[CentOS-devel] ISA SIG rebuild status

Wed Jun 28 17:13:25 UTC 2023
Florian Weimer <fweimer at redhat.com>

* Ali Erdinc Koroglu:

> I'm gonna submit a change proposal to replace zlib to zlib-ng for F41
> or F42 but I don't think that even CentOS Stream 11 or RHEL11 can use
> that.  So what I'm offering is since we did not brake any API/ABI in
> Zlib, AVX2 deflate optimization applicable for CentOS ISA SIG
> x86-64-v3

I think zlib-ng has a build mode that is supposed to be ABI-compatible.
We have plans to evaluate that at Red Hat.  If it's indeed compatible,
we can just swap it out in a Fedora release and consider what to do
next.

We currently carry some zlib patches with architecture-specific
optimizations, but the original upstream is not willing to take those
patches, and the various downstream patches cause maintenance issues.
The presence of IFUNC resolvers introduces crashes into some third-party
applications because these symbols are frequently interposed, causing
relocation ordering problems.

Thanks,
Florian