arch/um/drivers/stderr_console.c

   1 #include <linux/init.h>
   2 #include <linux/console.h>
   3
   4 #include "chan_user.h"
   5
   6 /* ----------------------------------------------------------------------------- */
   7 /* trivial console driver -- simply dump everything to stderr                    */
   8
   9 /*
  10  * Don't register by default -- as this registeres very early in the
  11  * boot process it becomes the default console.
  12  */
  13 static int use_stderr_console = 0;
  14
  15 static void stderr_console_write(struct console *console, const char *string,
  16                                  unsigned len)
  17 {
  18         generic_write(2 /* stderr */, string, len, NULL);
  19 }
  20
  21 static struct console stderr_console = {
  22         .name           = "stderr",
  23         .write          = stderr_console_write,
  24         .flags          = CON_PRINTBUFFER,
  25 };
  26
  27 static int __init stderr_console_init(void)
  28 {
  29         if (use_stderr_console)
  30                 register_console(&stderr_console);
  31         return 0;
  32 }
  33 console_initcall(stderr_console_init);
  34
  35 static int stderr_setup(char *str)
  36 {
  37         if (!str)
  38                 return 0;
  39         use_stderr_console = simple_strtoul(str,&str,0);
  40         return 1;
  41 }
  42 __setup("stderr=", stderr_setup);
  43
  44 /* The previous behavior of not unregistering led to /dev/console being
  45  * impossible to open.  My FC5 filesystem started having init die, and the
  46  * system panicing because of this.  Unregistering causes the real
  47  * console to become the default console, and /dev/console can then be
  48  * opened.  Making this an initcall makes this happen late enough that
  49  * there is no added value in dumping everything to stderr, and the
  50  * normal console is good enough to show you all available output.
  51  */
  52 static int __init unregister_stderr(void)
  53 {
  54         unregister_console(&stderr_console);
  55
  56         return 0;
  57 }
  58
  59 __initcall(unregister_stderr);