osfmk/console/i386/serial_console.c

   1 /*
   2  * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22
  23 #include <i386/mp.h>
  24 #include <i386/machine_routines.h>
  25
  26 void
  27 cnputc(char c)
  28 {
  29         boolean_t       nolock = mp_kdp_trap || !ml_get_interrupts_enabled();
  30
  31         /*
  32          * Note: this lock prevents other cpus interferring with the
  33          * output is this one character to the console (screen). It
  34          * does not prevent multiple printfs being interleaved - that's
  35          * the responsibility of the caller.  Without this lock,
  36          * an unreadable black-on-black or white-on-white display may result.
  37          * We avoid taking this lock, however, if we're in the debugger or
  38          * at interrupt level.
  39          */
  40         if (!nolock)
  41                 simple_lock(&mp_putc_lock);
  42         vcputc(0, 0, c);
  43         if (c == '\n')
  44                 vcputc(0, 0,'\r');
  45         if (!nolock)
  46                 simple_unlock(&mp_putc_lock);
  47 }