ROCM host architectures

[Christian Kastner <ckk@debian.org>]

Dear ROCm Team,

the builds for the recent rocr-runtime [1] failed on all 32-bit
architectures, and rocm-hipamd [2] only succeeded on amd64 and arm64. I
assume this will be the case for many other related packages.

This is hardly surprising, as some of these architectures (most notably
armel, armhf, mipsel, i386) are probably not at all what ROCm was
intended for. For example, it seems that PCIe 3.0 with atomics are
required for anything GPU-related.

Some of these packages present quite a burden to the buildds of these
already very constrained systems.

I propose that unless we expect this builds to pass and the packages to
also be usable, we should initially limit to:

    Architecture: amd64 arm64 ppc64el

For package buildds that already pass on architectures not listed above,
I'm somewhat skeptical that we'd want them in testing, if only for the
maintenance burden that they can cause (unusable or FTBFS -> RC).

I don't think the above would have any negative impact on actual users,
but on the positive side, would reduce the burden on the relevant
buildds, and possibly also on the maintainers.

Going forward, assuming that these packages will sooner or later all
have autopkgtests anyway, I would suggest that we extend the
architecture list as soon as we get the tests to pass.

Thoughts?

Best,
Christian