Where does systemtap look for debuginfo and sources ?

[Jim Keniston]

On Tue, 2010-04-13 at 11:21 -0400, Frank Ch. Eigler wrote:
> "A, Satheeshpaul (EXT-Other - IN/Bangalore)" <satheeshpaul.a.ext@nsn.com> writes:
> 
> > I am having trouble in probing a module that did not come with the RHEL
> > 5.4 distribution.
> 
> Systemtap does work with this configuration but only clumsily.
> 
> > I have installed the kernel-debuginfo & kernel-devel
> > packages. The kernel-debuginfo packages puts the debug-build modules
> > under "/usr/lib/debug/lib/modules/2.6.18-164.el5/kernel/" . I have
> > copied my module (built with -g and no optimisation) in this location. I
> > also copied the sources of this module under
> > "/usr/src/debug/kernel-2.6.18/linux-2.6.18.x86_64/net". But systemtap is
> > still not able to find the probe point.
> 
> If your .ko is not stripped, then you should need do nothing but copy
> it under /lib/modules/`uname -r`/kernel somewhere.  stap should find
> it, and its embedded dwarf data.
> 

This works for me if I insmod the .ko I want to probe BEFORE I start my
stap script.  If I start the stap script first, stap doesn't complain,
but doesn't probe the .ko after I insmod it.

Also, I see the following behavior, which I guess is consistent with the
above limitation:

tty1# insmod xxx.ko
tty2# stap probe_xxx.stp
[stap reports xxx.ko events]
tty1# rmmod xxx
tty1# insmod xxx.ko
[stap no longer reports xxx.ko events]

> 
> 
> - FChE

Jim