Building for multiple x86_64 micro-architectures simultaneously (x86_64, x86_64_v2, and x86_64_v3)

[Conan-Kudo]

For some time now, RPM has supported the architecture levels of x86_64 as distinct micro-architectures: x86_64, x86_64_v2, and x86_64_v3.

I would like for ELN to be the place where we figure out making it possible to build for multiple x86_64 micro-architectures simultaneously. There is significant community interest in this, to the point that there's a community contribution to make this work in DNF. There's interest for Fedora offering builds for x86_64 and x86_64_v3 similar to distributions like Arch Linux.

This also opens the door to stop having RHEL lie about its architecture: future RHEL using the x86_64_v3 architecture properly to denote its usage of this architecture level makes it much more clear and obvious what is going on.

[Conan-Kudo]

FYI: @lleyton in case you want to add more color here.

[yselkowitz]

Koji would have to play a big part in this, how is its support for such?

[Conan-Kudo]

It needs some trivial enhancements to support all subarches. There's support for v2 already: https://pagure.io/koji/pull-request/4416#

[yselkowitz]

And what about pungi?

[Conan-Kudo]

Pungi needs porting to DNF5. It still uses DNF4.

[fweimer-rh]

Can we move this to a different Fedora variant?

It does not make sense for ELN to drift further and further away from future RHEL.