stderr_console.c (1719B)
1// SPDX-License-Identifier: GPL-2.0 2#include <linux/kernel.h> 3#include <linux/init.h> 4#include <linux/console.h> 5 6#include "chan_user.h" 7 8/* ----------------------------------------------------------------------------- */ 9/* trivial console driver -- simply dump everything to stderr */ 10 11/* 12 * Don't register by default -- as this registers very early in the 13 * boot process it becomes the default console. 14 * 15 * Initialized at init time. 16 */ 17static int use_stderr_console = 0; 18 19static void stderr_console_write(struct console *console, const char *string, 20 unsigned len) 21{ 22 generic_write(2 /* stderr */, string, len, NULL); 23} 24 25static struct console stderr_console = { 26 .name = "stderr", 27 .write = stderr_console_write, 28 .flags = CON_PRINTBUFFER, 29}; 30 31static int __init stderr_console_init(void) 32{ 33 if (use_stderr_console) 34 register_console(&stderr_console); 35 return 0; 36} 37console_initcall(stderr_console_init); 38 39static int stderr_setup(char *str) 40{ 41 if (!str) 42 return 0; 43 use_stderr_console = simple_strtoul(str,&str,0); 44 return 1; 45} 46__setup("stderr=", stderr_setup); 47 48/* The previous behavior of not unregistering led to /dev/console being 49 * impossible to open. My FC5 filesystem started having init die, and the 50 * system panicing because of this. Unregistering causes the real 51 * console to become the default console, and /dev/console can then be 52 * opened. Making this an initcall makes this happen late enough that 53 * there is no added value in dumping everything to stderr, and the 54 * normal console is good enough to show you all available output. 55 */ 56static int __init unregister_stderr(void) 57{ 58 unregister_console(&stderr_console); 59 60 return 0; 61} 62 63__initcall(unregister_stderr);