prjxray-db/virtex7/README.md

openXC7 Virtex-7 device database (prjxray database/virtex7)

Canonical, version-controlled copy of the prjxray virtex7 device database (segbits / tilegrid / part data) used by the openXC7 flow for the VC707 (xc7vx485tffg1761-2).

Upstream prjxray gitignores its database/ tree (it is fuzzer output), so this data has historically lived only on the fuzzing machine. This repo exists to make it a first-class, diffable, releasable artifact — the canonical source of truth and the durable off-machine backup.

What's here

The full database/virtex7 tree, committed raw (no .gitignore hiding the generated .db/.json):

• segbits_*.db — feature → bit mappings (the fuzzed encoding)
• tilegrid.json, tileconn.json, *.json — geometry / connectivity
• part.yaml, *.csv — part metadata

These are text and diff/blame cleanly — every segbit change is reviewable.

Derived artifacts (NOT stored here — regenerated, published as release assets)

These are also derivatives of licensed code, but the build tooling that produces them is kept in a separate repo under its own licence (see Provenance & licensing below) — it is not part of this database.

• nextpnr chipdb xc7vx485t.bin — built from this DB by nextpnr-xilinx bbaexport.py --xray <this repo> + bbasm (the xc7 / Project X-Ray path; no RapidWright). Its .bba binary format is tied to a specific nextpnr-xilinx commit, pinned in the tooling's manifest.json.
• json2dcp wire oracle xc7vx485tffg1761-2.oracle.txt.gz — built from RapidWright (BuildWireOracle); independent of these segbits.

Build recipes (build-chipdb.sh, build-oracle.sh, cut-release.sh) and the release manifest.json live in v7-johnson-demo/device-db-tools/.

A release tag bundles this DB commit + the chipdb + the oracle + SHA256SUMS, so the three can never drift out of sync (the previous failure mode, where the chipdb and DB carried different dates from different repos).

Reconciliation workflow

Fuzzing / hand-patching happens in place in this directory (it is the prjxray build area). Because the DB is now tracked:

# after a fuzz/patch session that improves the DB:
git status        # shows exactly which segbits changed (invisible before)
git diff          # review the encoding deltas
git add -A && git commit -m "..."   # capture the local patches
git tag device-db-YYYY-MM-DD        # cut a release

Then run device-db-tools/recipes/cut-release.sh (in the demo repo) to build the chipdb + oracle from this commit and stamp the manifest.

Pulling a newer upstream release is a git merge against this repo — conflicts between local patches and the release surface explicitly instead of one copy silently clobbering the other.

See FIXES.md for the substantive segbit corrections this DB carries over a stock prjxray fuzz.

Provenance & licensing

This database is fuzzer output: the bit↔feature correlations were derived by Project X-Ray's fuzzers, which drive Vivado to generate and diff bitstreams. It is distributed under the Project X-Ray licence (ISC) — see LICENSE — as a mirror/extension of the upstream prjxray database, and contains no Xilinx source or proprietary files.

This repo deliberately contains only the database (a derivative-of-licensed- tools artifact). Original tooling that consumes or rebuilds it (device-db-tools/, the SVS suite, json2dcp, the demo) lives in separate repos under their own licences, to keep our original code cleanly separated from derivatives of licensed code.