SystemTap vs. FC5 Xen kernels (was: 03-23-2006 Meeting minutes)

[Stone, Joshua I]

William Cohen wrote:
> Sometimes the options are turned off on purpose. Do the Xen kernels
> build with "CONFIG_KPROBES=y"?

yes
 
> If kernels are built, do the resulting kernels actually have kprobe
> support? It use to be that xen kernels copy and pasted code from other
> arches. What additional patches are needed to bring the kprobe support
> in the xen kernel in line with the various architectures?


In order to get the debug info working, I removed the change to
lib/Kconfig.debug (mentioned in my other email), but left the change in
arch/x86_64/kernel/entry-xen.S.  I suspect that more will need to be
done here before CONFIG_DEBUG_INFO really works completely, as there's
probably some reason it was disabled, but this is good enough for
testing SystemTap.

On both xen0 and xenU, all pass-5 tests succeed, except those that use
timer.profile.  (systemtap.base/timers.stp and
systemtap.maps/pmap_agg_overflow.stp).  It seems that the timer.profile
thinks it is registered successfully, but the callback is never
triggered.  I will investigate this further...


Josh