RISC-V Extension Landscape

An interactive reference for RISC-V extensions, profiles, and per-instruction encodings. Pick a base ISA or start from a ratified profile, add extensions, and get a dependency-resolved configuration with a valid -march string.

Open the live site

• Browse every catalogued extension, grouped and searchable by name, mnemonic, or hex encoding.
• Build a configuration. Select extensions and dependencies resolve automatically, with conflicts blocked and a reason shown for every implied extension.
• Start from a profile. RVA23, RVB23 and the other ratified profiles load as a starting point rather than being rebuilt by hand.
• Export a -march string, a YAML configuration, or a riscv-config compatible file.
• Check an encoding. The Encoder Validator tests a proposed instruction pattern against every existing one and reports overlaps.
• Link out to the specification. Each extension links to its section on docs.riscv.org.

Node.js and npm are the only requirements.

npm ci
npm run build
python3 -m http.server 8080 -d dist

Then open http://localhost:8080.

Docker, if you prefer:

docker compose up --build

Three sources with different authority, which is worth knowing before changing anything:

riscv-unified-db is normative for dependencies. clang is the check that what we emit is actually usable: CI feeds every generated -march string to a real compiler. riscv-config, RISC-V International's own validator, disagrees with clang in a few places, and where it does both opinions are recorded rather than one being quietly preferred.

Regenerate with:

npm run sync          # instruction encodings from riscv-opcodes
npm run sync:udb      # extension metadata from riscv-unified-db
node scripts/seed-dependency-graph.mjs --udb <path-to-riscv-unified-db>
node scripts/map-doc-links.mjs                # documentation links

Or check for drift without writing anything:

npm run sync:check
npm run graph:check -- <path-to-riscv-unified-db>
npm run links:check

npm test        # 114 tests

CI runs the tests, builds, then validates every generated -march string against clang. The suite covers dependency closure, graph integrity, profile correctness, riscv-config conventions, export formats, documentation links, and a jsdom smoke test that fails if the page renders blank.

Add an entry to the appropriate group in src/riscv_extensions.json:

{
  "id": "Zfoo",
  "name": "Zfoo",
  "tags": ["rv_zfoo"],
  "desc": "Short description",
  "use": "What it enables",
  "url": "https://docs.riscv.org/reference/..."
}

• tags are riscv-opcodes extension names. Instruction membership is derived from them, so a wrong tag produces a wrong instruction count.
• url points at the extension's page on docs.riscv.org; npm run links:check verifies it resolves.
• discontinued: 1 adds the "Discontinued" badge.

Then add a graph node, or the tests fail:

node scripts/seed-dependency-graph.mjs --udb <path-to-riscv-unified-db>
npm test

Encodings live in src/instr_dict.json, keyed by the mnemonic lowercased with . replaced by _, so SC.W becomes sc_w:

"sc_w": {
  "encoding": "00011------------010-----0101111",
  "variable_fields": ["rd", "rs1", "rs2", "aq", "rl"],
  "extension": ["rv_a"],
  "match": "0x1800202f",
  "mask": "0xf800707f"
}

The extension values match the tags on a catalogue entry, and that is what places the instruction. Merge it in and verify:

npm run sync
npm test && npm run build

The Encoder Validator in the header checks a proposed encoding against every instruction in the database. Give it either a 32-bit pattern of 0, 1 and -, or a match and mask pair in hex; supplying both cross-checks them against each other.

Overlaps are reported as identical, proposed_subset_of_existing, existing_subset_of_proposed, or partial_overlap, each with a plain-language reason and an example 32-bit word that satisfies both patterns.

Pushes to main build and publish to the gh-pages branch automatically. To publish by hand:

npm run deploy

Contributions are welcome, data corrections especially. See CONTRIBUTING.md for setup, the invariants the tests enforce, and the sign-off requirement.

All commits must be signed off under the Developer Certificate of Origin:

git commit -s

Participation is governed by our Code of Conduct. To report a vulnerability, see SECURITY.md.

Apache License 2.0.