xref: /freebsd/sys/kern/kern_cons.c (revision 7899f917b1c0ea178f1d2be0cfb452086d079d23)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1988 University of Utah.
5  * Copyright (c) 1991 The Regents of the University of California.
6  * Copyright (c) 1999 Michael Smith
7  * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
8  *
9  * All rights reserved.
10  *
11  * This code is derived from software contributed to Berkeley by
12  * the Systems Programming Group of the University of Utah Computer
13  * Science Department.
14  *
15  * Redistribution and use in source and binary forms, with or without
16  * modification, are permitted provided that the following conditions
17  * are met:
18  * 1. Redistributions of source code must retain the above copyright
19  *    notice, this list of conditions and the following disclaimer.
20  * 2. Redistributions in binary form must reproduce the above copyright
21  *    notice, this list of conditions and the following disclaimer in the
22  *    documentation and/or other materials provided with the distribution.
23  * 3. Neither the name of the University nor the names of its contributors
24  *    may be used to endorse or promote products derived from this software
25  *    without specific prior written permission.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37  * SUCH DAMAGE.
38  */
39 
40 #include <sys/cdefs.h>
41 #include "opt_ddb.h"
42 #include "opt_syscons.h"
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/lock.h>
47 #include <sys/mutex.h>
48 #include <sys/conf.h>
49 #include <sys/cons.h>
50 #include <sys/fcntl.h>
51 #include <sys/kbio.h>
52 #include <sys/kdb.h>
53 #include <sys/kernel.h>
54 #include <sys/malloc.h>
55 #include <sys/msgbuf.h>
56 #include <sys/namei.h>
57 #include <sys/priv.h>
58 #include <sys/proc.h>
59 #include <sys/queue.h>
60 #include <sys/reboot.h>
61 #include <sys/sysctl.h>
62 #include <sys/sbuf.h>
63 #include <sys/tslog.h>
64 #include <sys/tty.h>
65 #include <sys/uio.h>
66 #include <sys/vnode.h>
67 
68 #include <ddb/ddb.h>
69 
70 #include <dev/kbd/kbdreg.h>
71 
72 #include <machine/cpu.h>
73 #include <machine/clock.h>
74 
75 /*
76  * Check for 'options EARLY_PRINTF' that may have been used in old kernel
77  * config files. If you are hitting this error you should update your
78  * config to use 'options EARLY_PRINTF=<device name>', e.g. with the
79  * Arm pl011 use:
80  *
81  * options EARLY_PRINTF=pl011
82  */
83 #if CHECK_EARLY_PRINTF(1)
84 #error Update your config to use 'options EARLY_PRINTF=<device name>'
85 #endif
86 
87 static MALLOC_DEFINE(M_TTYCONS, "tty console", "tty console handling");
88 
89 struct cn_device {
90 	STAILQ_ENTRY(cn_device) cnd_next;
91 	struct		consdev *cnd_cn;
92 };
93 
94 #define CNDEVPATHMAX	32
95 #define CNDEVTAB_SIZE	4
96 static struct cn_device cn_devtab[CNDEVTAB_SIZE];
97 static STAILQ_HEAD(, cn_device) cn_devlist =
98     STAILQ_HEAD_INITIALIZER(cn_devlist);
99 
100 int	cons_avail_mask = 0;	/* Bit mask. Each registered low level console
101 				 * which is currently unavailable for inpit
102 				 * (i.e., if it is in graphics mode) will have
103 				 * this bit cleared.
104 				 */
105 
106 int cn_mute;
107 SYSCTL_INT(_kern, OID_AUTO, consmute, CTLFLAG_RW, &cn_mute, 0,
108     "State of the console muting");
109 
110 static char *consbuf;			/* buffer used by `consmsgbuf' */
111 static struct callout conscallout;	/* callout for outputting to constty */
112 struct msgbuf consmsgbuf;		/* message buffer for console tty */
113 static bool console_pausing;		/* pause after each line during probe */
114 static const char console_pausestr[] =
115 "<pause; press any key to proceed to next line or '.' to end pause mode>";
116 struct tty *constty;			/* pointer to console "window" tty */
117 static struct mtx constty_mtx;		/* Mutex for constty assignment. */
118 MTX_SYSINIT(constty_mtx, &constty_mtx, "constty_mtx", MTX_DEF);
119 static struct mtx cnputs_mtx;		/* Mutex for cnputs(). */
120 MTX_SYSINIT(cnputs_mtx, &cnputs_mtx, "cnputs_mtx", MTX_SPIN | MTX_NOWITNESS);
121 
122 static void constty_timeout(void *arg);
123 
124 static struct consdev cons_consdev;
125 DATA_SET(cons_set, cons_consdev);
126 SET_DECLARE(cons_set, struct consdev);
127 
128 /*
129  * Stub for configurations that don't actually have a keyboard driver. Inclusion
130  * of kbd.c is contingent on any number of keyboard/console drivers being
131  * present in the kernel; rather than trying to catch them all, we'll just
132  * maintain this weak kbdinit that will be overridden by the strong version in
133  * kbd.c if it's present.
134  */
135 __weak_symbol void
136 kbdinit(void)
137 {
138 
139 }
140 
141 static void
142 mute_console(void *data __unused)
143 {
144 
145 	if ((boothowto & (RB_MUTEMSGS | RB_VERBOSE)) == RB_MUTEMSGS) {
146 		printf("-- Muting boot messages --\n");
147 		cn_mute = 1;
148 	}
149 }
150 
151 SYSINIT(mute_console, SI_SUB_COPYRIGHT, SI_ORDER_ANY, mute_console, NULL);
152 
153 void
154 cninit(void)
155 {
156 	struct consdev *best_cn, *cn, **list;
157 
158 	TSENTER();
159 	/*
160 	 * Check if we should mute the console (for security reasons perhaps)
161 	 * It can be changes dynamically using sysctl kern.consmute
162 	 * once we are up and going.
163 	 *
164 	 */
165         cn_mute = ((boothowto & (RB_MUTE
166 			|RB_SINGLE
167 			|RB_VERBOSE
168 			|RB_ASKNAME)) == RB_MUTE);
169 
170 	/*
171 	 * Bring up the kbd layer just in time for cnprobe.  Console drivers
172 	 * have a dependency on kbd being ready, so this fits nicely between the
173 	 * machdep callers of cninit() and MI probing/initialization of consoles
174 	 * here.
175 	 */
176 	kbdinit();
177 
178 	/*
179 	 * Find the first console with the highest priority.
180 	 */
181 	best_cn = NULL;
182 	SET_FOREACH(list, cons_set) {
183 		cn = *list;
184 		cnremove(cn);
185 		/* Skip cons_consdev. */
186 		if (cn->cn_ops == NULL)
187 			continue;
188 		cn->cn_ops->cn_probe(cn);
189 		if (cn->cn_pri == CN_DEAD)
190 			continue;
191 		if (best_cn == NULL || cn->cn_pri > best_cn->cn_pri)
192 			best_cn = cn;
193 		if (boothowto & RB_MULTIPLE) {
194 			/*
195 			 * Initialize console, and attach to it.
196 			 */
197 			cn->cn_ops->cn_init(cn);
198 			cnadd(cn);
199 		}
200 	}
201 	if (best_cn == NULL)
202 		return;
203 	if ((boothowto & RB_MULTIPLE) == 0) {
204 		best_cn->cn_ops->cn_init(best_cn);
205 		cnadd(best_cn);
206 	}
207 	if (boothowto & RB_PAUSE)
208 		console_pausing = true;
209 	/*
210 	 * Make the best console the preferred console.
211 	 */
212 	cnselect(best_cn);
213 
214 #ifdef EARLY_PRINTF
215 	/*
216 	 * Release early console.
217 	 */
218 	early_putc = NULL;
219 #endif
220 	TSEXIT();
221 }
222 
223 void
224 cninit_finish(void)
225 {
226 	console_pausing = false;
227 }
228 
229 /* add a new physical console to back the virtual console */
230 int
231 cnadd(struct consdev *cn)
232 {
233 	struct cn_device *cnd;
234 	int i;
235 
236 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next)
237 		if (cnd->cnd_cn == cn)
238 			return (0);
239 	for (i = 0; i < CNDEVTAB_SIZE; i++) {
240 		cnd = &cn_devtab[i];
241 		if (cnd->cnd_cn == NULL)
242 			break;
243 	}
244 	if (cnd->cnd_cn != NULL)
245 		return (ENOMEM);
246 	cnd->cnd_cn = cn;
247 	if (cn->cn_name[0] == '\0') {
248 		/* XXX: it is unclear if/where this print might output */
249 		printf("WARNING: console at %p has no name\n", cn);
250 	}
251 	STAILQ_INSERT_TAIL(&cn_devlist, cnd, cnd_next);
252 	if (STAILQ_FIRST(&cn_devlist) == cnd)
253 		ttyconsdev_select(cnd->cnd_cn->cn_name);
254 
255 	/* Add device to the active mask. */
256 	cnavailable(cn, (cn->cn_flags & CN_FLAG_NOAVAIL) == 0);
257 
258 	return (0);
259 }
260 
261 void
262 cnremove(struct consdev *cn)
263 {
264 	struct cn_device *cnd;
265 	int i;
266 
267 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
268 		if (cnd->cnd_cn != cn)
269 			continue;
270 		if (STAILQ_FIRST(&cn_devlist) == cnd)
271 			ttyconsdev_select(NULL);
272 		STAILQ_REMOVE(&cn_devlist, cnd, cn_device, cnd_next);
273 		cnd->cnd_cn = NULL;
274 
275 		/* Remove this device from available mask. */
276 		for (i = 0; i < CNDEVTAB_SIZE; i++)
277 			if (cnd == &cn_devtab[i]) {
278 				cons_avail_mask &= ~(1 << i);
279 				break;
280 			}
281 #if 0
282 		/*
283 		 * XXX
284 		 * syscons gets really confused if console resources are
285 		 * freed after the system has initialized.
286 		 */
287 		if (cn->cn_term != NULL)
288 			cn->cn_ops->cn_term(cn);
289 #endif
290 		return;
291 	}
292 }
293 
294 void
295 cnselect(struct consdev *cn)
296 {
297 	struct cn_device *cnd;
298 
299 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
300 		if (cnd->cnd_cn != cn)
301 			continue;
302 		if (cnd == STAILQ_FIRST(&cn_devlist))
303 			return;
304 		STAILQ_REMOVE(&cn_devlist, cnd, cn_device, cnd_next);
305 		STAILQ_INSERT_HEAD(&cn_devlist, cnd, cnd_next);
306 		ttyconsdev_select(cnd->cnd_cn->cn_name);
307 		return;
308 	}
309 }
310 
311 void
312 cnavailable(struct consdev *cn, int available)
313 {
314 	int i;
315 
316 	for (i = 0; i < CNDEVTAB_SIZE; i++) {
317 		if (cn_devtab[i].cnd_cn == cn)
318 			break;
319 	}
320 	if (available) {
321 		if (i < CNDEVTAB_SIZE)
322 			cons_avail_mask |= (1 << i);
323 		cn->cn_flags &= ~CN_FLAG_NOAVAIL;
324 	} else {
325 		if (i < CNDEVTAB_SIZE)
326 			cons_avail_mask &= ~(1 << i);
327 		cn->cn_flags |= CN_FLAG_NOAVAIL;
328 	}
329 }
330 
331 int
332 cnunavailable(void)
333 {
334 
335 	return (cons_avail_mask == 0);
336 }
337 
338 /*
339  * sysctl_kern_console() provides output parseable in conscontrol(1).
340  */
341 static int
342 sysctl_kern_console(SYSCTL_HANDLER_ARGS)
343 {
344 	struct cn_device *cnd;
345 	struct consdev *cp, **list;
346 	char *p;
347 	bool delete;
348 	int error;
349 	struct sbuf *sb;
350 
351 	sb = sbuf_new(NULL, NULL, CNDEVPATHMAX * 2, SBUF_AUTOEXTEND |
352 	    SBUF_INCLUDENUL);
353 	if (sb == NULL)
354 		return (ENOMEM);
355 	sbuf_clear(sb);
356 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next)
357 		sbuf_printf(sb, "%s,", cnd->cnd_cn->cn_name);
358 	sbuf_putc(sb, '/');
359 	SET_FOREACH(list, cons_set) {
360 		cp = *list;
361 		if (cp->cn_name[0] != '\0')
362 			sbuf_printf(sb, "%s,", cp->cn_name);
363 	}
364 	sbuf_finish(sb);
365 	error = sysctl_handle_string(oidp, sbuf_data(sb), sbuf_len(sb), req);
366 	if (error == 0 && req->newptr != NULL) {
367 		p = sbuf_data(sb);
368 		error = ENXIO;
369 		delete = false;
370 		if (*p == '-') {
371 			delete = true;
372 			p++;
373 		}
374 		SET_FOREACH(list, cons_set) {
375 			cp = *list;
376 			if (strcmp(p, cp->cn_name) != 0)
377 				continue;
378 			if (delete) {
379 				cnremove(cp);
380 				error = 0;
381 			} else {
382 				error = cnadd(cp);
383 				if (error == 0)
384 					cnselect(cp);
385 			}
386 			break;
387 		}
388 	}
389 	sbuf_delete(sb);
390 	return (error);
391 }
392 
393 SYSCTL_PROC(_kern, OID_AUTO, console,
394     CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 0, 0,
395     sysctl_kern_console, "A",
396     "Console device control");
397 
398 void
399 cngrab(void)
400 {
401 	struct cn_device *cnd;
402 	struct consdev *cn;
403 
404 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
405 		cn = cnd->cnd_cn;
406 		if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG))
407 			cn->cn_ops->cn_grab(cn);
408 	}
409 }
410 
411 void
412 cnungrab(void)
413 {
414 	struct cn_device *cnd;
415 	struct consdev *cn;
416 
417 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
418 		cn = cnd->cnd_cn;
419 		if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG))
420 			cn->cn_ops->cn_ungrab(cn);
421 	}
422 }
423 
424 void
425 cnresume(void)
426 {
427 	struct cn_device *cnd;
428 	struct consdev *cn;
429 
430 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
431 		cn = cnd->cnd_cn;
432 		if (cn->cn_ops->cn_resume != NULL)
433 			cn->cn_ops->cn_resume(cn);
434 	}
435 }
436 
437 /*
438  * Low level console routines.
439  */
440 int
441 cngetc(void)
442 {
443 	int c;
444 
445 	if (cn_mute)
446 		return (-1);
447 	while ((c = cncheckc()) == -1)
448 		cpu_spinwait();
449 	if (c == '\r')
450 		c = '\n';		/* console input is always ICRNL */
451 	return (c);
452 }
453 
454 int
455 cncheckc(void)
456 {
457 	struct cn_device *cnd;
458 	struct consdev *cn;
459 	int c;
460 
461 	if (cn_mute)
462 		return (-1);
463 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
464 		cn = cnd->cnd_cn;
465 		if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG)) {
466 			c = cn->cn_ops->cn_getc(cn);
467 			if (c != -1)
468 				return (c);
469 		}
470 	}
471 	return (-1);
472 }
473 
474 void
475 cngets(char *cp, size_t size, int visible)
476 {
477 	char *lp, *end;
478 	int c;
479 
480 	cngrab();
481 
482 	lp = cp;
483 	end = cp + size - 1;
484 	for (;;) {
485 		c = cngetc() & 0177;
486 		switch (c) {
487 		case '\n':
488 		case '\r':
489 			cnputc(c);
490 			*lp = '\0';
491 			cnungrab();
492 			return;
493 		case '\b':
494 		case '\177':
495 			if (lp > cp) {
496 				if (visible)
497 					cnputs("\b \b");
498 				lp--;
499 			}
500 			continue;
501 		case '\0':
502 			continue;
503 		default:
504 			if (lp < end) {
505 				switch (visible) {
506 				case GETS_NOECHO:
507 					break;
508 				case GETS_ECHOPASS:
509 					cnputc('*');
510 					break;
511 				default:
512 					cnputc(c);
513 					break;
514 				}
515 				*lp++ = c;
516 			}
517 		}
518 	}
519 }
520 
521 void
522 cnputc(int c)
523 {
524 	struct cn_device *cnd;
525 	struct consdev *cn;
526 	const char *cp;
527 
528 #ifdef EARLY_PRINTF
529 	if (early_putc != NULL) {
530 		if (c == '\n')
531 			early_putc('\r');
532 		early_putc(c);
533 		return;
534 	}
535 #endif
536 
537 	if (cn_mute || c == '\0')
538 		return;
539 	STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
540 		cn = cnd->cnd_cn;
541 		if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG)) {
542 			if (c == '\n')
543 				cn->cn_ops->cn_putc(cn, '\r');
544 			cn->cn_ops->cn_putc(cn, c);
545 		}
546 	}
547 	if (console_pausing && c == '\n' && !kdb_active) {
548 		for (cp = console_pausestr; *cp != '\0'; cp++)
549 			cnputc(*cp);
550 		cngrab();
551 		if (cngetc() == '.')
552 			console_pausing = false;
553 		cnungrab();
554 		cnputc('\r');
555 		for (cp = console_pausestr; *cp != '\0'; cp++)
556 			cnputc(' ');
557 		cnputc('\r');
558 	}
559 }
560 
561 void
562 cnputsn(const char *p, size_t n)
563 {
564 	size_t i;
565 	bool unlock_reqd = false;
566 
567 	if (mtx_initialized(&cnputs_mtx)) {
568 		/*
569 		 * NOTE: Debug prints and/or witness printouts in
570 		 * console driver clients can cause the "cnputs_mtx"
571 		 * mutex to recurse. Simply return if that happens.
572 		 */
573 		if (mtx_owned(&cnputs_mtx))
574 			return;
575 		mtx_lock_spin(&cnputs_mtx);
576 		unlock_reqd = true;
577 	}
578 
579 	for (i = 0; i < n; i++)
580 		cnputc(p[i]);
581 
582 	if (unlock_reqd)
583 		mtx_unlock_spin(&cnputs_mtx);
584 }
585 
586 void
587 cnputs(const char *p)
588 {
589 	cnputsn(p, strlen(p));
590 }
591 
592 static unsigned int consmsgbuf_size = 65536;
593 SYSCTL_UINT(_kern, OID_AUTO, consmsgbuf_size, CTLFLAG_RWTUN, &consmsgbuf_size,
594     0, "Console tty buffer size");
595 
596 /*
597  * Redirect console output to a tty.
598  */
599 int
600 constty_set(struct tty *tp)
601 {
602 	int size = consmsgbuf_size;
603 	void *buf = NULL;
604 
605 	tty_assert_locked(tp);
606 	if (constty == tp)
607 		return (0);
608 	if (constty != NULL)
609 		return (EBUSY);
610 
611 	if (consbuf == NULL) {
612 		tty_unlock(tp);
613 		buf = malloc(size, M_TTYCONS, M_WAITOK);
614 		tty_lock(tp);
615 	}
616 	mtx_lock(&constty_mtx);
617 	if (constty != NULL) {
618 		mtx_unlock(&constty_mtx);
619 		free(buf, M_TTYCONS);
620 		return (EBUSY);
621 	}
622 	if (consbuf == NULL) {
623 		consbuf = buf;
624 		msgbuf_init(&consmsgbuf, buf, size);
625 	} else
626 		free(buf, M_TTYCONS);
627 	constty = tp;
628 	mtx_unlock(&constty_mtx);
629 
630 	callout_init_mtx(&conscallout, tty_getlock(tp), 0);
631 	constty_timeout(tp);
632 	return (0);
633 }
634 
635 /*
636  * Disable console redirection to a tty.
637  */
638 int
639 constty_clear(struct tty *tp)
640 {
641 	int c;
642 
643 	tty_assert_locked(tp);
644 	if (constty != tp)
645 		return (ENXIO);
646 	callout_stop(&conscallout);
647 	mtx_lock(&constty_mtx);
648 	constty = NULL;
649 	mtx_unlock(&constty_mtx);
650 	while ((c = msgbuf_getchar(&consmsgbuf)) != -1)
651 		cnputc(c);
652 	/* We never free consbuf because it can still be in use. */
653 	return (0);
654 }
655 
656 /* Times per second to check for pending console tty messages. */
657 static int constty_wakeups_per_second = 15;
658 SYSCTL_INT(_kern, OID_AUTO, constty_wakeups_per_second, CTLFLAG_RW,
659     &constty_wakeups_per_second, 0,
660     "Times per second to check for pending console tty messages");
661 
662 static void
663 constty_timeout(void *arg)
664 {
665 	struct tty *tp = arg;
666 	int c;
667 
668 	tty_assert_locked(tp);
669 	while ((c = msgbuf_getchar(&consmsgbuf)) != -1) {
670 		if (tty_putchar(tp, c) < 0) {
671 			constty_clear(tp);
672 			return;
673 		}
674 	}
675 	callout_reset_sbt(&conscallout, SBT_1S / constty_wakeups_per_second,
676 	    0, constty_timeout, tp, C_PREL(1));
677 }
678 
679 /*
680  * Sysbeep(), if we have hardware for it
681  */
682 
683 #ifdef HAS_TIMER_SPKR
684 
685 static bool beeping;
686 static struct callout beeping_timer;
687 
688 static void
689 sysbeepstop(void *chan)
690 {
691 
692 	timer_spkr_release();
693 	beeping = false;
694 }
695 
696 int
697 sysbeep(int pitch, sbintime_t duration)
698 {
699 
700 	if (timer_spkr_acquire()) {
701 		if (!beeping) {
702 			/* Something else owns it. */
703 			return (EBUSY);
704 		}
705 	}
706 	timer_spkr_setfreq(pitch);
707 	if (!beeping) {
708 		beeping = true;
709 		callout_reset_sbt(&beeping_timer, duration, 0, sysbeepstop,
710 		    NULL, C_PREL(5));
711 	}
712 	return (0);
713 }
714 
715 static void
716 sysbeep_init(void *unused)
717 {
718 
719 	callout_init(&beeping_timer, 1);
720 }
721 SYSINIT(sysbeep, SI_SUB_SOFTINTR, SI_ORDER_ANY, sysbeep_init, NULL);
722 #else
723 
724 /*
725  * No hardware, no sound
726  */
727 
728 int
729 sysbeep(int pitch __unused, sbintime_t duration __unused)
730 {
731 
732 	return (ENODEV);
733 }
734 
735 #endif
736 
737 /*
738  * Temporary support for sc(4) to vt(4) transition.
739  */
740 static char vty_name[16];
741 SYSCTL_STRING(_kern, OID_AUTO, vty, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, vty_name,
742     0, "Console vty driver");
743 
744 int
745 vty_enabled(unsigned vty)
746 {
747 	static unsigned vty_selected = 0;
748 
749 	if (vty_selected == 0) {
750 		TUNABLE_STR_FETCH("kern.vty", vty_name, sizeof(vty_name));
751 		do {
752 #if defined(DEV_SC)
753 			if (strcmp(vty_name, "sc") == 0) {
754 				vty_selected = VTY_SC;
755 				break;
756 			}
757 #endif
758 #if defined(DEV_VT)
759 			if (strcmp(vty_name, "vt") == 0) {
760 				vty_selected = VTY_VT;
761 				break;
762 			}
763 #endif
764 #if defined(DEV_VT)
765 			vty_selected = VTY_VT;
766 #elif defined(DEV_SC)
767 			vty_selected = VTY_SC;
768 #endif
769 		} while (0);
770 
771 		if (vty_selected == VTY_VT)
772 			strcpy(vty_name, "vt");
773 		else if (vty_selected == VTY_SC)
774 			strcpy(vty_name, "sc");
775 	}
776 	return ((vty_selected & vty) != 0);
777 }
778