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 */ 17 static int use_stderr_console = 0; 18 19 static void stderr_console_write(struct console *console, const char *string, 20 unsigned len) 21 { 22 generic_write(2 /* stderr */, string, len, NULL); 23 } 24 25 static struct console stderr_console = { 26 .name = "stderr", 27 .write = stderr_console_write, 28 .flags = CON_PRINTBUFFER, 29 }; 30 31 static int __init stderr_console_init(void) 32 { 33 if (use_stderr_console) 34 register_console(&stderr_console); 35 return 0; 36 } 37 console_initcall(stderr_console_init); 38 39 static 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 */ 56 static int __init unregister_stderr(void) 57 { 58 unregister_console(&stderr_console); 59 60 return 0; 61 } 62 63 __initcall(unregister_stderr); 64