feat(ci): Vivado in GitHub Actions Docker — Closes #604

.github/workflows/build-vivado-image.yml

@@ -0,0 +1,88 @@
+name: Build Vivado Docker Image
+
+# Manually triggered. Builds a ~35 GB Vivado 2025.2 ML Standard image (Artix-7 only)
+# and pushes to ghcr.io/<owner>/t27-vivado:2025.2.
+#
+# Prerequisite (one-time): upload Vivado_2025.2_Lin64.bin (347 MB) as a GitHub Release
+# asset on a tag like `vivado-installer-2025.2`. Or use a self-hosted runner with the
+# installer pre-staged. We default to fetching from the release asset.
+
+on:
+  workflow_dispatch:
+    inputs:
+      installer_release_tag:
+        description: 'GitHub Release tag holding Vivado_2025.2_Lin64.bin (private asset)'
+        required: false
+        default: 'vivado-installer-2025.2'
+      image_tag:
+        description: 'Image tag to push (e.g. 2025.2, 2025.2-artix7)'
+        required: false
+        default: '2025.2'
+
+permissions:
+  contents: read
+  packages: write
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    timeout-minutes: 240  # full Vivado install can take 60-90 min
+    steps:
+      - name: Maximize build space
+        uses: easimon/maximize-build-space@v10
+        with:
+          root-reserve-mb: 4096
+          swap-size-mb: 1024
+          remove-dotnet: 'true'
+          remove-android: 'true'
+          remove-haskell: 'true'
+          remove-codeql: 'true'
+          remove-docker-images: 'true'
+
+      - uses: actions/checkout@v4
+
+      - name: Download Vivado installer from release asset
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TAG: ${{ github.event.inputs.installer_release_tag }}
+        run: |
+          gh release download "$TAG" \
+            --repo "$GITHUB_REPOSITORY" \
+            --pattern "Vivado_2025.2_Lin64.bin" \
+            --dir infra/vivado-docker/
+          ls -lah infra/vivado-docker/Vivado_2025.2_Lin64.bin
+
+      - name: Log in to GHCR
+        uses: docker/login-action@v3
+        with:
+          registry: ghcr.io
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+        with:
+          driver-opts: image=moby/buildkit:latest
+
+      - name: Compute lowercase image name
+        id: img
+        run: |
+          OWNER_LC="$(echo '${{ github.repository_owner }}' | tr '[:upper:]' '[:lower:]')"
+          echo "name=ghcr.io/${OWNER_LC}/t27-vivado" >> "$GITHUB_OUTPUT"
+
+      - name: Build and push image
+        uses: docker/build-push-action@v6
+        with:
+          context: infra/vivado-docker
+          file: infra/vivado-docker/Dockerfile
+          push: true
+          tags: |
+            ${{ steps.img.outputs.name }}:${{ github.event.inputs.image_tag }}
+            ${{ steps.img.outputs.name }}:latest
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
+
+      - name: Print summary
+        run: |
+          echo "Pushed ${{ steps.img.outputs.name }}:${{ github.event.inputs.image_tag }}"
+          echo "Used by .github/workflows/vivado-synth.yml via container: directive."

.github/workflows/vivado-synth.yml

@@ -0,0 +1,142 @@
+name: Vivado Synth (Docker, GH-hosted)
+
+# Runs Vivado synth/P&R/bitstream inside a pre-built Docker image on GitHub-hosted runners.
+# No self-hosted runner, no Railway. Image is built by build-vivado-image.yml.
+#
+# Triggers:
+#   - PR touching fpga/, specs/fpga/, bootstrap/ or this workflow
+#   - workflow_dispatch with design selection
+
+on:
+  workflow_dispatch:
+    inputs:
+      design:
+        description: 'Design to build (blinky | gf16 | phi_heartbeat)'
+        required: false
+        default: 'gf16'
+      uart:
+        description: 'Emit UART telemetry harness (true/false)'
+        required: false
+        default: 'true'
+        type: boolean
+  # PR trigger intentionally disabled until ghcr.io/<owner>/t27-vivado:2025.2 exists.
+  # After running build-vivado-image.yml once, re-enable by uncommenting the pull_request block:
+  # pull_request:
+  #   paths:
+  #     - 'fpga/vivado/**'
+  #     - 'specs/fpga/**'
+  #     - 'bootstrap/src/**'
+  #     - '.github/workflows/vivado-synth.yml'
+
+permissions:
+  contents: read
+  packages: read
+
+jobs:
+  resolve-image:
+    runs-on: ubuntu-latest
+    outputs:
+      image: ${{ steps.img.outputs.image }}
+    steps:
+      - id: img
+        run: |
+          OWNER_LC="$(echo '${{ github.repository_owner }}' | tr '[:upper:]' '[:lower:]')"
+          echo "image=ghcr.io/${OWNER_LC}/t27-vivado:2025.2" >> "$GITHUB_OUTPUT"
+
+  synth:
+    needs: resolve-image
+    runs-on: ubuntu-latest
+    timeout-minutes: 90
+    container:
+      image: ${{ needs.resolve-image.outputs.image }}
+      credentials:
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+      options: --user 0
+    steps:
+      - name: Maximize build space (host side)
+        uses: easimon/maximize-build-space@v10
+        with:
+          root-reserve-mb: 8192
+          swap-size-mb: 1024
+          remove-dotnet: 'true'
+          remove-android: 'true'
+          remove-haskell: 'true'
+          remove-codeql: 'true'
+
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+
+      - name: Print runner & Vivado info
+        run: |
+          uname -a
+          which vivado
+          vivado -version | head -3
+          df -h /
+
+      - name: Install Rust toolchain
+        run: |
+          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable
+          echo "${HOME}/.cargo/bin" >> "$GITHUB_PATH"
+
+      - name: Build t27c (release)
+        run: |
+          cd bootstrap
+          cargo build --release --bin t27c
+          echo "T27C_BIN=$PWD/target/release/t27c" >> "$GITHUB_ENV"
+
+      - name: Generate Verilog from .t27 specs
+        run: |
+          DESIGN="${{ github.event.inputs.design || 'gf16' }}"
+          "$T27C_BIN" fpga-build --smoke \
+            --device xc7a100tcsg324-1 \
+            --top "${DESIGN}_top" \
+            --output build/fpga
+          ls -la build/fpga/generated/ || true
+
+      - name: Run Vivado synth+P&R+bitstream
+        env:
+          DESIGN: ${{ github.event.inputs.design || 'gf16' }}
+          UART_FLAG: ${{ github.event.inputs.uart || 'true' }}
+        run: |
+          cd fpga/vivado
+          vivado -mode batch -nojournal -nolog \
+            -source "build_${DESIGN}.tcl" \
+            -tclargs --uart "$UART_FLAG" --device xc7a100tcsg324-1 \
+            2>&1 | tee vivado.log
+
+      - name: Extract utilization & timing summary (inline awk)
+        run: |
+          cd fpga/vivado
+          awk '
+            /Slice LUTs/         {print}
+            /Slice Registers/    {print}
+            /Block RAM Tile/     {print}
+            /DSPs/               {print}
+            /WNS\(ns\)/          {getline; print "WNS line:", $0}
+          ' vivado.log > utilization_summary.txt || true
+          echo "==== utilization_summary.txt ===="
+          cat utilization_summary.txt
+
+      - name: Upload bitstream
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: vivado-bitstream-${{ github.event.inputs.design || 'gf16' }}
+          path: |
+            fpga/vivado/*.bit
+            fpga/vivado/*.ltx
+          retention-days: 30
+          if-no-files-found: warn
+
+      - name: Upload Vivado logs & utilization
+        uses: actions/upload-artifact@v4
+        if: always()
+        with:
+          name: vivado-log-${{ github.event.inputs.design || 'gf16' }}
+          path: |
+            fpga/vivado/vivado.log
+            fpga/vivado/utilization_summary.txt
+          retention-days: 30
+          if-no-files-found: warn

docs/NOW.md

@@ -1,7 +1,7 @@
 # Current Work — Trinity t27
 
 **Last updated:** 2026-05-14
-**Note:** GF16 4×4 matmul validated on FPGA @ 323 MHz, 40350 LUTs, 64 DSP48E1, 0 latches. **TinyTapeout TTSKY26a submitted** — `gHashTag/tt-trinity-gf16`, CI running. 41.2 GOPS @ 323 MHz | 12.8 GOPS @ 100 MHz.
+**Note:** GF16 4×4 matmul validated on FPGA @ 323 MHz, 40350 LUTs, 64 DSP48E1, 0 latches. **TinyTapeout TTSKY26a submitted** — `gHashTag/tt-trinity-gf16`, CI running. 41.2 GOPS @ 323 MHz | 12.8 GOPS @ 100 MHz. **Vivado CI now runs entirely in GitHub Actions** via a pre-built Docker image on ghcr.io — no self-hosted runner, no Railway. See `infra/vivado-docker/README.md` (PR #622).
 
 ---
 

infra/vivado-docker/Dockerfile

@@ -0,0 +1,59 @@
+# Vivado 2025.2 ML Standard image for t27 FPGA CI.
+# Strips down install to Artix-7 family only (~35 GB on disk) to fit
+# GitHub-hosted ubuntu-latest runner after easimon/maximize-build-space.
+#
+# Build context expects: Vivado_2025.2_Lin64.bin and install_config.txt next to this Dockerfile.
+# Built once and pushed to ghcr.io/ghashtag/t27-vivado:2025.2 by
+# .github/workflows/build-vivado-image.yml (manual dispatch).
+
+FROM ubuntu:22.04 AS installer
+
+ENV DEBIAN_FRONTEND=noninteractive TZ=UTC
+
+# Runtime + installer dependencies for Vivado (libtinfo5 / libncurses5 are the classic gotchas).
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        ca-certificates curl wget xz-utils \
+        libc6 libstdc++6 libtinfo5 libncurses5 libx11-6 libxext6 libxrender1 libxtst6 libxi6 \
+        libfontconfig1 libfreetype6 libgtk2.0-0 libcanberra-gtk-module libgomp1 \
+        libusb-1.0-0 libssl-dev libtinfo-dev \
+        locales \
+    && locale-gen en_US.UTF-8 \
+    && rm -rf /var/lib/apt/lists/*
+
+ENV LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8
+
+COPY Vivado_2025.2_Lin64.bin /tmp/installer.bin
+COPY install_config.txt /tmp/install_config.txt
+
+RUN chmod +x /tmp/installer.bin \
+    && /tmp/installer.bin \
+        --agree XilinxEULA,3rdPartyEULA \
+        --batch Install \
+        --config /tmp/install_config.txt \
+    && rm -f /tmp/installer.bin /tmp/install_config.txt \
+    && find /opt/Xilinx -name "*.tar.gz" -delete 2>/dev/null || true \
+    && find /opt/Xilinx -name "*.zip" -delete 2>/dev/null || true \
+    && rm -rf /opt/Xilinx/Vivado/2025.2/data/parts/xilinx/{kintex,virtex,zynq,versal,spartan,ultrascale}* 2>/dev/null || true
+
+# Final stage: copy only the pruned install to keep image lean.
+FROM ubuntu:22.04
+
+ENV DEBIAN_FRONTEND=noninteractive TZ=UTC LANG=en_US.UTF-8 LC_ALL=en_US.UTF-8
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        ca-certificates \
+        libc6 libstdc++6 libtinfo5 libncurses5 libx11-6 libxext6 libxrender1 libxtst6 libxi6 \
+        libfontconfig1 libfreetype6 libgtk2.0-0 libcanberra-gtk-module libgomp1 \
+        libusb-1.0-0 libssl-dev \
+        locales tini \
+    && locale-gen en_US.UTF-8 \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=installer /opt/Xilinx /opt/Xilinx
+
+ENV PATH="/opt/Xilinx/Vivado/2025.2/bin:${PATH}" \
+    XILINXD_LICENSE_FILE=""
+
+WORKDIR /work
+ENTRYPOINT ["/usr/bin/tini", "--"]
+CMD ["bash"]