Changes/Power4kPageSize

POWER 4k page size

Summary

On ppc64le, the kernel is currently compiled for 64k page size.

This change proposes using the more common 4k page size.

Some HPC workloads may be disadvantaged slightly. Workstation users are likely to encounter fewer bugs.

Some things, like the AMD Radeon GPU drivers, firmware or related code, appear to be completely non-functional on the 64k page size. Insufficient upstream developers are testing such issues on this architecture.

Owner

• Name: Daniel Pocock
• Email: daniel@pocock.pro

Current status

• Targeted release: Fedora 34
• Last updated: 2021-01-11
• FESCo issue: <will be assigned by the Wrangler>
• Tracker bug: <will be assigned by the Wrangler>
• Release notes tracker: <will be assigned by the Wrangler>

Feedback

Discussed several times on devel, latest here

discussed upstream in the Raptor forum

Benefit to Fedora

Better first impression for users of ppc64le workstations.

Users can focus on reporting ppc64le bugs without being sidetracked by page size bugs.

Scope

• Proposal owners: DanielPocock

• Other developers: please volunteer by adding your name here

• Release engineering: #9939 (a check of an impact with Release Engineering is needed)

• Policies and guidelines: no, as it is an arch-specific issues, most other architectures already have a 4k page size

• Trademark approval: N/A (not needed for this Change)

• Alignment with Objectives: none of the current objectives relate to this change

Upgrade/compatibility impact

N/A (not a System Wide Change)

Dependencies

All RPMs must be rebuilt on a server running the final page size (4k)

Contingency Plan

• Contingency mechanism: Prepare a kernel with the original 64k config, install it on the build server, rebuild all the packages for this architecture
• Contingency deadline: whenever the last time for a full rebuild or kernel change is possible
• Blocks release? Yes, full rebuild of all packages must be completed before release
• Blocks product? product