RHEL9 Likely To Drop Older x86_64 CPUs, Fedora Can Better Prepare With "Enterprise Linux Next"

Red Hat Enterprise Linux 9 will likely see support for older x86_64 CPUs eliminated to focus on more modern x86_64 Intel/AMD families. With that, Red Hat developers working on Fedora have been working on an "Enterprise Linux Next" proposal to not only vet such x86_64 build changes but also to provide a feedback workflow for other changes.

Brought up last month already was an extra buildroot for testing x86_64 microarchitecture updates on Fedora. Currently, Fedora and RHEL support x86_64 CPUs going back to the original AMD K8 CPUs but with RHEL9 some middle-ground will likely be pursued of aiming to support more recent x86_64 families and newer instruction set extensions by default while still supporting a diverse enough range of hardware to be in production use-cases during RHEL9's life-cycle.

This follows last year's discussion over potentially raising Fedora's CPU requirements to AVX2-enabled processors. The AVX2 requirement was shot down for now but does raise the possibility that is the threshold Red Hat engineers are looking at as a potential base requirement for Red Hat Enterprise Linux 9. AVX2 is found on Intel Haswell CPUs (2013) and newer or AMD Excavator CPUs (2015) and newer.

Proposed this week as an extension of that x86_64 buildroot testing is an ELN builtroot and compose setup. This "Enterprise Linux Next" (ELN) feature is to provide a feedback loop for Fedora developers on the status of package builds and image composes in a manner resembling the CentOS/RHEL build process.

The Fedora ELN setup would consist of a buildroot configuration, RPM flags, and other configurations to offer a more similar process to the CentOS/RHEL build handling. The discussion over the ELN proposal can be found on the Fedora mailing list. The Fedora Engineering and Steering Committee still needs to evaluate the proposal.

On the x86_64 support threshold for the next major RHEL release, it will be interesting to see what is decided. Given the past RHEL cycles, Red Hat Enterprise Linux 9 probably won't be out until at least 2023. By that time RHEL9 ships it may be quite reasonable for using AVX2 as a base requirement for RHEL and Fedora. Raising the base requirement will certainly help in allowing more modern compiler flag defaults to juice measurably more performance out of the system for many workloads compared to the current AMD K8 default.