lkml.org 
[lkml]   [2011]   [May]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 3/7] um: add earlyprintk support
    Date
    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>
    ---
    arch/um/Kconfig.debug | 10 ++++++++++
    arch/um/include/shared/os.h | 1 +
    arch/um/kernel/Makefile | 1 +
    arch/um/kernel/early_printk.c | 33 +++++++++++++++++++++++++++++++++
    arch/um/os-Linux/util.c | 5 +++++
    5 files changed, 50 insertions(+), 0 deletions(-)
    create mode 100644 arch/um/kernel/early_printk.c

    diff --git a/arch/um/Kconfig.debug b/arch/um/Kconfig.debug
    index 8fce5e5..85c86edd 100644
    --- a/arch/um/Kconfig.debug
    +++ b/arch/um/Kconfig.debug
    @@ -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
    diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
    index f06a5da..83c7c2e 100644
    --- a/arch/um/include/shared/os.h
    +++ b/arch/um/include/shared/os.h
    @@ -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);
    diff --git a/arch/um/kernel/Makefile b/arch/um/kernel/Makefile
    index 1119233..c4491c1 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 \
    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

    diff --git a/arch/um/kernel/early_printk.c b/arch/um/kernel/early_printk.c
    new file mode 100644
    index 0000000..ec649bf
    --- /dev/null
    +++ b/arch/um/kernel/early_printk.c
    @@ -0,0 +1,33 @@
    +/*
    + * 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);
    diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
    index 42827ca..5803b18 100644
    --- a/arch/um/os-Linux/util.c
    +++ b/arch/um/os-Linux/util.c
    @@ -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);
    +}
    --
    1.7.4.2


    \
     
     \ /
      Last update: 2011-05-22 16:53    [W:0.025 / U:59.020 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site