Debug Logs

Greg Freemyer greg.freemyer at
Thu Jan 20 14:15:49 EST 2011

On Thu, Jan 20, 2011 at 2:05 PM, Denis Kirjanov <kirjanov at> wrote:
> On Thu, Jan 20, 2011 at 3:04 PM, sugnan prabhu <sugnan.prabhu at> wrote:
>> Hi Mulyadi,
>>       Finally after making some study on the dprintk source, i found that it
>> can be enable by setting the config CONFIG_CPU_FREQ_DEBUG
>> But the above link say that i need to boot the kernel with cpufreq.debug=7,
>> am not getting how to do that.
> It is a sysctl variable.
> sysctl -w debug.cpufreq.verbose=7

The kernel accepts arguments just like anything else and you pass them
in when you boot the kernel.  They can often be modified later, but do
it the easy way for now, just pass it in as argument to the kernel.

If you're using grub, in your menu.lst file you should have an entry like:

title Desktop -- openSUSE 11.3 -
    root (hd0,4)
    kernel /boot/vmlinuz-
resume=/dev/disk/by-id/ata-ST3250310AS_9RY00PYW-part1 splash=silent
showopts vga=0x31a
    initrd /boot/initrd-

Just add cpufreq.debug=7 at the end of the kernel boot line.


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