[petsc-dev] error with flags PETSc uses for determining AVX

[Jed Brown]

Pierre Jolivet <pierre at joliv.et> writes:

> I’m playing the Devil’s advocate since the beginning, we’ve had a --enable-generic (off by default) which turns -march=native into -march=generic for 20+ years (I’m seeing references to PPC7450 and Intel Coppermine in our configure…).
> We turn this flag on when building our .exe/.pkg/.deb.
> I just think you’ll have to find a very very efficient way to advertise this change, because let’s face it, very few people outside of upstream developers read the changelog, and so people may start bundling up PETSc without this additional flag, and could potentially get spammed by end-users having a hard time figuring out why they get illegal instruction errors.
> On some occasions we have such a message, but PETSc stands much lower in the software stack than our library so it’s likely it's bundled (instead of used on the same architecture as the compile node) way more often, IMHO (I guess you know the figure better than me…).

I'm not opposed to an -march=native default, but configure should be loud about it and we should be proactive about contacting all the packagers we know of.