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  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25
  26 #include <i386/mp.h>
  27 #include <i386/machine_routines.h>
  28
  29 void
  30 cnputc(char c)
  31 {
  32         boolean_t       nolock = mp_kdp_trap || !ml_get_interrupts_enabled();
  33
  34         /*
  35          * Note: this lock prevents other cpus interferring with the
  36          * output is this one character to the console (screen). It
  37          * does not prevent multiple printfs being interleaved - that's
  38          * the responsibility of the caller.  Without this lock,
  39          * an unreadable black-on-black or white-on-white display may result.
  40          * We avoid taking this lock, however, if we're in the debugger or
  41          * at interrupt level.
  42          */
  43         if (!nolock)
  44                 simple_lock(&mp_putc_lock);
  45         vcputc(0, 0, c);
  46         if (c == '\n')
  47                 vcputc(0, 0,'\r');
  48         if (!nolock)
  49                 simple_unlock(&mp_putc_lock);
  50 }