Fedora delays x86-64-v3 optimized packages to version 46 — here's why

The Fedora Engineering and Steering Committee (FESCo) has rejected a proposal to introduce x86-64-v3 optimized packages for Fedora 45, pushing the plan back to at least Fedora 46. The committee will allow the change to be resubmitted for the next version, provided that the proponents supply additional performance data and clarify how installation media would be handled.

The proposal, which had been under discussion for several months, aimed to build Fedora packages using the x86-64-v3 microarchitecture feature level. This instruction set includes AVX/AVX2, FMA, BMI2, MOVBE, XSAVE, and other capabilities. It is supported by Intel processors from Haswell onward and AMD processors from Excavator onward — essentially covering nearly all consumer and server CPUs released over the past decade. The plan also included retaining x86-64-v1 packages for users with older hardware.

The move was of particular interest to Microsoft, whose Azure Linux distribution is built on top of Fedora. The company has expressed a desire to adopt x86-64-v3 as a baseline for its own purposes, citing performance gains from the newer instruction set.

FESCo's decision to reject the change for Fedora 45 came after months of debate and requests for more performance benchmarks. The committee wants to see concrete data demonstrating the real-world benefits of switching to x86-64-v3 across the entire distribution. They also seek details on how the installation media would be handled — for example, whether users would need to choose between x86-64-v1 and x86-64-v3 versions at download time, or if the installer would automatically detect the CPU capabilities.

The delay is noteworthy because some other Linux distributions have already made the jump. Red Hat Enterprise Linux 10, for instance, requires x86-64-v3 as a default, arguing that the instruction set covers virtually all Intel and AMD systems from the past decade. Fedora, being a community-driven distribution with a broader user base including those on older hardware, has taken a more cautious approach.

The rejection means that Fedora 45, which is expected to be released later this year, will ship without x86-64-v3 optimized packages. The discussion will resume in 2024 as part of the planning for Fedora 46, with the hope that the additional performance data will convince FESCo to approve the change. If approved, Fedora 46 could become the first Fedora release to offer both x86-64-v1 and x86-64-v3 package sets, giving users a choice between maximum compatibility and maximum performance.