Re: Systemtap scripts unable to compile on RHEL4 U2

Re: Systemtap scripts unable to compile on RHEL4 U2

[Frank Ch. Eigler]

Hi -

wcohen wrote:

> [...] SystemTap should be a bit more vocal when it is unable to find
> any debuginfo for the kernel being instrumented [...]

That's true.  At one point, it used to say so.


parasadav wrote:

> 1) Is it not a good idea as part of the very first check translator
> can do a version check between the debug info it is using and the
> version of the binary where it is going to insert probes?

While such a check would be prudent, at the moment it will never fail,
as systemtap/elfutils can select only the debuginfo for the currently
running kernel version/release.  It doesn't matter if other debuginfo
versions are installed - they won't be looked at.  (But see bug
#1145.)

> 2) If a customer upgrades the OS release how do we make sure the
> corresponding debug info matches without corresponding debug RPM's
> shipped.

We can't make sure of such a thing.  Users will need to update their
debuginfo's along with their kernels.  Users of RH packages may wish
to subscribe to this bug, until debuginfo distribution problems are
solved: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=139767


- FChE

RE: Systemtap scripts unable to compile on RHEL4 U2

[Keshavamurthy, Anil S]

Please see my comments below.

-Anil

>systemtap-owner@sources.redhat.com wrote on 2005-09-27 05:30:48:
>
>> Hi,
>>    I did a full install of the latest and greatest RHEL4
>> U2(2.6.9-20.ELsmp) 
>> on x86_64 box. Trying to compile a simple tap script and 
>seeing errors.
>> 
>> Parsed 'do_fork' -> func 'do_fork'
>> Semantic error: no match for probe point
>>    while: resolving probe point kernel.function("do_fork");
>> Pass 2: analysis failed. Try again ......
>> 
>> 
>> Am I missing anything here? Does this have any dependencies on
>> kernel-debuginfo RPM?
>> Also I did not find kernel-debuginfo RPM on RHEL4 U2 Beta CD's.
>> 
>
>You need kernel-debuginfo RPM.
>
>You can download the kernel src RPM package from 
>rhn.redhat.com, and then:
>  1. install the rpm package
>  2. build the rpm src package:  #cd /usr/src/redhat; rpmbuild -ba 
>SPECS/kernel-2.6.spec --target=x86_64
>    to save your time, you can edit 
>/usr/src/redhat/SPECS/kernel-2.6.spec 
>to comment one or more of the following defines:
>                #define buildup 0
>                #define buildsmp 1
>                #define buildsource 0
>                #define buildhugemem 0
>                #define builddoc 0
>                #define kabi 1
>   finally, rpmbuild will generate kernel-debuginfo, kernel, 
>kernel-devel 
>RPMs in /usr/src/redhat/RPMS/x86_64
>

The above procedure is okay for the developers, but not advisable for
end users I think.
If Systemtap RPM is installed then all its dependencies should be met
else I think there is some 
bug and people get confused.

Re: Systemtap scripts unable to compile on RHEL4 U2

[William Cohen]

Keshavamurthy, Anil S wrote:

<...>

> The above procedure is okay for the developers, but not advisable for
> end users I think.
> If Systemtap RPM is installed then all its dependencies should be met
> else I think there is some 
> bug and people get confused.

Having a dependency on kernel-debuginfo is not going to work. It breaks 
the way that the distribution set of rpms is computed. Red Hat doesn't 
currently ship the kernel-debuginfo.

Also there is no guarantee that the kernel-debuginfo installed is the 
one for the kernel being instrumented. It is quite possible to get 
messages saying "no match for probe point" even with a kernel-debuginfo 
installed if it doesn't match the kernel being instrumented.

SystemTap should be a bit more vocal when it is unable to find any 
debuginfo for the kernel being instrumented, rather than having the 
developer determine whether the debug information is missing or whether 
the developer mis-typed the function name.

-Will

Re: Systemtap scripts unable to compile on RHEL4 U2

[Vara Prasad]

William Cohen wrote:

> Keshavamurthy, Anil S wrote:
>
> <...>
>
>> The above procedure is okay for the developers, but not advisable for
>> end users I think.
>> If Systemtap RPM is installed then all its dependencies should be met
>> else I think there is some bug and people get confused.
>
>
> Having a dependency on kernel-debuginfo is not going to work. It 
> breaks the way that the distribution set of rpms is computed. Red Hat 
> doesn't currently ship the kernel-debuginfo.
>
> Also there is no guarantee that the kernel-debuginfo installed is the 
> one for the kernel being instrumented. It is quite possible to get 
> messages saying "no match for probe point" even with a 
> kernel-debuginfo installed if it doesn't match the kernel being 
> instrumented.
>
> SystemTap should be a bit more vocal when it is unable to find any 
> debuginfo for the kernel being instrumented, rather than having the 
> developer determine whether the debug information is missing or 
> whether the developer mis-typed the function name.
>
> -Will
>
This brings up couple of questions.

1) Is it not a good idea as part of the very first check translator can 
do a version check between the debug info it is using and the version of 
the binary where it is going to insert probes?

2) If a customer upgrades the OS release how do we make sure the 
corresponding debug info matches without corresponding debug RPM's shipped.

RE: Systemtap scripts unable to compile on RHEL4 U2

[Keshavamurthy, Anil S]

>I can make a copy informally available for
>download in a couple of hours.

I am using RHEL4 U2  on x86_64 with the kernel version 2.6.9-20.Elsmp,
Don't worry, I will build the debug kernel myself as I have the kernel
sources with me.

-thanks,
Anil

Systemtap scripts unable to compile on RHEL4 U2

[Keshavamurthy, Anil S]

Hi,
	I did a full install of the latest and greatest RHEL4
U2(2.6.9-20.ELsmp) 
on x86_64 box. Trying to compile a simple tap script and seeing errors.

Parsed 'do_fork' -> func 'do_fork'
Semantic error: no match for probe point
	while: resolving probe point kernel.function("do_fork");
Pass 2: analysis failed. Try again ......


Am I missing anything here? Does this have any dependencies on
kernel-debuginfo RPM?
Also I did not find kernel-debuginfo RPM on RHEL4 U2 Beta CD's.


Any help is highly appreciated.

Thanks,

-Anil Keshavamurthy
Sr. Software Engineer
Open Source Technology Center/SSG
Intel Corp.
(w) 503-712-4476

Re: Systemtap scripts unable to compile on RHEL4 U2

[Frank Ch. Eigler]

"Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> writes:

> [...]
> Am I missing anything here? Does this have any dependencies on
> kernel-debuginfo RPM?

Yes.  Our release engineering folks requested that we remove the
explicit "kernel-debuginfo" dependency within the RPM.  Nevertheless,
you need it to make probes like yours work.

> Also I did not find kernel-debuginfo RPM on RHEL4 U2 Beta CD's.

Unfortunately, we're still trying to work out how best to distribute
these rather bulky files.  If you tell me your exact kernel
version/architecture, I can make a copy informally available for
download in a couple of hours.

- FChE

Re: Systemtap scripts unable to compile on RHEL4 U2

[Guang Lei Li]

systemtap-owner@sources.redhat.com wrote on 2005-09-27 05:30:48:

> Hi,
>    I did a full install of the latest and greatest RHEL4
> U2(2.6.9-20.ELsmp) 
> on x86_64 box. Trying to compile a simple tap script and seeing errors.
> 
> Parsed 'do_fork' -> func 'do_fork'
> Semantic error: no match for probe point
>    while: resolving probe point kernel.function("do_fork");
> Pass 2: analysis failed. Try again ......
> 
> 
> Am I missing anything here? Does this have any dependencies on
> kernel-debuginfo RPM?
> Also I did not find kernel-debuginfo RPM on RHEL4 U2 Beta CD's.
> 

You need kernel-debuginfo RPM.

You can download the kernel src RPM package from rhn.redhat.com, and then:
  1. install the rpm package
  2. build the rpm src package:  #cd /usr/src/redhat; rpmbuild -ba 
SPECS/kernel-2.6.spec --target=x86_64
    to save your time, you can edit /usr/src/redhat/SPECS/kernel-2.6.spec 
to comment one or more of the following defines:
                #define buildup 0
                #define buildsmp 1
                #define buildsource 0
                #define buildhugemem 0
                #define builddoc 0
                #define kabi 1
   finally, rpmbuild will generate kernel-debuginfo, kernel, kernel-devel 
RPMs in /usr/src/redhat/RPMS/x86_64

> 
> Any help is highly appreciated.
> 
> Thanks,
> 
> -Anil Keshavamurthy
> Sr. Software Engineer
> Open Source Technology Center/SSG
> Intel Corp.
> (w) 503-712-4476