Commit d634f194 authored by Richard Weinberger's avatar Richard Weinberger Committed by Linus Torvalds

um: add earlyprintk support

User Mode Linux can also benefit from earlyprintk.  UML's earlyprintk
writes kernel messages directly to stdout.
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2525e70d
......@@ -37,4 +37,14 @@ config DEBUG_STACK_USAGE
stack seen so far.
This option will slow down process creation and destruction somewhat.
config EARLY_PRINTK
bool "Early printk"
default y
---help---
Write kernel log output directly to stdout.
This is useful for kernel debugging when your machine crashes very
early before the console code is initialized.
endmenu
......@@ -244,6 +244,7 @@ extern int raw(int fd);
extern void setup_machinename(char *machine_out);
extern void setup_hostinfo(char *buf, int len);
extern void os_dump_core(void) __attribute__ ((noreturn));
extern void um_early_printk(const char *s, unsigned int n);
/* time.c */
extern void idle_sleep(unsigned long long nsecs);
......
......@@ -17,6 +17,7 @@ obj-y = config.o exec.o exitcode.o init_task.o irq.o ksyms.o mem.o \
obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
obj-$(CONFIG_GPROF) += gprof_syms.o
obj-$(CONFIG_GCOV) += gmon_syms.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
USER_OBJS := config.o
......
/*
* Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/console.h>
#include <linux/init.h>
#include "os.h"
static void early_console_write(struct console *con, const char *s, unsigned int n)
{
um_early_printk(s, n);
}
static struct console early_console = {
.name = "earlycon",
.write = early_console_write,
.flags = CON_BOOT,
.index = -1,
};
static int __init setup_early_printk(char *buf)
{
register_console(&early_console);
return 0;
}
early_param("earlyprintk", setup_early_printk);
......@@ -139,3 +139,8 @@ void os_dump_core(void)
uml_abort();
}
void um_early_printk(const char *s, unsigned int n)
{
printf("%.*s", n, s);
}
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