lkml.org 
[lkml]   [2010]   [Aug]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: why can't i use gdb to dump module variables anymore?
On 08/09/2010 11:06 AM, Robert P. J. Day wrote:
> On Sun, 8 Aug 2010, Jon Masters wrote:
>
>
>> On Jul 8, 2010, at 7:51 AM, Robert P. J. Day wrote:
>>
>>> (gdb) p rpjday_2
>>> Cannot access memory at address 0xffffffffa007c0b4
>>> (gdb) p rpjday_3
>>> Cannot access memory at address 0xffffffffa007c0b8
>>>
>> Did you ever get a reply to this one? Were you trying to do this
>> locally, by loading a kernel core or using kgdb?
>>
>
> never figured out what was happening here, used to work just fine
> for simple gdb debugging of the kernel; nowadays (at least on ubuntu),
> not so much. anyway, i'm in bahstahn for linuxcon, staying at the
> onyx hotel for first 3 days. my girlfriend is doing a bofs session:
>
> http://events.linuxfoundation.org/linuxcon2010/mckinnon
>
> anyway, regarding gdb, this was based on a column i wrote last
> year:
>
> http://www.linux.com/learn/linux-training/33991-the-kernel-newbie-corner-kernel-and-module-debugging-with-gdb
>
> where it worked just fine -- it's the technique described in LDD3.
> but now, on ubuntu 10.04, weirdness. i haven't looked at it closely
> again for a while, but if you have any ideas, i'm open to suggestions.
> maybe some odd security/selinux/??? setting?
>

I took a brief look at the instructions you had a the URL. It seemed
like something that should probably work ok unless that memory address
is really not accessible via /proc/kcore.

Depending on the age of the ubuntu system and if you have a serial port
or not, kgdb is actually enabled in the kernel and you could certainly
try the same test there.

It should also be possible to try out a gdb with kernel module awareness
on the /proc/kcore. If you want to try and debug it at some point
perhaps we'll cross paths at LinuxCON.

Jason


\
 
 \ /
  Last update: 2010-08-10 14:03    [W:0.075 / U:0.344 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site