[Crash-utility] Crash setup!

[Dave Anderson]

----- "Bhaskar Jayaraman" <Bhaskar.Jayaraman at lsi.com> wrote:

> Dave, my apologies for being ambiguous, I forgot to mention how I
> installed xen-3.3.0; since an upgrade of the xen kernel, which came
> with the CentOS 5.2 DVD, to xen-3.3.0 would fail the xen python
> scripts, a workaround was employed.
> So we first install CentOS w/o Xen and then bring in the xen-3.3.0
> sources and install it on top of this. In this procedure the crash.ko
> driver doesn't seem to be getting installed.
> Now I'm facing two issues: -
> 
> 1] I believe I will need the crash.ko driver to run the crash on a
> live kernel but I'm not able to find its source file in the linux
> sources that come with 3.3.0

As I've tried to stress in my previous responses, the Red Hat crash.ko module
is most likely *not* necessary in your case -- but more on that below...

With respect to the ramifications of applying xen-3.3.0 source code
(which includes Xensource's 2.6.18-based kernel, right?) on top of the
CentOS 5.2 source three, then it's to be expected that Xensource vmlinux
kernel doesn't include the /dev/crash driver -- that's a Red Hat only
concept.

> 
> 2] I believe we have to build a debug kernel for crash to work with
> it. However when I enable the compile kernel with debug info in "make
> menuconfig", and make in the /xen-3.3.0/linux-2.6.18-xen.hg directory
> and do a make on /xen-3.3.0 directory, I keep getting an error which
> says: -
> 

Sorry, I'm not going to be able to help you w/respect to upstream Xensource
kernel building.  Never done it, and I don't suppose I ever will...

However, there are several upstream xen junkies on this list, and
they may be able to help you out with generating a debug-full vmlinux.

> make -C /home/user/xen-3.3.0/linux-2.6.18-xen.hg
> O=/home/user/xen-3.3.0/build-linux-2.6.18-xen_x86_64 modules
>   Using /home/user/xen-3.3.0/linux-2.6.18-xen.hg as source for kernel
>   /home/user/xen-3.3.0/linux-2.6.18-xen.hg is not clean, please run
> 'make mrproper'
>   in the '/home/user/xen-3.3.0/linux-2.6.18-xen.hg' directory.
> make[5]: *** [prepare3] Error 1
> make[4]: *** [modules] Error 2
> make[3]: *** [modules] Error 2
> make[3]: Leaving directory
> `/home/user/xen-3.3.0/build-linux-2.6.18-xen_x86_64'
> make[2]: *** [build] Error 1
> make[2]: Leaving directory `/home/user/xen-3.3.0'
> make[1]: *** [linux-2.6-xen-install] Error 2
> make[1]: Leaving directory `/home/user/xen-3.3.0'
> make: *** [install-kernels] Error 1

BTW, did you do the preliminary "make mrproper" like it requests? 

Anyway, getting back to the /dev/crash driver issue...

Especially given that you are running on an x86_64, the course of
least resistance is to utilize the built-in /dev/mem driver and forget
about trying to shoe-horn the Red Hat /dev/crash driver into place.  

If /dev/mem doesn't work by default because the Xensource 2.6.18
vmlinux kernel has put restrictions on its use (like Red Hat does),
then just remove those restrictions and rebuild.

Dave