[CentOS-devel] glibc-2.28-145.el8 with glibc-hwcaps support is coming to CentOS Stream 8

Fri Jan 8 09:15:06 UTC 2021
Florian Weimer <fweimer at redhat.com>

* Fabian Arrotin:

> Thanks a lot for the announce, really appreciated to be aware of what's
> coming .
> I'd (myself) like to see some kind of announces being sent on the public
> list so that everybody can follow what's being worked on and so what to
> expect in Stream packages (as of course there is no official public
> Release Notes -yet- , appearing for RHEL, so downstream)

I'm going to let others comment on that.

> Now back to the x86 cpu infra : does that mean that to *build* Stream
> packages (like gblic) we need at least a minimum instructions set in the
> CPU (builder side that is) ?

glibc itself continues to use IFUNCs on x86-64 to select optimized
function implementations, based on CPU capabilities.  This means that
baseline x86-64 support remains sufficient for building the glibc
package.

I can image that in the future, there will be some packages which build
shared objects for x86-64-v3 (in addition to baseline x86-64, with
run-time selection later), and which test all implementations at build
time.  In such a scenario, the builders would have to support x86-64-v3.

In related news, we plan to build CentOS Stream 9 with a x86-64-v2
baseline:

  Building Red Hat Enterprise Linux 9 for the x86-64-v2 microarchitecture level
  <https://developers.redhat.com/blog/2021/01/05/building-red-hat-enterprise-linux-9-for-the-x86-64-v2-microarchitecture-level/>

Thanks,
Florian
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