[mythtv] Mixed debug/release build

Daniel Kristjansson danielk at cuymedia.net
Sat Aug 25 15:45:12 UTC 2007

On Sat, 2007-08-25 at 13:05 +0200, Michael Haas wrote:
> Daniel Kristjansson wrote:
I'll take this as a vote in favor of #3589, with the recognition
that it may require changes in how the packages are built.

> Our packages are built with "--compile-type=debug --tune=i486
> --enable-proc-opt" (please don't ask me why we --tune=i486, I never
> understood that myself).
Tune i486 is probably based on wanting the 10% speedup of cmov that
i486 has over i386, but still wanting to work on most Intel/AMD CPUs.
MMX and SSE can give a significant boost as well, but I'm not sure
how these options will be handled by configure, tune and enable-proc-opt
are not meant to be used together.

>  Our backtraces were rejected (eg
> <http://svn.mythtv.org/trac/ticket/3561#comment:1>) and I was told that
> the optimizations were breaking them. However, it just dawned on me that
> "--enable-proc-opt" enables "-fomit-frame-pointer". Gah! That was
> probably the cause for bad backtraces... anyways, -O3 was also lined out
> to be a bad thing.
> That's the whole point - the Ubuntu packages *could* already be profile
> builds with the debug symbols stripped and put in separate .ddebs.
> However, you're the first one to tell me that such backtraces would be
> accepted. If that's true, I'm not sure if my patch is still needed.

This depends, while an optimized build can be debugged, it results in
non useful backtraces more often than non-optimized builds. This means
we need the users help to diagnose the problem. Tickets in our trac
are generated by users so we assume we will be able to get that help.
With automatically generated reports we don't have that help so they
should really go in a separate trac, where we just close tickets
without the overhead of describing why the backtrace is not useful.

Having full debugging on all the portions of MythTV that don't need to
be super optimized would make the backtraces more useful so I think this
change may be important. Can you add the patch to the #3589 ticket and
explain what it does (you can copy your initial e-mail)?

-- Daniel

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