 	/*
468 	 * Now configure the dump device.
469 	 *
470 	 * If we haven't figured out the dump device, do so, with
471 	 * the following rules:
472 	 *
473 	 *	(a) We already know dumpdv in the RB_ASKNAME case.
474 	 *
475 	 *	(b) If dumpspec is set, try to use it.  If the device
476 	 *	    is not available, punt.
477 	 *
478 	 *	(c) If dumpspec is not set, the dump device is
479 	 *	    wildcarded or unspecified.  If the root device
480 	 *	    is DV_IFNET, punt.  Otherwise, use partition b
481 	 *	    of the root device.
482 	 */
483 
484 	if (boothowto & RB_ASKNAME) {		/* (a) */
485 		if (dumpdv == NULL)
486 			goto nodumpdev;
487 	} else if (dumpspec != NULL) {		/* (b) */
488 		if (strcmp(dumpspec, "none") == 0 || dumpdev == NODEV) {
489 			/*
490 			 * Operator doesn't want a dump device.
491 			 * Or looks like they tried to pick a network
492 			 * device.  Oops.
493 			 */
494 			goto nodumpdev;
495 		}
496 
497 		dumpdevname = devsw_blk2name(major(dumpdev));
498 		if (dumpdevname == NULL)
499 			goto nodumpdev;
500 		memset(buf, 0, sizeof(buf));
501 		snprintf(buf, sizeof(buf), "%s%llu", dumpdevname,
502 		    (unsigned long long)DISKUNIT(dumpdev));
503 
504 		dumpdv = finddevice(buf);
505 		if (dumpdv == NULL) {
506 			/*
507 			 * Device not configured.
508 			 */
509 			goto nodumpdev;
510 		}
511 	} else {				/* (c) */
512 		if (DEV_USES_PARTITIONS(rootdv) == 0) {
513 			for (dv = deviter_first(&di, DEVITER_F_ROOT_FIRST);
514 			     dv != NULL;
515 			     dv = deviter_next(&di))
516 				if (isswap(dv))
517 					break;
518 			deviter_release(&di);
519 			if (dv == NULL)
520 				goto nodumpdev;
521 
522 			majdev = devsw_name2blk(device_xname(dv), NULL, 0);
523 			if (majdev < 0)
524 				goto nodumpdev;
525 			dumpdv = dv;
526 			dumpdev = makedev(majdev, device_unit(dumpdv));
527 		} else {
528 			dumpdv = rootdv;
529 			dumpdev = MAKEDISKDEV(major(rootdev),
530 			    device_unit(dumpdv), 1);
531 		}
532 	}
533 
534 	dumpcdev = devsw_blk2chr(dumpdev);
535 	aprint_normal(" dumps on %s", device_xname(dumpdv));
536 	if (DEV_USES_PARTITIONS(dumpdv))
537 		aprint_normal("%c", (int)DISKPART(dumpdev) + 'a');
538 	aprint_normal("\n");
539 	return;
540 
541  nodumpdev:
542 	dumpdev = NODEV;
543 	dumpcdev = NODEV;
544 	aprint_normal("\n");
545 }
546 
547 static device_t
548 finddevice(const char *name)
549 {
550 	const char *wname;
551 
552 	if ((wname = getwedgename(name, strlen(name))) != NULL)
553 		return dkwedge_find_by_wname(wname);
554 
555 	return device_find_by_xname(name);
556 }
557 
558 static device_t
559 getdisk(char *str, int len, int defpart, dev_t *devp, int isdump)
560 {
561 	device_t dv;
562 	deviter_t di;
563 
564 	if ((dv = parsedisk(str, len, defpart, devp)) == NULL) {
565 		printf("use one of:");
566 		for (dv = deviter_first(&di, DEVITER_F_ROOT_FIRST); dv != NULL;
567 		     dv = deviter_next(&di)) {
568 			if (DEV_USES_PARTITIONS(dv))
569 				printf(" %s[a-%c]", device_xname(dv),
570 				    'a' + MAXPARTITIONS - 1);
571 			else if (device_class(dv) == DV_DISK)
572 				printf(" %s", device_xname(dv));
573 			if (isdump == 0 && device_class(dv) == DV_IFNET)
574 				printf(" %s", device_xname(dv));
575 		}
576 		deviter_release(&di);
577 		dkwedge_print_wnames();
578 		if (isdump)
579 			printf(" none");
580 #if defined(DDB)
581 		printf(" ddb");
582 #endif
583 		printf(" halt reboot\n");
584 	}
585 	return dv;
586 }
587 
588 static const char *
589 getwedgename(const char *name, int namelen)
590 {
591 	const char *wpfx = "wedge:";
592 	const int wpfxlen = strlen(wpfx);
593 
594 	if (namelen < wpfxlen || strncmp(name, wpfx, wpfxlen) != 0)
595 		return NULL;
596 
597 	return name + wpfxlen;
598 }
599 
600 static device_t
601 parsedisk(char *str, int len, int defpart, dev_t *devp)
602 {
603 	device_t dv;
604 	const char *wname;
605 	char *cp, c;
606 	int majdev, part;
607 	if (len == 0)
608 		return (NULL);
609 
610 	if (len == 4 && strcmp(str, "halt") == 0)
611 		cpu_reboot(RB_HALT, NULL);
612 	else if (len == 6 && strcmp(str, "reboot") == 0)
613 		cpu_reboot(0, NULL);
614 #if defined(DDB)
615 	else if (len == 3 && strcmp(str, "ddb") == 0)
616 		console_debugger();
617 #endif
618 
619 	cp = str + len - 1;
620 	c = *cp;
621 
622 	if ((wname = getwedgename(str, len)) != NULL) {
623 		if ((dv = dkwedge_find_by_wname(wname)) == NULL)
624 			return NULL;
625 		part = defpart;
626 		goto gotdisk;
627 	} else if (c >= 'a' && c <= ('a' + MAXPARTITIONS - 1)) {
628 		part = c - 'a';
629 		*cp = '\0';
630 	} else
631 		part = defpart;
632 
633 	dv = finddevice(str);
634 	if (dv != NULL) {
635 		if (device_class(dv) == DV_DISK) {
636  gotdisk:
637 			majdev = devsw_name2blk(device_xname(dv), NULL, 0);
638 			if (majdev < 0)
639 				panic("parsedisk");
640 			if (DEV_USES_PARTITIONS(dv))
641 				*devp = MAKEDISKDEV(majdev, device_unit(dv),
642 						    part);
643 			else
644 				*devp = makedev(majdev, device_unit(dv));
645 		}
646 
647 		if (device_class(dv) == DV_IFNET)
648 			*devp = NODEV;
649 	}
650 
651 	*cp = c;
652 	return (dv);
653 }
654