GMP doesn't honor march flag

[Paul Jähne]

Hello Torbjörn,

I wasn't aware that GMP uses config.guess to set the architecture. 
Adding --build=westmere-pc-linux-gnu solved the issue.

Thanks for the hint.

Paul

Am 21.12.2017 um 11:17 schrieb Torbjörn Granlund:
> Paul Jähne <paul.jaehne at gmx.de> writes:
>
>    I encountered a problem with GMP when using the march flag.
>    
>    I build GMP 6.1.1 with march=corei7 or march=westmere with GCC 5.4.0
>    on a server with a Haswell processor (E5-2630 v3). When executing curl
>    (version 7.47.0 on Ubuntu 16.04) which uses GMP to retrieve a https
>    website on a system with a Westmere Processor (Intel Xeon E5645) it
>    crashes with the error: Illegal instruction (core dumped).
>    
> No GMP bug.  You're not following the doumented procedures.  Don't
> override CFLAGS like that, it is ineffective and as you omitted any -O
> also a disaster for performance.
>
> You might find it helpful to read the GMP manual's chapter "Installing
> GMP".  There are many good suggestions there!
>
>