[ltt-dev] no metadata tracefile

[Mathieu Desnoyers]

* Alex Luccisano (luccisa) (luccisa at cisco.com) wrote:
> Hi Mathieu,
> 
> > -----Original Message-----
> > From: Mathieu Desnoyers [mailto:compudj at krystal.dyndns.org]
> > Sent: Thursday, September 22, 2011 09:36
> > To: Ji Zhai
> > Cc: ltt-dev at lists.casi.polymtl.ca
> > Subject: Re: [ltt-dev] no metadata tracefile
> > 
> > * Ji Zhai (Ji.Zhai at ca.flextronics.com) wrote:
> > > Hi Mathieu,
> > >
> > > I'd like to know if you have had time to review my question. If
> > > possible, can you please give me a guide/direction to debug this
> > > issure?
> > 
> > Hi Ji,
> > 
> > Sorry, I am pretty busy on UST 2.0 these days.
> > 
> > About your question you might want to try adding "printf" statements
> > within marker.c in UST, and also try compiling UST with -DUST_DEBUG=1
> so
> > enable debugging output. I fear there is a linker issue on your
> system,
> > but unfortunately I don't have access to your setup.
> > 
> > Try comparing the outputs of a simple test program in your powerpc
> > target setup, in a native host x86 setup, and in a native host x86_64
> > setup. This way you should be able to identify what is missing.
> 
> [AL:] I've been helping with this effort and what you describe above is
> exactly what I did here:
> 
> http://lists.casi.polymtl.ca/pipermail/ltt-dev/2011-September/005135.htm
> l
> 
> There seems to be some problem with __start__ust_marker_ptrs.  How
> should this be linked with the "foo" binary?

In UST 0.x, linking libust-initializer.o with the executable is supposed
to take care of this. It uses the __start/__stop automatic linker
symbols for this.

Some info on this here:

http://www.airs.com/blog/archives/56

It would be interesting to find out why on powerpc this linking does not
seem to be done. Printing the values of those symbols in a constructor
might help understanding what is going on there. Maybe try removing
__attribute__((visibility("hidden"))) from the extern declarations at
the top of marker.c ? Also try adding:

UST_MARKER_LIB;

to your application C file (and don't link with libust-initializer.o
this time) to see if this helps.

Please note that this whole libust-initializer.o scheme is going away
for ust 2.0.

Thanks,

Mathieu

> 
> Regards,
> Alex
> 
> > 
> > Best regards,
> > 
> > Mathieu
> 

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com