Re: kernel debugging

[Jesper Juhl <jesper.juhl@gmail.com>]

On 7/24/05, UmaMaheswari Devi <uma@cs.unc.edu> 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 :
http://user-mode-linux.sourceforge.net/debugging.html

Alternatives include kgdb - http://kgdb.sourceforge.net/ 
and kdb - http://oss.sgi.com/projects/kdb/

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

-- 
Jesper Juhl <jesper.juhl@gmail.com>
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