compile riscv in docker

.github/workflows/build.yml

@@ -0,0 +1,25 @@
+name: CI
+on: push
+jobs:
+  build:
+    name: Build C code
+    runs-on: ubuntu-latest
+    container:
+      image: plincar/riscv-gnu-toolchain:2023_03_12
+      # volumes:
+      #   - my_docker_volume:/volume_mount
+    steps:
+      - uses: actions/checkout@v4
+      - name: Check for executables
+        run: |
+          # this really should have been added to path at install time when the container was made
+          export PATH=$PATH:/opt/riscv/gnu-toolchain/rv64/bin
+          riscv64-unknown-elf-gcc --version
+      - name: Build
+        run: |
+          cd tests/test_basic
+          # ls -lah
+          # cat Makefile
+          # make test.hex
+          export PATH=$PATH:/opt/riscv/gnu-toolchain/rv64/bin
+          riscv64-unknown-elf-as -march=rv32i -mabi=ilp32 test.S -o test.o