The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_cons.c

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    1 /*-
    2  * Copyright (c) 1988 University of Utah.
    3  * Copyright (c) 1991 The Regents of the University of California.
    4  * Copyright (c) 1999 Michael Smith
    5  * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
    6  *
    7  * All rights reserved.
    8  *
    9  * This code is derived from software contributed to Berkeley by
   10  * the Systems Programming Group of the University of Utah Computer
   11  * Science Department.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  * 4. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      from: @(#)cons.c        7.2 (Berkeley) 5/9/91
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD: releng/11.0/sys/kern/kern_cons.c 283291 2015-05-22 17:05:21Z jkim $");
   42 
   43 #include "opt_ddb.h"
   44 #include "opt_syscons.h"
   45 
   46 #include <sys/param.h>
   47 #include <sys/systm.h>
   48 #include <sys/lock.h>
   49 #include <sys/mutex.h>
   50 #include <sys/conf.h>
   51 #include <sys/cons.h>
   52 #include <sys/fcntl.h>
   53 #include <sys/kdb.h>
   54 #include <sys/kernel.h>
   55 #include <sys/malloc.h>
   56 #include <sys/msgbuf.h>
   57 #include <sys/namei.h>
   58 #include <sys/priv.h>
   59 #include <sys/proc.h>
   60 #include <sys/queue.h>
   61 #include <sys/reboot.h>
   62 #include <sys/sysctl.h>
   63 #include <sys/sbuf.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 <machine/cpu.h>
   71 #include <machine/clock.h>
   72 
   73 static MALLOC_DEFINE(M_TTYCONS, "tty console", "tty console handling");
   74 
   75 struct cn_device {
   76         STAILQ_ENTRY(cn_device) cnd_next;
   77         struct          consdev *cnd_cn;
   78 };
   79 
   80 #define CNDEVPATHMAX    32
   81 #define CNDEVTAB_SIZE   4
   82 static struct cn_device cn_devtab[CNDEVTAB_SIZE];
   83 static STAILQ_HEAD(, cn_device) cn_devlist =
   84     STAILQ_HEAD_INITIALIZER(cn_devlist);
   85 
   86 int     cons_avail_mask = 0;    /* Bit mask. Each registered low level console
   87                                  * which is currently unavailable for inpit
   88                                  * (i.e., if it is in graphics mode) will have
   89                                  * this bit cleared.
   90                                  */
   91 static int cn_mute;
   92 static char *consbuf;                   /* buffer used by `consmsgbuf' */
   93 static struct callout conscallout;      /* callout for outputting to constty */
   94 struct msgbuf consmsgbuf;               /* message buffer for console tty */
   95 static u_char console_pausing;          /* pause after each line during probe */
   96 static char *console_pausestr=
   97 "<pause; press any key to proceed to next line or '.' to end pause mode>";
   98 struct tty *constty;                    /* pointer to console "window" tty */
   99 static struct mtx cnputs_mtx;           /* Mutex for cnputs(). */
  100 static int use_cnputs_mtx = 0;          /* != 0 if cnputs_mtx locking reqd. */
  101 
  102 static void constty_timeout(void *arg);
  103 
  104 static struct consdev cons_consdev;
  105 DATA_SET(cons_set, cons_consdev);
  106 SET_DECLARE(cons_set, struct consdev);
  107 
  108 void
  109 cninit(void)
  110 {
  111         struct consdev *best_cn, *cn, **list;
  112 
  113         /*
  114          * Check if we should mute the console (for security reasons perhaps)
  115          * It can be changes dynamically using sysctl kern.consmute
  116          * once we are up and going.
  117          * 
  118          */
  119         cn_mute = ((boothowto & (RB_MUTE
  120                         |RB_SINGLE
  121                         |RB_VERBOSE
  122                         |RB_ASKNAME)) == RB_MUTE);
  123 
  124         /*
  125          * Find the first console with the highest priority.
  126          */
  127         best_cn = NULL;
  128         SET_FOREACH(list, cons_set) {
  129                 cn = *list;
  130                 cnremove(cn);
  131                 /* Skip cons_consdev. */
  132                 if (cn->cn_ops == NULL)
  133                         continue;
  134                 cn->cn_ops->cn_probe(cn);
  135                 if (cn->cn_pri == CN_DEAD)
  136                         continue;
  137                 if (best_cn == NULL || cn->cn_pri > best_cn->cn_pri)
  138                         best_cn = cn;
  139                 if (boothowto & RB_MULTIPLE) {
  140                         /*
  141                          * Initialize console, and attach to it.
  142                          */
  143                         cn->cn_ops->cn_init(cn);
  144                         cnadd(cn);
  145                 }
  146         }
  147         if (best_cn == NULL)
  148                 return;
  149         if ((boothowto & RB_MULTIPLE) == 0) {
  150                 best_cn->cn_ops->cn_init(best_cn);
  151                 cnadd(best_cn);
  152         }
  153         if (boothowto & RB_PAUSE)
  154                 console_pausing = 1;
  155         /*
  156          * Make the best console the preferred console.
  157          */
  158         cnselect(best_cn);
  159 
  160 #ifdef EARLY_PRINTF
  161         /*
  162          * Release early console.
  163          */
  164         early_putc = NULL;
  165 #endif
  166 }
  167 
  168 void
  169 cninit_finish()
  170 {
  171         console_pausing = 0;
  172 } 
  173 
  174 /* add a new physical console to back the virtual console */
  175 int
  176 cnadd(struct consdev *cn)
  177 {
  178         struct cn_device *cnd;
  179         int i;
  180 
  181         STAILQ_FOREACH(cnd, &cn_devlist, cnd_next)
  182                 if (cnd->cnd_cn == cn)
  183                         return (0);
  184         for (i = 0; i < CNDEVTAB_SIZE; i++) {
  185                 cnd = &cn_devtab[i];
  186                 if (cnd->cnd_cn == NULL)
  187                         break;
  188         }
  189         if (cnd->cnd_cn != NULL)
  190                 return (ENOMEM);
  191         cnd->cnd_cn = cn;
  192         if (cn->cn_name[0] == '\0') {
  193                 /* XXX: it is unclear if/where this print might output */
  194                 printf("WARNING: console at %p has no name\n", cn);
  195         }
  196         STAILQ_INSERT_TAIL(&cn_devlist, cnd, cnd_next);
  197         if (STAILQ_FIRST(&cn_devlist) == cnd)
  198                 ttyconsdev_select(cnd->cnd_cn->cn_name);
  199 
  200         /* Add device to the active mask. */
  201         cnavailable(cn, (cn->cn_flags & CN_FLAG_NOAVAIL) == 0);
  202 
  203         return (0);
  204 }
  205 
  206 void
  207 cnremove(struct consdev *cn)
  208 {
  209         struct cn_device *cnd;
  210         int i;
  211 
  212         STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
  213                 if (cnd->cnd_cn != cn)
  214                         continue;
  215                 if (STAILQ_FIRST(&cn_devlist) == cnd)
  216                         ttyconsdev_select(NULL);
  217                 STAILQ_REMOVE(&cn_devlist, cnd, cn_device, cnd_next);
  218                 cnd->cnd_cn = NULL;
  219 
  220                 /* Remove this device from available mask. */
  221                 for (i = 0; i < CNDEVTAB_SIZE; i++) 
  222                         if (cnd == &cn_devtab[i]) {
  223                                 cons_avail_mask &= ~(1 << i);
  224                                 break;
  225                         }
  226 #if 0
  227                 /*
  228                  * XXX
  229                  * syscons gets really confused if console resources are
  230                  * freed after the system has initialized.
  231                  */
  232                 if (cn->cn_term != NULL)
  233                         cn->cn_ops->cn_term(cn);
  234 #endif
  235                 return;
  236         }
  237 }
  238 
  239 void
  240 cnselect(struct consdev *cn)
  241 {
  242         struct cn_device *cnd;
  243 
  244         STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
  245                 if (cnd->cnd_cn != cn)
  246                         continue;
  247                 if (cnd == STAILQ_FIRST(&cn_devlist))
  248                         return;
  249                 STAILQ_REMOVE(&cn_devlist, cnd, cn_device, cnd_next);
  250                 STAILQ_INSERT_HEAD(&cn_devlist, cnd, cnd_next);
  251                 ttyconsdev_select(cnd->cnd_cn->cn_name);
  252                 return;
  253         }
  254 }
  255 
  256 void
  257 cnavailable(struct consdev *cn, int available)
  258 {
  259         int i;
  260 
  261         for (i = 0; i < CNDEVTAB_SIZE; i++) {
  262                 if (cn_devtab[i].cnd_cn == cn)
  263                         break;
  264         }
  265         if (available) {
  266                 if (i < CNDEVTAB_SIZE)
  267                         cons_avail_mask |= (1 << i); 
  268                 cn->cn_flags &= ~CN_FLAG_NOAVAIL;
  269         } else {
  270                 if (i < CNDEVTAB_SIZE)
  271                         cons_avail_mask &= ~(1 << i);
  272                 cn->cn_flags |= CN_FLAG_NOAVAIL;
  273         }
  274 }
  275 
  276 int
  277 cnunavailable(void)
  278 {
  279 
  280         return (cons_avail_mask == 0);
  281 }
  282 
  283 /*
  284  * sysctl_kern_console() provides output parseable in conscontrol(1).
  285  */
  286 static int
  287 sysctl_kern_console(SYSCTL_HANDLER_ARGS)
  288 {
  289         struct cn_device *cnd;
  290         struct consdev *cp, **list;
  291         char *p;
  292         int delete, error;
  293         struct sbuf *sb;
  294 
  295         sb = sbuf_new(NULL, NULL, CNDEVPATHMAX * 2, SBUF_AUTOEXTEND |
  296             SBUF_INCLUDENUL);
  297         if (sb == NULL)
  298                 return (ENOMEM);
  299         sbuf_clear(sb);
  300         STAILQ_FOREACH(cnd, &cn_devlist, cnd_next)
  301                 sbuf_printf(sb, "%s,", cnd->cnd_cn->cn_name);
  302         sbuf_printf(sb, "/");
  303         SET_FOREACH(list, cons_set) {
  304                 cp = *list;
  305                 if (cp->cn_name[0] != '\0')
  306                         sbuf_printf(sb, "%s,", cp->cn_name);
  307         }
  308         sbuf_finish(sb);
  309         error = sysctl_handle_string(oidp, sbuf_data(sb), sbuf_len(sb), req);
  310         if (error == 0 && req->newptr != NULL) {
  311                 p = sbuf_data(sb);
  312                 error = ENXIO;
  313                 delete = 0;
  314                 if (*p == '-') {
  315                         delete = 1;
  316                         p++;
  317                 }
  318                 SET_FOREACH(list, cons_set) {
  319                         cp = *list;
  320                         if (strcmp(p, cp->cn_name) != 0)
  321                                 continue;
  322                         if (delete) {
  323                                 cnremove(cp);
  324                                 error = 0;
  325                         } else {
  326                                 error = cnadd(cp);
  327                                 if (error == 0)
  328                                         cnselect(cp);
  329                         }
  330                         break;
  331                 }
  332         }
  333         sbuf_delete(sb);
  334         return (error);
  335 }
  336 
  337 SYSCTL_PROC(_kern, OID_AUTO, console, CTLTYPE_STRING|CTLFLAG_RW,
  338         0, 0, sysctl_kern_console, "A", "Console device control");
  339 
  340 /*
  341  * User has changed the state of the console muting.
  342  * This may require us to open or close the device in question.
  343  */
  344 static int
  345 sysctl_kern_consmute(SYSCTL_HANDLER_ARGS)
  346 {
  347         int error;
  348 
  349         error = sysctl_handle_int(oidp, &cn_mute, 0, req);
  350         if (error != 0 || req->newptr == NULL)
  351                 return (error);
  352         return (error);
  353 }
  354 
  355 SYSCTL_PROC(_kern, OID_AUTO, consmute, CTLTYPE_INT|CTLFLAG_RW,
  356         0, sizeof(cn_mute), sysctl_kern_consmute, "I",
  357         "State of the console muting");
  358 
  359 void
  360 cngrab()
  361 {
  362         struct cn_device *cnd;
  363         struct consdev *cn;
  364 
  365         STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
  366                 cn = cnd->cnd_cn;
  367                 if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG))
  368                         cn->cn_ops->cn_grab(cn);
  369         }
  370 }
  371 
  372 void
  373 cnungrab()
  374 {
  375         struct cn_device *cnd;
  376         struct consdev *cn;
  377 
  378         STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
  379                 cn = cnd->cnd_cn;
  380                 if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG))
  381                         cn->cn_ops->cn_ungrab(cn);
  382         }
  383 }
  384 
  385 /*
  386  * Low level console routines.
  387  */
  388 int
  389 cngetc(void)
  390 {
  391         int c;
  392 
  393         if (cn_mute)
  394                 return (-1);
  395         while ((c = cncheckc()) == -1)
  396                 cpu_spinwait();
  397         if (c == '\r')
  398                 c = '\n';               /* console input is always ICRNL */
  399         return (c);
  400 }
  401 
  402 int
  403 cncheckc(void)
  404 {
  405         struct cn_device *cnd;
  406         struct consdev *cn;
  407         int c;
  408 
  409         if (cn_mute)
  410                 return (-1);
  411         STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
  412                 cn = cnd->cnd_cn;
  413                 if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG)) {
  414                         c = cn->cn_ops->cn_getc(cn);
  415                         if (c != -1)
  416                                 return (c);
  417                 }
  418         }
  419         return (-1);
  420 }
  421 
  422 void
  423 cngets(char *cp, size_t size, int visible)
  424 {
  425         char *lp, *end;
  426         int c;
  427 
  428         cngrab();
  429 
  430         lp = cp;
  431         end = cp + size - 1;
  432         for (;;) {
  433                 c = cngetc() & 0177;
  434                 switch (c) {
  435                 case '\n':
  436                 case '\r':
  437                         cnputc(c);
  438                         *lp = '\0';
  439                         cnungrab();
  440                         return;
  441                 case '\b':
  442                 case '\177':
  443                         if (lp > cp) {
  444                                 if (visible)
  445                                         cnputs("\b \b");
  446                                 lp--;
  447                         }
  448                         continue;
  449                 case '\0':
  450                         continue;
  451                 default:
  452                         if (lp < end) {
  453                                 switch (visible) {
  454                                 case GETS_NOECHO:
  455                                         break;
  456                                 case GETS_ECHOPASS:
  457                                         cnputc('*');
  458                                         break;
  459                                 default:
  460                                         cnputc(c);
  461                                         break;
  462                                 }
  463                                 *lp++ = c;
  464                         }
  465                 }
  466         }
  467 }
  468 
  469 void
  470 cnputc(int c)
  471 {
  472         struct cn_device *cnd;
  473         struct consdev *cn;
  474         char *cp;
  475 
  476 #ifdef EARLY_PRINTF
  477         if (early_putc != NULL) {
  478                 if (c == '\n')
  479                         early_putc('\r');
  480                 early_putc(c);
  481                 return;
  482         }
  483 #endif
  484 
  485         if (cn_mute || c == '\0')
  486                 return;
  487         STAILQ_FOREACH(cnd, &cn_devlist, cnd_next) {
  488                 cn = cnd->cnd_cn;
  489                 if (!kdb_active || !(cn->cn_flags & CN_FLAG_NODEBUG)) {
  490                         if (c == '\n')
  491                                 cn->cn_ops->cn_putc(cn, '\r');
  492                         cn->cn_ops->cn_putc(cn, c);
  493                 }
  494         }
  495         if (console_pausing && c == '\n' && !kdb_active) {
  496                 for (cp = console_pausestr; *cp != '\0'; cp++)
  497                         cnputc(*cp);
  498                 cngrab();
  499                 if (cngetc() == '.')
  500                         console_pausing = 0;
  501                 cnungrab();
  502                 cnputc('\r');
  503                 for (cp = console_pausestr; *cp != '\0'; cp++)
  504                         cnputc(' ');
  505                 cnputc('\r');
  506         }
  507 }
  508 
  509 void
  510 cnputs(char *p)
  511 {
  512         int c;
  513         int unlock_reqd = 0;
  514 
  515         if (use_cnputs_mtx) {
  516                 /*
  517                  * NOTE: Debug prints and/or witness printouts in
  518                  * console driver clients can cause the "cnputs_mtx"
  519                  * mutex to recurse. Simply return if that happens.
  520                  */
  521                 if (mtx_owned(&cnputs_mtx))
  522                         return;
  523                 mtx_lock_spin(&cnputs_mtx);
  524                 unlock_reqd = 1;
  525         }
  526 
  527         while ((c = *p++) != '\0')
  528                 cnputc(c);
  529 
  530         if (unlock_reqd)
  531                 mtx_unlock_spin(&cnputs_mtx);
  532 }
  533 
  534 static int consmsgbuf_size = 8192;
  535 SYSCTL_INT(_kern, OID_AUTO, consmsgbuf_size, CTLFLAG_RW, &consmsgbuf_size, 0,
  536     "Console tty buffer size");
  537 
  538 /*
  539  * Redirect console output to a tty.
  540  */
  541 void
  542 constty_set(struct tty *tp)
  543 {
  544         int size;
  545 
  546         KASSERT(tp != NULL, ("constty_set: NULL tp"));
  547         if (consbuf == NULL) {
  548                 size = consmsgbuf_size;
  549                 consbuf = malloc(size, M_TTYCONS, M_WAITOK);
  550                 msgbuf_init(&consmsgbuf, consbuf, size);
  551                 callout_init(&conscallout, 0);
  552         }
  553         constty = tp;
  554         constty_timeout(NULL);
  555 }
  556 
  557 /*
  558  * Disable console redirection to a tty.
  559  */
  560 void
  561 constty_clear(void)
  562 {
  563         int c;
  564 
  565         constty = NULL;
  566         if (consbuf == NULL)
  567                 return;
  568         callout_stop(&conscallout);
  569         while ((c = msgbuf_getchar(&consmsgbuf)) != -1)
  570                 cnputc(c);
  571         free(consbuf, M_TTYCONS);
  572         consbuf = NULL;
  573 }
  574 
  575 /* Times per second to check for pending console tty messages. */
  576 static int constty_wakeups_per_second = 5;
  577 SYSCTL_INT(_kern, OID_AUTO, constty_wakeups_per_second, CTLFLAG_RW,
  578     &constty_wakeups_per_second, 0,
  579     "Times per second to check for pending console tty messages");
  580 
  581 static void
  582 constty_timeout(void *arg)
  583 {
  584         int c;
  585 
  586         if (constty != NULL) {
  587                 tty_lock(constty);
  588                 while ((c = msgbuf_getchar(&consmsgbuf)) != -1) {
  589                         if (tty_putchar(constty, c) < 0) {
  590                                 tty_unlock(constty);
  591                                 constty = NULL;
  592                                 break;
  593                         }
  594                 }
  595 
  596                 if (constty != NULL)
  597                         tty_unlock(constty);
  598         }
  599         if (constty != NULL) {
  600                 callout_reset(&conscallout, hz / constty_wakeups_per_second,
  601                     constty_timeout, NULL);
  602         } else {
  603                 /* Deallocate the constty buffer memory. */
  604                 constty_clear();
  605         }
  606 }
  607 
  608 static void
  609 cn_drvinit(void *unused)
  610 {
  611 
  612         mtx_init(&cnputs_mtx, "cnputs_mtx", NULL, MTX_SPIN | MTX_NOWITNESS);
  613         use_cnputs_mtx = 1;
  614 }
  615 
  616 SYSINIT(cndev, SI_SUB_DRIVERS, SI_ORDER_MIDDLE, cn_drvinit, NULL);
  617 
  618 /*
  619  * Sysbeep(), if we have hardware for it
  620  */
  621 
  622 #ifdef HAS_TIMER_SPKR
  623 
  624 static int beeping;
  625 static struct callout beeping_timer;
  626 
  627 static void
  628 sysbeepstop(void *chan)
  629 {
  630 
  631         timer_spkr_release();
  632         beeping = 0;
  633 }
  634 
  635 int
  636 sysbeep(int pitch, int period)
  637 {
  638 
  639         if (timer_spkr_acquire()) {
  640                 if (!beeping) {
  641                         /* Something else owns it. */
  642                         return (EBUSY);
  643                 }
  644         }
  645         timer_spkr_setfreq(pitch);
  646         if (!beeping) {
  647                 beeping = period;
  648                 callout_reset(&beeping_timer, period, sysbeepstop, NULL);
  649         }
  650         return (0);
  651 }
  652 
  653 static void
  654 sysbeep_init(void *unused)
  655 {
  656 
  657         callout_init(&beeping_timer, 1);
  658 }
  659 SYSINIT(sysbeep, SI_SUB_SOFTINTR, SI_ORDER_ANY, sysbeep_init, NULL);
  660 #else
  661 
  662 /*
  663  * No hardware, no sound
  664  */
  665 
  666 int
  667 sysbeep(int pitch __unused, int period __unused)
  668 {
  669 
  670         return (ENODEV);
  671 }
  672 
  673 #endif
  674 
  675 /*
  676  * Temporary support for sc(4) to vt(4) transition.
  677  */
  678 static unsigned vty_prefer;
  679 static char vty_name[16];
  680 SYSCTL_STRING(_kern, OID_AUTO, vty, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, vty_name,
  681     0, "Console vty driver");
  682 
  683 int
  684 vty_enabled(unsigned vty)
  685 {
  686         static unsigned vty_selected = 0;
  687 
  688         if (vty_selected == 0) {
  689                 TUNABLE_STR_FETCH("kern.vty", vty_name, sizeof(vty_name));
  690                 do {
  691 #if defined(DEV_SC)
  692                         if (strcmp(vty_name, "sc") == 0) {
  693                                 vty_selected = VTY_SC;
  694                                 break;
  695                         }
  696 #endif
  697 #if defined(DEV_VT)
  698                         if (strcmp(vty_name, "vt") == 0) {
  699                                 vty_selected = VTY_VT;
  700                                 break;
  701                         }
  702 #endif
  703                         if (vty_prefer != 0) {
  704                                 vty_selected = vty_prefer;
  705                                 break;
  706                         }
  707 #if defined(DEV_VT)
  708                         vty_selected = VTY_VT;
  709 #elif defined(DEV_SC)
  710                         vty_selected = VTY_SC;
  711 #endif
  712                 } while (0);
  713 
  714                 if (vty_selected == VTY_VT)
  715                         strcpy(vty_name, "vt");
  716                 else if (vty_selected == VTY_SC)
  717                         strcpy(vty_name, "sc");
  718         }
  719         return ((vty_selected & vty) != 0);
  720 }
  721 
  722 void
  723 vty_set_preferred(unsigned vty)
  724 {
  725 
  726         vty_prefer = vty;
  727 #if !defined(DEV_SC)
  728         vty_prefer &= ~VTY_SC;
  729 #endif
  730 #if !defined(DEV_VT)
  731         vty_prefer &= ~VTY_VT;
  732 #endif
  733 }
  734 

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