Re: disable avx instructions at runtime

[Mike Frysinger <vapier at gentoo dot org>]

On Sunday 10 March 2013 17:35:29 Tim Blechmann wrote:
> >> i'm using a debugger, that does not support avx instructions (at least
> >> the back-in-time functionality doesn't). unfortunately, glibc/libm uses
> >> some sort of runtime dispatching to provide an avx-implementation for
> >> mathematical functions like sin or cos.
> > 
> > yes, it uses cpuid to detect support.  there were bugs though in the
> > implementation in older releases that caused it to get used when it
> > shouldn't. try using glibc-2.17.
> 
> it is a bit tricky: my debugger provides a replay engine, which prbly
> maps cpuid to the physical instruction

sounds like your replay engine is broken then.  i don't understand why people 
don't just fix the source of the problem.  valgrind had a similar issue -- it 
didn't properly emulate cpuid, so people requested we disable things in glibc 
instead of updating valgrind.
-mike

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