Status of kernel marker support

Status of kernel marker support

[Mike Mason]

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

Re: Status of kernel marker support

[David Smith]

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.

So, are you using a version of systemtap that has those changes present? 
  Which version of Mathieu's markers patch are you using?

-- 
David Smith
dsmith@redhat.com
Red Hat
http://www.redhat.com
256.217.0141 (direct)
256.837.0057 (fax)

Re: Status of kernel marker support

[Mike Mason]

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

Re: Status of kernel marker support

[David Smith]

Mike Mason wrote:
> David Smith wrote:
>> Mike Mason wrote:
>>  Which version of Mathieu's markers patch are you using?
> 
> I'm using the latest marker patches posted on 9/28.

I'll try to see if I can update the systemtap marker code to handle the 
9/28 patches.

-- 
David Smith
dsmith@redhat.com
Red Hat
http://www.redhat.com
256.217.0141 (direct)
256.837.0057 (fax)

Re: Status of kernel marker support

[Vara Prasad]

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

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
>
   

Re: Status of kernel marker support

[Vara Prasad]

Vara Prasad 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.

I meant we are trying to exploit markers infrastructure patch and add 
markers in the kernel.

> Are we using the latest version of the markers patch or do you have 
> more updated versions?
> If we find bugs while using markers can we open them in the SystemTap 
> bugzilla?
>
> 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
>>
>  

Re: Status of kernel marker support

[Randy Dunlap]

On Tue, 02 Oct 2007 12:33:38 -0700 Vara Prasad 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?

The 9/28 patch series that Mike referred to is the latest,
and Andrew Morton wrote that he plans to merge it into
2.6.24 (2.6.23 will probably be final soon, in a few days).


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

If you want to report mainline kernel bugs, they should go into
bugzilla.kernel.org IMO.


> 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

---
~Randy

Re: Status of kernel marker support

[Mathieu Desnoyers]

* 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

Re: Status of kernel marker support

[David Smith]

Mathieu Desnoyers wrote:

> 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

Thanks for the tarball - I've been downloading the patches from a lkml 
web archive today and there were a bit mangled so this will help.

> 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.

I figured the removal of the __markers_string section was coming, so 
I've been trying to look into this.

I've certainly seen that distinction in the 9/18 patch set - the main 
kernel has the __markers section packed in the .data section (surrounded 
by __start___markers and __stop___markers) but kernel modules have a 
distinct __markers section.

Out of curiosity, was there a particular reason for the two different 
methods or did it just work out that way?

-- 
David Smith
dsmith@redhat.com
Red Hat
http://www.redhat.com
256.217.0141 (direct)
256.837.0057 (fax)

Re: Status of kernel marker support

[Mathieu Desnoyers]

* David Smith (dsmith@redhat.com) wrote:
> Mathieu Desnoyers wrote:
> 
> >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
> 
> Thanks for the tarball - I've been downloading the patches from a lkml 
> web archive today and there were a bit mangled so this will help.
> 

The mangling comes from the checkpatch.pl fixes Andrew added to his own
tree. If you want the, you would have to dig into the mm-commits mailing
list.

> >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.
> 
> I figured the removal of the __markers_string section was coming, so 
> I've been trying to look into this.
> 
> I've certainly seen that distinction in the 9/18 patch set - the main 
> kernel has the __markers section packed in the .data section (surrounded 
> by __start___markers and __stop___markers) but kernel modules have a 
> distinct __markers section.
> 
> Out of curiosity, was there a particular reason for the two different 
> methods or did it just work out that way?
> 

In the kernel, we don't "need" the markers section, because all we care
about is to get symbols pointing to the beginning and the end of the
section. For the modules, however, we need to have a distinct section
because we have to get pointers to the beginning of the section and get
the section size in load_module() (using find_sec). So, basically, yes,
it worked out that way. And yes, it is heavily inspired of the way other
sections are dealt with in the kernel and in load_module(). :)

Mathieu

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