Re: kernel debugging

From: Jesper Juhl
Date: Sun Jul 24 2005 - 09:03:37 EST

On 7/24/05, UmaMaheswari Devi <uma@xxxxxxxxxx> wrote:
> I am new to kernel hacking and am facing problems in trying to peek at the
> runtime values of some kernel variables using gdb.
> I am issuing the gdb command as follows:
> gdb vmlinux /proc/kcore
> This displays the message
> /proc/kcore: Operation not permitted
> before the (gdb) prompt is displayed.
> gdb then prints a value of 0 for any valid variable that is requested.
> vmlinux appears to be OK, as gdb correctly identifies undefined variables.
> The problem seems to be with /proc/kcore. This file has a permission of 400. I
> am using the Red Hat distribution.
> Any help is appreciated.
If you want to use gdb to debug the kernel you should probably
investigate UML (User Mode Linux). Take a look at this link :

Alternatives include kgdb -
and kdb -

You can also find many documents on Linux Kernel debugging aids and
techniques via google.

Jesper Juhl <jesper.juhl@xxxxxxxxx>
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