Re: Status of kernel marker support

[Mathieu Desnoyers <mathieu dot desnoyers at polymtl dot ca>]

* Vara Prasad (prasadav@us.ibm.com) wrote:
> I am forwarding this to Mathieu just in case he is not following the 
> SystemTap mailing list. Please include him in future markers discussion.
> 
> Mathieu, as you can see we are adding the support for markers in the 
> SystemTap and also trying to add markers patches to the kernel.
> Are we using the latest version of the markers patch or do you have more 
> updated versions?

Hi Vara,

That's a good news.

The best is to get the latest marker post I made on LKML, posted back
Fri, 28 Sep 2007 10:28:45. However, since you don't have the full
patchset to be merged in the -mm tree, it is probably best for me to
prepare a tarball. Here it is:
http://ltt.polymtl.ca/markers/markers-patches-for-2.6.23-rc8-mm2-02-10-2007.tar.bz2

Please keep in mind that it will break the tools you have, which depends
on the __markers_strings section to be a "real" section, not just a blob
of data.

In order to get the markers from the kernel image, you should use the
__start___markers and __stop___markers symbols. (since the __markers
section is packed in the .data section in the linker scripts, I think
__markers will just vanish) (see include/asm-generic/vmlinux.lds.h for
details).

To get the markers from the kernel modules, using the __markers sections
seems like a good solution.


> If we find bugs while using markers can we open them in the SystemTap 
> bugzilla?
> 

Sure, please keep me in CC so I can help you solving the problem.

Mathieu

> Thanks,
> Vara Prasad
> 
> Mike Mason wrote:
> 
> >David Smith wrote:
> >
> >>Mike Mason wrote:
> >>
> >>>What's the status of kernel marker support in SystemTap?  Should 
> >>>kernel.mark("<name>") work with Mathieu's latest patches?  Just 
> >>>curious because I tried and I'm seeing "no match for probe point" 
> >>>errors for markers I added to the kernel.
> >>
> >>
> >>Mike,
> >>
> >>As the ChangeLog says, I updated the markers support on 9/25/2007 to 
> >>work with Mathieu's 9/18/2007 markers patch.
> >
> >
> >Sorry, I missed the ChangeLog entries.
> >
> >>
> >>So, are you using a version of systemtap that has those changes present? 
> >
> >
> >Yes, I'm using the latest cvs code.
> >
> >> Which version of Mathieu's markers patch are you using?
> >>
> >
> >I'm using the latest marker patches posted on 9/28.
> >
> >Thanks,
> >Mike
> >
>   
> 

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68