[ltt-dev] gdb-7.2 can't build with lttng-ust-0.12

[compudj@krystal.dyndns.org (Mathieu Desnoyers)]

* Cui, Dexuan (dexuan.cui at intel.com) wrote:
> Due to the API changes in lttng-ust 0.12,  gdb's latest version 7.2 can't build with lttng-ust:
> http://sourceware.org/ml/gdb/2011-04/msg00140.html
> 
> Hope somebody here can help gdb to work with ust 0.12. :-)

Hi Dexuan,

We're currently doing instrumentation API changes in UST. At the moment,
it is in the git tree, planned for release in UST 0.13. Our goal is to
perform this painful (but required) step sooner than later so that we
minimize the amount of pain for our user-base.

Also, we should reopen the discussion on the way the UST Markers collect
the registers for GDB, because the current way involves a _lot_ of ugly
assembly code. It should be possible to only use a volatile inline asm
to specify input constraints on the target marker parameters, and keep
the instruction pointer address that corresponds to this inline asm in a
section known by gdb (so gdb could use the drawf info to fetch data from
registers/memory). If you can ensure that this would fit gdb's
requirements, I could clean up the marker code and we could resync the
APIs together. We could also provide this for UST Tracepoints in the
same go, with pretty much the same interface as we'd use for UST
Markers. I am aware that this would require change on the GDB side, but
I think it's better to synchronise our effort rather than to shoot at
different targets.

Thanks,

Mathieu

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