On Mon, 1 Feb 2016 20:05:11 +0000
Ken Moffat <zarniwh...@ntlworld.com> wrote:
> The only hardware-specific thing I recall "recently" was gmp - since
> September 2015 I have been using the configfsf.{guess,sub} over the
> config. versions. Discussed on the lfs-dev list back then.
Yeah, I sure do remember that ordeal as I participated in it:
https://www.mail-archive.com/blfs-support@lists.linuxfromscratch.org/msg02166.html
and as the thread went on we finally tracked down the specific
illegal instruction.
The offender turned out to be the mulx instruction:
https://www.mail-archive.com/blfs-support@lists.linuxfromscratch.org/msg02228.html
and therein is a patch for the gmp source to lockout the use of bmi2
instruction set (of which mulx is one).
Also, note from my post a way to check to see if a CPU supports
the bmi2 instruction set:
: cat /proc/cpuinfo
:
: To support mulx, the CPU must list bmi2 in the cpuinfo flags section:
:
:
http://unix.stackexchange.com/questions/43539/what-do-the-flags-in-proc-cpuinfo-mean
:
: (see under "Intel-defined CPU features, CPUID level 0x00000007:0 (ebx)")
In this way, Edgar can compare the CPUs of his two machines. I bet they
differ with regard to bmi2 capability.
Cheers,
Mike Shell
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