Re: Detecting hard float/version in pkgsrc

[Martin Husemann <martin%duskware.de@localhost>]

On Sun, Jul 24, 2016 at 01:37:53PM +0000, coypu%SDF.ORG@localhost wrote:
> We could theoretically let users use ./bootstrap -native for those, put
> in devel/cpuflags, too...

Devel/cpuflags is a good way around one part of this for locally build
pkgs. It has the bonus that you can manually adjust the settings if your
build machine is different.

It does not work well for officially provided binaries, where it will be
hard to agree on a proper non-worst-case default. However, especially
on ARM we do really want different binaries for various families, and
I think we are trying to provide a good set of defaults for those already.

The other option is runtime selection, ideally based on sysctl variables
we provide reflecting the available cpu features, e.g.

machdep.sse = 1
machdep.sse2 = 1

on x86 or

machdep.fpu_present = 0
machdep.hwdiv_present = 0
machdep.neon_present = 0
machdep.simd_present = 0
machdep.simdex_present = 0

on arm.

This, of course, can only be patched per pkg and needs to be upstreamed.

Martin