Re: Kernel handling of vector registers
On Thu, 2006-02-23 at 15:42 +0100, Torbjorn Granlund wrote:
> I recently committed several GMP assembly functions for powerpc32
> using Altivec registers and instructions.
>
> I also reinstalled my system (a Pegasos2) recently, from an obsolete
> snapshot I got from somebody on the net, to a much less obsolete
> system.
>
> With the new assembly code *and* with the new GNU/Linux installation,
> the system fails intermittently in GMP's make check. I don't know how
> to debug such an intermittent failure.
>
> The same GMP code works correctly on Mac OS X.
>
> Debugging such an intermittent problem is close to impossible.
>
> Do you know if the Linux kernel correctly handles Altivec registers
> during context switch? Does it require setting the VRSAVE special
> register, BTW? (I set it properly, since Mac OS X needs it, and
> setting it shouldn't hurt.)
>
> (The kernel on the system identifies itself as 2.6.12.)
It should but there have been bugs in the past, notably with signals.
You may want to try with a more recent kernel.
Ben.
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