CI: Add support for 32-bit arm

qemu emulates the virt machine running a cortex-a7.

kernel-arm-release.config corresponds to:
- arch/arm/configs/realview_defconfig (includes cortex-a7 virt support)
- remove unused kernel infrastructure and drivers
- enable rust support, enable rust samples (as modules)
- enable android/binder rust support
- switch from SLAB to SLUB

kernel-arm-debug.config corresponds to:
- kernel-arm-release.config
- add debug settings under "Kernel Hacking", borrowed from arm64
- use RUST_OPT_LEVEL_2 to prevent stack overflows
- enable CONFIG_KASAN

Signed-off-by: Sven Van Asbroeck <[email protected]>

Author: Sven Van Asbroeck

.github/workflows/ci.yaml

@@ -10,16 +10,19 @@ jobs:
 
     strategy:
       matrix:
-        arch: [arm64, ppc64le, x86_64]
+        arch: [arm, arm64, ppc64le, x86_64]
         toolchain: [gcc, clang, llvm]
         config: [debug, release]
         rustc: [2021-02-20]
         output: [src] # [src, build]
         install: [rustup] # [rustup, standalone]
         sysroot: [common] # [common, custom]
 
-        # Exclude `LLVM=1` where not supported.
         exclude:
+          # arm 32-bit gcc not yet supported
+          - arch: arm
+            toolchain: gcc
+          # Exclude `LLVM=1` where not supported.
           - arch: ppc64le
             toolchain: llvm
 
@@ -81,6 +84,14 @@ jobs:
           echo 'QEMU_ARCH=ppc64' >> $GITHUB_ENV
           echo 'QEMU_MACHINE=pseries' >> $GITHUB_ENV
           echo 'QEMU_CPU=POWER9' >> $GITHUB_ENV
+      - if: matrix.arch == 'arm'
+        run: |
+          echo 'MAKE_ARCH=ARCH=arm' >> $GITHUB_ENV
+          echo 'MAKE_CROSS_COMPILE=CROSS_COMPILE=arm-linux-gnueabi-' >> $GITHUB_ENV
+          echo 'IMAGE_PATH=arch/arm/boot/zImage' >> $GITHUB_ENV
+          echo 'QEMU_ARCH=arm' >> $GITHUB_ENV
+          echo 'QEMU_MACHINE=virt' >> $GITHUB_ENV
+          echo 'QEMU_CPU=cortex-a7' >> $GITHUB_ENV
 
       - if: matrix.toolchain == 'clang'
         run: echo 'MAKE_TOOLCHAIN=CC=clang-11' >> $GITHUB_ENV
@@ -105,6 +116,8 @@ jobs:
       - run: echo $(llvm-config-11 --bindir) >> $GITHUB_PATH
 
       # Setup: GCC
+      - if: matrix.arch == 'arm'
+        run: sudo apt-get install -y gcc-arm-linux-gnueabi lzop
       - if: matrix.arch == 'arm64'
         run: sudo apt-get install -y gcc-aarch64-linux-gnu
       - if: matrix.arch == 'ppc64le'
@@ -116,7 +129,7 @@ jobs:
       # Setup: QEMU
       - if: matrix.arch == 'x86_64'
         run: sudo apt-get install -y qemu-system-x86
-      - if: matrix.arch == 'arm64'
+      - if: matrix.arch == 'arm' || matrix.arch == 'arm64'
         run: sudo apt-get install -y qemu-system-arm
       - if: matrix.arch == 'ppc64le'
         run: sudo apt-get install -y qemu-system-ppc