[toolchain] Publish architecture-independent utility toolchain

Publish a version of the toolchain container that has not yet had any
architecture-specific packages installed.  This can be used for tasks
such as constructing the multi-architecture ISO and USB disk images
from binaries compiled by the architecture-specific toolchains.

Signed-off-by: Michael Brown <mbrown@fensystems.co.uk>

Author: mcb30

.github/workflows/toolchain.yml

@@ -42,16 +42,17 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        arch:
+        subpkg:
           - arm32
           - arm64
           - i386
           - loong64
           - riscv32
           - riscv64
+          - utils
           - x86_64
     env:
-      pkgname: ipxe-builder-${{ matrix.arch }}
+      pkgname: ipxe-builder-${{ matrix.subpkg }}
       reponame: ghcr.io/${{ github.repository_owner }}
     steps:
 
@@ -68,11 +69,11 @@ jobs:
       - name: Set up builder
         uses: docker/setup-buildx-action@v3
 
-      - name: Build (${{ matrix.arch }})
+      - name: Build (${{ matrix.subpkg }})
         uses: docker/build-push-action@v6
         with:
           context: toolchain
-          target: ${{ matrix.arch }}
+          target: ${{ matrix.subpkg }}
           push: true
           cache-from: |
             type=gha,mode=max,scope=${{ github.ref_name }}-common
@@ -83,15 +84,15 @@ jobs:
         uses: docker/build-push-action@v6
         with:
           context: toolchain
-          target: check-${{ matrix.arch }}
+          target: check-${{ matrix.subpkg }}
           push: false
           load: true
           tags: |
-            check-${{ matrix.arch }}
+            check-${{ matrix.subpkg }}
 
       - name: Test
         run: |
-          docker run --rm check-${{ matrix.arch }}
+          docker run --rm check-${{ matrix.subpkg }}
 
   publish:
     name: Publish
@@ -103,16 +104,17 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        arch:
+        subpkg:
           - arm32
           - arm64
           - i386
           - loong64
           - riscv32
           - riscv64
+          - utils
           - x86_64
     env:
-      pkgname: ipxe-builder-${{ matrix.arch }}
+      pkgname: ipxe-builder-${{ matrix.subpkg }}
       reponame: ghcr.io/${{ github.repository_owner }}
       label: ${{ github.ref_name == 'master' && 'latest' || github.ref_name }}
     steps:

toolchain/Dockerfile

@@ -21,6 +21,29 @@ RUN echo "install_weak_deps=False" >> /etc/dnf/dnf.conf \
 	xz-devel \
     && dnf clean all -y
 
+#
+# Architecture-independent utilities
+#
+
+FROM baseline AS utils
+
+FROM utils AS check-utils
+
+RUN dnf install -y \
+	libcdio \
+	shim-x64 \
+    && dnf clean all -y
+
+ADD https://github.com/ipxe/ipxe.git /ipxe
+
+WORKDIR /ipxe/src
+
+RUN ln -s /bin/true dummy.lkrn
+
+RUN ln -s /boot/efi/EFI/BOOT/BOOTX64.EFI dummy.efi
+
+CMD ./util/genfsimg -o dummy.iso dummy.lkrn dummy.efi && iso-info dummy.iso
+
 #
 # x86_64 toolchain
 #