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
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