RISC-V Extensions update including 29 extensions to stabilize #1987
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Possible ConsiderationSome platform behavior extensions are hard to make a short, concise summary. Do we prefer to keep long(er than usual) descriptions? Or, do we just link to the RISC-V Profiles documentation and let it explain? My Current PositionI prefer the latter if allowed but mdbook design is confirmed not broken so the current approach (long descriptions) is okay for me. |
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Ping. Can someone review this PR? |
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The `Zb` extension does not exist and we instead have the `B` extension which is a superset of the three subextensions: `Zba`, `Zbb` and `Zbs`. For now (since `B` extension is not stabilized on Rust), this commit just removes `Zb`.
This is the latest ratified ISA Manual version and more importantly, some individual documents are merged into this. So, this commit consistently use this Manual (this version) where possible. Along with this, this commit substitutes link IDs from `rv-zb-*` to `rv-*` because `rv-zb-*` will look like the different document (bit-manipulation) is referenced.
rust-lang/rust#140139 changed the target feature implication without updating the Reference. That change is came from the fact that the Zbc extension is a functional superset of the Zbkc extension. This commit fixes this issue. Appendix - List of all Zbkc / Zbc instructions: * `clmul` (Zbkc / Zbc) * `clmulh` (Zbkc / Zbc) * `clmulr` (Zbc only)
This commit directly corresponds to rust-lang/rust#145948. References: 1. RISC-V Instruction Set Manual (version 20250508): <https://github.com/riscv/riscv-isa-manual/tree/20250508> 2. RISC-V Profiles (version 1.0 - RVA23 is not stabilized at the time): <https://github.com/riscv/riscv-profiles/tree/v1.0> 3. RISC-V Profiles (RVA23/RVB23-ratified version): <https://github.com/riscv/riscv-profiles/tree/rva23-rvb23-ratified>
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Amanieu
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Sep 18, 2025
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This PR directly corresponds to rust-lang/rust#145948 (and this is a superset of #2002).