Bug in configure script for PPC64 machines

[Fuzzy Logic]

I'm running a 2.6.5 64-bit kernel.

./try mpn_mul_1
*** glibc detected *** double free or corruption (out): 0x0ffbad90 ***
Segmentation fault

Is this the failure you were expecting to see?

Fuzzy

On 19 Feb 2007 17:10:52 +0100, Torbjorn Granlund wrote:

> If you too get spurious FAILs, then I think I might have figured out a
> possible explanation.
>
> Back in 2005, I isolated a problem with randomly clobbered registers
> under the Linux kernel when running binaries for the 32-bit but using
> the full powerpc64 instruction set.
>
> I don't run GNU/Linux on any ppc64 machines I have control over, so I
> cannot determine which kernels have this bug, even if I had the time
> and enjoyed building Linux kernels.
>
> I know the bug is in (Debian's version of) 2.6.11.
>
> You can check if this is indeed the problem you're running into by
> going into test/devel and then do,
>
>   make try
>   ./try mpn_mul_1
>
> If that fails randomly, i.e. after a varying number of iterations,
> you've almost certainly run into the kernel bug.
>
> I reported this back in June 2005.
>
> Some people might think configure should disable ppc64 instructions
> when it detects a Linux kernel.  I suppose that would be a good thing,
> at least if one can tell which kernels have the bug and which ones
> don't.
>
> Disabling important features in GMP to work around bugs in kernels and
> compilers is in general a bad idea, unless it is disabled just for
> problem kernels and compilers.  If we do it too broadly, we'll end up
> with an empty envelope before long.