Build AArch64 Cygwin using Ubuntu cross-toolchain

Author: Blackhex

.github/workflows/cygwin.yml

@@ -10,6 +10,7 @@ on:
 
 jobs:
   fedora-build:
+    if: false
     runs-on: ubuntu-latest
     container: fedora:latest
     strategy:
@@ -90,7 +91,107 @@ jobs:
         scp -pr build/*/winsup/doc/{cygwin-api,cygwin-ug-net,faq} [email protected]:/sourceware/www/sourceware/htdocs/cygwin/doc/${DEST}/
       if: env.HAS_SSH_KEY == 'true'
 
+  ubuntu-build:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - target: aarch64-pc-cygwin
+            runner: ubuntu-24.04-arm
+
+    runs-on: ${{ matrix.runner }}
+    name: Ubuntu cross ${{ matrix.target }}
+
+    env:
+      GH_TOKEN: ${{ github.token }}
+      HAS_SSH_KEY: ${{ secrets.SSH_KEY != '' }}
+
+    steps:
+      - uses: actions/checkout@v3
+
+      # install build tools
+      - name: Install build tools
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y \
+            autoconf \
+            automake \
+            dblatex \
+            docbook2x \
+            docbook-xsl \
+            gawk \
+            gcc-mingw-w64 \
+            make \
+            openssh-client \
+            patch \
+            perl \
+            python3 \
+            python3-lxml \
+            python3-ply \
+            xmlto
+
+      # download toolchain
+      - name: Download toolchain
+        run: |
+          gh release download \
+            --repo Windows-on-ARM-Experiments/mingw-woarm64-build \
+            --pattern aarch64-pc-cygwin-msvcrt-toolchain.tar.gz
+          mkdir -p toolchain
+          tar -xzf aarch64-pc-cygwin-msvcrt-toolchain.tar.gz -C toolchain
+
+      # build
+      - name: Configure, build and install
+        run: |
+          export PATH="$PATH:${{ github.workspace }}/toolchain/bin"
+          mkdir build install
+          (cd winsup && ./autogen.sh)
+          (cd build && ../configure --target=${{ matrix.target }} --prefix=$(realpath $(pwd)/../install) )
+          make -C build
+          make -C build/*/newlib info man
+          make -C build install
+          make -C build/*/newlib install-info install-man
+
+      - name: Upload build folder
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: build
+          retention-days: 1
+          path: ${{ github.workspace }}
+
+      # deploy documentation
+      - name: Deploy documentation
+        env:
+          SSH_AUTH_SOCK: /tmp/ssh_agent.sock
+        run: |
+          # pushes to main are deployed as preview
+          # pushes to cygwin-n.n.n (but not 'cygwin-n.n.n.dev') tags are deployed as stable
+          # other references are ignored by this step
+          case "${{ github.ref }}" in
+            refs/heads/main)
+              DEST='preview'
+              ;;
+            refs/tags/cygwin-[0-9.]*)
+              DEST='stable'
+              ;;
+            *)
+              exit 0
+              ;;
+          esac
+          # unfuck github fuckery of HOME in a container
+          unset HOME
+          # add the hosts public key to known_hosts
+          mkdir -p ~/.ssh/
+          echo "cygwin.com ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIKoejTnTCbXaIIMYfbX7t4tYUOQ2bTxZC3e/td3BageF" >> ~/.ssh/known_hosts
+          # load the key (restricted to scp only) into ssh-agent
+          ssh-agent -a $SSH_AUTH_SOCK > /dev/null
+          ssh-add - <<< "${{ secrets.SSH_KEY }}"
+          # 'make install' doesn't install faq, so instead just deploy from build directory
+          scp -pr build/*/winsup/doc/{cygwin-api,cygwin-ug-net,faq} [email protected]:/sourceware/www/sourceware/htdocs/cygwin/doc/${DEST}/
+        if: env.HAS_SSH_KEY == 'true'
+
   windows-build:
+    if: false
     runs-on: windows-latest
     strategy:
       fail-fast: false