I am supposed to ask you about your opinion about how to ask buildsys to
build for specific archs for a kernel module. I believe that we should
use ExclusiveArch with explicit listed archs, and buildsys should loop
through each listed arch and build each. This would also work for
multi-arch performance intensive userspace packages similar to what we
do in glibc or openssl in Core.  Contributors may also list any
other arch like s390x or alpha in ExclusiveArch, and buildsys simply
ignores it if it isn't supported in Extras.
I believe this is the best approach to take for Extras, because Core has
been similar to this for many years. Do you have any opinion on this,
or know of a better way to handle this?
Here is some related discussion:
<scop> the problem with exclusivearch is that let's say you list i586
i686 x86_64 ppc and someone wants to rebuild it for alpha -> won't
build, even if the package/software would work
<warren> scop, you can include other archs in the list, buildsys can
simply ignore Extras non-supported archs.
<scop> warren, it's abuse of the tag nevertheless
<warren> scop, I'd personally disagree, but either way this is very
simple and it already behaves similar to this in Core literally forever.
<warren> more importantly the simplicity of this allows us to move
<warren> (assuming dcbw doesn't have a better idea)
<scop> that I agree with
However we should disallow this, unless someone proves through
benchmarks that there is a huge benefit of publishing both i386 and i686
packages and our tools support selection of the right arch directly.
Currently I believe it doesn't.