Linux Kernel log Switch __linux

Linux kernel log switch

1, let Pr_debug can output

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

+++ B/KERNEL/PRINTK/PRINTK.C

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

/* We show everything which is moreimportant than this.. */

#define MINIMUM_CONSOLE_LOGLEVEL 1/*minimum loglevel We have 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, let the module inside the code can output

---a/drivers/of/makefile

+++ B/drivers/of/makefile

Extra_cflags + +-ddebug

3, let each file output

---a/drivers/of/makefile

+++ B/drivers/of/makefile

Add define DEBUG before file include

or makefile inside.

Pr_debug ()

    Some files Call Pr_debug (), which are ordinarily an empty macro-discards its
    arguments at compile t IME.  To enable debugging output, builds the
    appropriate file with-ddebug by adding

      cflags_[filename].o: =-ddebug

    t o the makefile.

    For example, to the 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 this spawns a usermode helper, and
    use The "DMESG" command to view the Pr_debug () output.
  

4. Kernel Print Control

D,lx,ld,,lu, these are all 32-bit output.
Hd,hx,hu, these are all output 16-bit data,
Hhd,hhx,hhu, these are all output 8 bits,
LLD,LL,LLU,LLX, these are all output 64 bits,