CI: Add testing for AArch64 :^)

This should help us avoid accidentally breaking the build for AArch64.
Currently, some tests are expected to fail, so CI runs will be
considered successful even if the kernel panics or if there are test
failures.

For now, we have to build Qemu with a custom patch from source in order
for SystemServer to detect self-test mode.

.github/workflows/cmake.yml

@@ -22,9 +22,13 @@ jobs:
       matrix:
         debug-options: ['ALL_DEBUG', 'NORMAL_DEBUG']
         os: [ubuntu-22.04]
-        arch: ['x86_64']
+        arch: ['x86_64', 'aarch64']
         # If ccache is broken and you would like to bust the ccache cache on Github Actions, increment this:
         ccache-mark: [0]
+        exclude:
+          # We currently manually disable the ALL_DEBUG build on AArch64 for sake of saving CI time, as it's not our main target.
+          - debug-options: 'ALL_DEBUG'
+            arch: 'aarch64'
 
     steps:
       # Pull requests can trail behind `master` and can cause breakage if merging before running the CI checks on an updated branch.
@@ -56,6 +60,10 @@ jobs:
           sudo add-apt-repository 'deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-15 main'
           sudo apt-get update
           sudo apt-get install -y clang-format-15 ccache e2fsprogs gcc-12 g++-12 libstdc++-12-dev libmpfr-dev libmpc-dev ninja-build optipng qemu-utils qemu-system-i386 unzip
+          if ${{ matrix.arch == 'aarch64' }}; then
+            # FIXME: Remove this when we no longer build our own Qemu binary.
+            sudo apt-get install libgtk-3-dev libpixman-1-dev libsdl2-dev libslirp-dev
+          fi
       - name: Install JS dependencies
         run: sudo npm install -g prettier@2.7.1
       - name: Install Python dependencies
@@ -105,6 +113,26 @@ jobs:
           path: ${{ github.workspace }}/Toolchain/Local/${{ matrix.arch }}
           key: ${{ steps.toolchain-cache.outputs.cache-primary-key }}
 
+      # FIXME: Qemu currently needs a local patch for AArch64 testing. It is included in Qemu 8.1; remove this when upgrading!
+      - name: AArch64 Qemu cache
+        id: qemu-cache
+        uses: actions/cache/restore@v3
+        if: ${{ matrix.arch == 'aarch64' }}
+        with:
+          path: ${{ github.workspace }}/Toolchain/Local/qemu
+          key: ${{ runner.os }}-qemu-${{ hashFiles('Ports/qemu/version.sh', 'Toolchain/BuildQemu.sh', 'Toolchain/Patches/qemu/*.patch') }}
+
+      - name: Build AArch64 Qemu
+        if: ${{ matrix.arch == 'aarch64' && !steps.qemu-cache.outputs.cache-hit }}
+        run: ${{ github.workspace }}/Toolchain/BuildQemu.sh
+
+      - name: Update AArch64 Qemu cache
+        uses: actions/cache/save@v3
+        if: ${{ github.event_name != 'pull_request' && matrix.arch == 'aarch64' && !steps.qemu-cache.outputs.cache-hit }}
+        with:
+          path: ${{ github.workspace }}/Toolchain/Local/qemu
+          key: ${{ steps.qemu-cache.outputs.cache-primary-key }}
+
       - name: ccache(1) cache
         # Pull the ccache *after* building the toolchain, in case building the Toolchain somehow interferes.
         uses: actions/cache/restore@v3
@@ -225,7 +253,12 @@ jobs:
           sudo cat fsmount/home/anon/test-results.log
           if ! sudo grep -q "Failed: 0" fsmount/home/anon/test-results.log
           then
-            echo "::error :^( Tests failed, failing job"
+            if ${{ matrix.arch == 'aarch64' }}; then
+              # FIXME: Remove this once all tests pass on AArch64
+              echo "::warning:: :^( Some tests failed"
+              exit 0
+            fi
+            echo "::error:: :^( Tests failed, failing job"
             exit 1
           fi
           echo "::endgroup::"