Linux内核日志开关

1、让pr_debug能输出

--- a/kernel/printk/printk.c

+++ b/kernel/printk/printk.c

@@ -59,7 +59,7 @@

/* We show everything that is MOREimportant than this.. */

#define MINIMUM_CONSOLE_LOGLEVEL 1 /*Minimum loglevel we let people use */

-#define DEFAULT_CONSOLE_LOGLEVEL 7 /*anything MORE serious than KERN_DEBUG */

+#define DEFAULT_CONSOLE_LOGLEVEL 8 /*anything MORE serious than KERN_DEBUG */

int console_printk[4] = {

DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */

2、让模块内代码都能输出

--- a/drivers/of/Makefile

+++ b/drivers/of/Makefile

EXTRA_CFLAGS += -DDEBUG

3、让每个文件输出

--- a/drivers/of/Makefile

+++ b/drivers/of/Makefile

文件include之前加define DEBUG

或者Makefile里面增加

pr_debug()

    Some files call pr_debug(), which is ordinarily an empty macro that discards
    its arguments at compile time.  To enable debugging output, build the
    appropriate file with -DDEBUG by adding

      CFLAGS_[filename].o := -DDEBUG

    to the makefile.

    For example, to see all attempts to spawn a usermode helper (such as
    /sbin/hotplug), add to lib/Makefile the line:

        CFLAGS_kobject_uevent.o := -DDEBUG

    Then boot the new kernel, do something that spawns a usermode helper, and
    use the "dmesg" command to view the pr_debug() output.

4、内核打印控制

d，lx，ld，，lu，这几个都是输出32位的
hd，hx，hu，这几个都是输出16位数据的，
hhd，hhx，hhu，这几个都是输出8位的，
lld，ll，llu，llx，这几个都是输出64位的，