Re: help with running systemtap

[p v <pvlogin at yahoo dot com>]

Thanks for the reply. I got little bit further but stap is still not working for me. These are the packages installed -

[root@robot ~]# rpm -qa | grep kernel
kernel-devel-2.6.25-14.fc9.i686
kernel-debuginfo-2.6.25-14.fc9.i686
kernel-headers-2.6.25-14.fc9.i386
kerneloops-0.10-11.fc9.i386
kernel-debuginfo-common-2.6.25-14.fc9.i686
kernel-2.6.25-14.fc9.i686

stap does find the debug info it needs to compile but it fails to insmod with "Invalid module format" -

[root@robot ~]# stap -v -k hello.stp
Pass 1: parsed user script and 38 library script(s) in 250usr/10sys/268real ms.
Pass 2: analyzed script: 1 probe(s), 1 function(s), 0 embed(s), 0 global(s) in 10usr/0sys/3real ms.
Pass 3: using cached /root/.systemtap/cache/2b/stap_2b11f1a63be8d5e9310e1f646ee698de_264.c
Pass 4: using cached /root/.systemtap/cache/2b/stap_2b11f1a63be8d5e9310e1f646ee698de_264.ko
Pass 5: starting run.
Error inserting module '/tmp/stapvQz24y/stap_2b11f1a63be8d5e9310e1f646ee698de_264.ko': Invalid module format
Pass 5: run completed in 0usr/0sys/4real ms.
Pass 5: run failed.  Try again with more '-v' (verbose) options.
Keeping temporary directory "/tmp/stapvQz24y"

and dmesg spits out -

stap_2b11f1a63be8d5e9310e1f646ee698de_264: version magic '2.6.25.14-108.fc9.i686 SMP mod_unload 686 4KSTACKS ' should be '2.6.25-14.fc9.i686 SMP mod_unload 686 4KSTACKS '

where is the wrong version coming from?

thanks

--pv




----- Original Message ----
From: Frank Ch. Eigler <fche@redhat.com>
To: p v <pvlogin@yahoo.com>
Cc: systemtap@sourceware.org
Sent: Friday, September 5, 2008 11:37:16 AM
Subject: Re: help with running systemtap


p v <pvlogin@yahoo.com> writes:

> I've read most of the FAQ's on the web (and more) but I still can't
> figure out what's wrong with my setup. I've installed fresh FC9 on
> top of which I did install a debug kernel rpm.

The confusion here is that fedora includes a fully separate "debug"
variant of the kernel that enables lockdep and other functions,
whereas systemtap needs the "-debuginfo" associated with any
particular kernel variant.  So, install "kernel-debug-debuginfo" and
"kernel-debug-devel".

> It's surprising that stap packages are installed although they are
> useless without some additional steps. [...]

One reason for this is that there is no convenient RPM syntax for
systemtap to declare a dependency upon a matching pair of
kernel-*-debuginfo and kernel-*-devel.

> Also how stable is stap? Is it stable enough to be run on production
> machines?

A number of organizations are using it in that capacity.  Most of them
carefully test their scripts first on a development machine.  The
nature of our failures is that things rarely fail on the former if
they worked on the latter.

- FChE