The RVA23 profile, ratified in October 2024, defines a mandatory baseline of 33 U-mode and 25 S-mode extensions. During the upstream enablement of SpacemiT K3, I identified gaps in the kernel's RVA23 extension coverage and submitted patches to address them. After several revision cycles, the patches were merged into Linux v7.0, raising coverage from 69% to 100%.

This talk will examine how the Linux kernel community approaches RISC-V extension support - the design principles behind accepting new extensions into the kernel, and how the maintainers manage the growing complexity of the RISC-V extension landscape.

I will then present two patchsets currently under review for Linux v7.1: my series adding cpufeature parsing and hwprobe export for RVA23 extensions, and Andrew Jones' (Qualcomm) RFC introducing rva23u64 base behavior detection. I will discuss the key architectural decisions in these patches, the review feedback received, and the current status.

Depending on the upstream timeline, these may already be merged by the Summit, or still in progress - either way, the talk will reflect the latest state of the kernel community's work.

Achieving complete RVA23 support in mainline Linux is a prerequisite for distributions to ship generic RISC-V images that work across compliant hardware, reducing fragmentation. We hope to invite RISC-V kernel community members at the Summit for an open discussion on remaining challenges and future profile evolution.