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authorRichard Weinberger <richard@nod.at>2011-05-24 20:13:01 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-05-25 11:39:41 -0400
commitd634f194d4e2e58d57927c812aca097e67a2287d (patch)
treeca17ff43725293ea0bda7a7d7e8ed23ad4f89e14 /arch/um
parent2525e70d492f8c7bbe1292db8fcd973607a56ac6 (diff)
um: add earlyprintk support
User Mode Linux can also benefit from earlyprintk. UML's earlyprintk writes kernel messages directly to stdout. Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um')
-rw-r--r--arch/um/Kconfig.debug10
-rw-r--r--arch/um/include/shared/os.h1
-rw-r--r--arch/um/kernel/Makefile1
-rw-r--r--arch/um/kernel/early_printk.c33
-rw-r--r--arch/um/os-Linux/util.c5
5 files changed, 50 insertions, 0 deletions
diff --git a/arch/um/Kconfig.debug b/arch/um/Kconfig.debug
index 8fce5e536b0f..85c86edd1e67 100644
--- a/arch/um/Kconfig.debug
+++ b/arch/um/Kconfig.debug
@@ -37,4 +37,14 @@ config DEBUG_STACK_USAGE
37 stack seen so far. 37 stack seen so far.
38 38
39 This option will slow down process creation and destruction somewhat. 39 This option will slow down process creation and destruction somewhat.
40
41config EARLY_PRINTK
42 bool "Early printk"
43 default y
44 ---help---
45 Write kernel log output directly to stdout.
46
47 This is useful for kernel debugging when your machine crashes very
48 early before the console code is initialized.
49
40endmenu 50endmenu
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index f06a5da71a8f..83c7c2ecd614 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -244,6 +244,7 @@ extern int raw(int fd);
244extern void setup_machinename(char *machine_out); 244extern void setup_machinename(char *machine_out);
245extern void setup_hostinfo(char *buf, int len); 245extern void setup_hostinfo(char *buf, int len);
246extern void os_dump_core(void) __attribute__ ((noreturn)); 246extern void os_dump_core(void) __attribute__ ((noreturn));
247extern void um_early_printk(const char *s, unsigned int n);
247 248
248/* time.c */ 249/* time.c */
249extern void idle_sleep(unsigned long long nsecs); 250extern void idle_sleep(unsigned long long nsecs);
diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
index 1119233597a1..c4491c15afb2 100644
--- a/arch/um/kernel/Makefile
+++ b/arch/um/kernel/Makefile
@@ -17,6 +17,7 @@ obj-y = config.o exec.o exitcode.o init_task.o irq.o ksyms.o mem.o \
17obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o 17obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
18obj-$(CONFIG_GPROF) += gprof_syms.o 18obj-$(CONFIG_GPROF) += gprof_syms.o
19obj-$(CONFIG_GCOV) += gmon_syms.o 19obj-$(CONFIG_GCOV) += gmon_syms.o
20obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
20 21
21USER_OBJS := config.o 22USER_OBJS := config.o
22 23
diff --git a/arch/um/kernel/early_printk.c b/arch/um/kernel/early_printk.c
new file mode 100644
index 000000000000..ec649bf72f68
--- /dev/null
+++ b/arch/um/kernel/early_printk.c
@@ -0,0 +1,33 @@
1/*
2 * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9#include <linux/kernel.h>
10#include <linux/console.h>
11#include <linux/init.h>
12#include "os.h"
13
14static void early_console_write(struct console *con, const char *s, unsigned int n)
15{
16 um_early_printk(s, n);
17}
18
19static struct console early_console = {
20 .name = "earlycon",
21 .write = early_console_write,
22 .flags = CON_BOOT,
23 .index = -1,
24};
25
26static int __init setup_early_printk(char *buf)
27{
28 register_console(&early_console);
29
30 return 0;
31}
32
33early_param("earlyprintk", setup_early_printk);
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index 42827cafa6af..5803b1887672 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -139,3 +139,8 @@ void os_dump_core(void)
139 139
140 uml_abort(); 140 uml_abort();
141} 141}
142
143void um_early_printk(const char *s, unsigned int n)
144{
145 printf("%.*s", n, s);
146}