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      1 /*	$NetBSD: cninit.c,v 1.14 2020/07/29 01:55:58 uwe Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1988 University of Utah.
      5  * Copyright (c) 1990, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  *
      8  * This code is derived from software contributed to Berkeley by
      9  * the Systems Programming Group of the University of Utah Computer
     10  * Science Department.
     11  *
     12  * Redistribution and use in source and binary forms, with or without
     13  * modification, are permitted provided that the following conditions
     14  * are met:
     15  * 1. Redistributions of source code must retain the above copyright
     16  *    notice, this list of conditions and the following disclaimer.
     17  * 2. Redistributions in binary form must reproduce the above copyright
     18  *    notice, this list of conditions and the following disclaimer in the
     19  *    documentation and/or other materials provided with the distribution.
     20  * 3. Neither the name of the University nor the names of its contributors
     21  *    may be used to endorse or promote products derived from this software
     22  *    without specific prior written permission.
     23  *
     24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     34  * SUCH DAMAGE.
     35  *
     36  * from: Utah $Hdr: cons.c 1.7 92/01/21$
     37  *
     38  *	@(#)cons.c	8.2 (Berkeley) 1/12/94
     39  */
     40 
     41 #include <sys/cdefs.h>
     42 __KERNEL_RCSID(0, "$NetBSD: cninit.c,v 1.14 2020/07/29 01:55:58 uwe Exp $");
     43 
     44 #include <sys/param.h>
     45 #include <sys/proc.h>
     46 #include <sys/systm.h>
     47 #include <sys/buf.h>
     48 #include <sys/ioctl.h>
     49 #include <sys/tty.h>
     50 #include <sys/file.h>
     51 #include <sys/conf.h>
     52 #include <sys/vnode.h>
     53 
     54 #include <dev/cons.h>
     55 
     56 void
     57 cninit(void)
     58 {
     59 	struct consdev *bestMatch;
     60 	struct consdev *cp;
     61 
     62 	/*
     63 	 * Collect information about all possible consoles
     64 	 * and find the one with highest priority
     65 	 */
     66 	bestMatch = NULL;
     67 	for (cp = constab; cp->cn_probe; cp++) {
     68 		(*cp->cn_probe)(cp);
     69 		if (cp->cn_pri > CN_DEAD &&
     70 		    (bestMatch == NULL || cp->cn_pri > bestMatch->cn_pri)) {
     71 			bestMatch = cp;
     72 		}
     73 	}
     74 
     75 	/*
     76 	 * No console, we can handle it
     77 	 */
     78 	if (bestMatch == NULL)
     79 		return;
     80 
     81 	/*
     82 	 * Turn on console
     83 	 */
     84 	{
     85 		struct consdev *old_cn_tab = cn_tab;
     86 
     87 		/* cn_init may set cn_tab to self */
     88  		(*bestMatch->cn_init)(bestMatch);
     89 
     90 		/*
     91 		 * Now let everyone know we have an active console they can
     92 		 * use for diagnostics. If we use cn_tab in the search loop
     93 		 * then interrupts from the ethernet at boot may cause system
     94 		 * hang.
     95 		 */
     96 		if (cn_tab == old_cn_tab) /* if cn_init didn't, set it */
     97 			cn_tab = bestMatch;
     98 	}
     99 }
    100