Re: kernel debugging

From: Jesper Juhl
Date: Sun Jul 24 2005 - 09:05:54 EST

On 7/24/05, Jesper Juhl <jesper.juhl@xxxxxxxxx> wrote:
> 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.
Ohh, and do search the LKML archives, kernel debuggers have been
discussed endlessly over the years on the list, so you should be able
to find many threads covering that.

Jesper Juhl <jesper.juhl@xxxxxxxxx>
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