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

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

arch/um/Kconfig.debug

+10 −0
Original line number Diff line number Diff line
@@ -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

arch/um/include/shared/os.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/um/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/um/kernel/early_printk.c

0 → 100644
+33 −0
Original line number Diff line number Diff line 
/*

 * 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);

arch/um/os-Linux/util.c

+5 −0
Original line number Diff line number Diff line
@@ -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);

}