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kernel/linux-rt-4.4.41/arch/um/drivers/stderr_console.c 1.64 KB
5113f6f70   김현기   kernel add
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  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/console.h>
  
  #include "chan_user.h"
  
  /* ----------------------------------------------------------------------------- */
  /* trivial console driver -- simply dump everything to stderr                    */
  
  /*
   * Don't register by default -- as this registers very early in the
   * boot process it becomes the default console.
   *
   * Initialized at init time.
   */
  static int use_stderr_console = 0;
  
  static void stderr_console_write(struct console *console, const char *string,
  				 unsigned len)
  {
  	generic_write(2 /* stderr */, string, len, NULL);
  }
  
  static struct console stderr_console = {
  	.name		= "stderr",
  	.write		= stderr_console_write,
  	.flags		= CON_PRINTBUFFER,
  };
  
  static int __init stderr_console_init(void)
  {
  	if (use_stderr_console)
  		register_console(&stderr_console);
  	return 0;
  }
  console_initcall(stderr_console_init);
  
  static int stderr_setup(char *str)
  {
  	if (!str)
  		return 0;
  	use_stderr_console = simple_strtoul(str,&str,0);
  	return 1;
  }
  __setup("stderr=", stderr_setup);
  
  /* The previous behavior of not unregistering led to /dev/console being
   * impossible to open.  My FC5 filesystem started having init die, and the
   * system panicing because of this.  Unregistering causes the real
   * console to become the default console, and /dev/console can then be
   * opened.  Making this an initcall makes this happen late enough that
   * there is no added value in dumping everything to stderr, and the
   * normal console is good enough to show you all available output.
   */
  static int __init unregister_stderr(void)
  {
  	unregister_console(&stderr_console);
  
  	return 0;
  }
  
  __initcall(unregister_stderr);