Re: kernel debugging

[Jesper Juhl]

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 :
> 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.
> 
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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