ci: prepare rootfs after building artifacts

Currently, each test job is rebuilding the artifacts.
We can do this just once after we built the kernel and prepare the
rootfs.
The tests than get ran by invoking the vm with "run_tests={test},{test2}" appended
to boot command.

Signed-off-by: Manu Bretelle <chantr4@gmail.com>

Author: chantra

.github/workflows/test.yml

@@ -156,6 +156,15 @@ jobs:
           toolchain: ${{ matrix.toolchain }}
           kbuild-output: ${{ env.KBUILD_OUTPUT }}
           max-make-jobs: 32
+      - name: Prepare rootfs
+        uses: libbpf/ci/prepare-rootfs@master
+        with:
+          project-name: 'libbpf'
+          arch: ${{ matrix.arch }}
+          kernel: ${{ matrix.kernel }}
+          kernel-root: '.'
+          kbuild-output: ${{ env.KBUILD_OUTPUT }}
+          image-output: 'root.img'
       - name: Tar artifacts
         run: |
           file_list=""
@@ -170,14 +179,9 @@ jobs:
           fi
           # zstd is installed by default in the runner images.
           tar -cf - \
-            "${KBUILD_OUTPUT}"/.config \
-            "${KBUILD_OUTPUT}"/$(KBUILD_OUTPUT="${KBUILD_OUTPUT}" make -s image_name) \
-            "${KBUILD_OUTPUT}"/include/config/auto.conf \
-            "${KBUILD_OUTPUT}"/include/generated/autoconf.h \
-            "${KBUILD_OUTPUT}"/vmlinux \
             ${file_list} \
-            --exclude '*.h' \
-            selftests/bpf/ | zstd -T0 -19 -o vmlinux-${{ matrix.arch }}-${{ matrix.toolchain }}.tar.zst
+            root.img \
+            vmlinuz | zstd -T0 -19 -o vmlinux-${{ matrix.arch }}-${{ matrix.toolchain }}.tar.zst
       - uses: actions/upload-artifact@v3
         with:
           name: vmlinux-${{ matrix.arch }}-${{ matrix.toolchain }}
@@ -205,23 +209,14 @@ jobs:
       - name: Untar artifacts
         # zstd is installed by default in the runner images.
         run: zstd -d -T0  vmlinux-${{ matrix.arch }}-${{ matrix.toolchain }}.tar.zst --stdout | tar -xf -
-      - name: Prepare rootfs
-        uses: libbpf/ci/prepare-rootfs@master
-        with:
-          project-name: 'libbpf'
-          arch: ${{ matrix.arch }}
-          kernel: ${{ matrix.kernel }}
-          kernel-root: '.'
-          kbuild-output: ${{ env.KBUILD_OUTPUT }}
-          image-output: '/tmp/root.img'
-          test: ${{ matrix.test }}
       - name: Run selftests
         uses: libbpf/ci/run-qemu@master
         continue-on-error: ${{ matrix.continue_on_error }}
         timeout-minutes: ${{ matrix.timeout_minutes }}
         with:
           arch: ${{ matrix.arch}}
-          img: '/tmp/root.img'
+          img: '${{ github.workspace }}/root.img'
           vmlinuz: '${{ github.workspace }}/vmlinuz'
           kernel-root: '.'
           max-cpu: 8
+          kernel-test: ${{ matrix.test }}