diff -r d06ee9c3f780 -r 8eb533b797be .github/workflows/prep_sources.yml
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/.github/workflows/prep_sources.yml	Thu Jul 28 16:54:04 2022 +0200
@@ -0,0 +1,61 @@
+name: Prepare sources
+
+env:
+    beremiz_revisionid: 9fb2ded4f1988440faf546488ee83373825330f4
+    matiec_revisionid: ba00e2b18e7335c03c011e1c6b2a5d99fc3571c3
+    canfestival_revisionid: 12a05e422666c738d1312259703f80150c747cb5
+
+on:
+  workflow_call:
+    outputs:
+      beremiz_revisionid:
+        value: ${{ env.beremiz_revisionid }}
+      matiec_revisionid:
+        value: ${{ env.matiec_revisionid }}
+      canfestival_revisionid:
+        value: ${{ env.canfestival_revisionid }}
+
+jobs:
+  get_sources:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+      with:
+          path: beremiz_public_dist
+
+    # repositories are directly checked out where Makerfile expects them to be
+    - uses: actions/checkout@v3
+      with:
+          repository: beremiz/beremiz
+          ref: ${{ env.beremiz_revisionid }}
+          path: build/sources/beremiz
+
+    - uses: actions/checkout@v3
+      with:
+          repository: beremiz/matiec
+          ref: ${{ env.matiec_revisionid }}
+          path: build/sources/matiec
+
+    - uses: actions/checkout@v3
+      with:
+          repository: beremiz/canfestival
+          ref: ${{ env.canfestival_revisionid }}
+          path: build/sources/canfestival
+
+    - name: Touch expected Makfile targets to shortcut HG checkout
+      run: |
+        touch build/sources/beremiz_${{ env.beremiz_revisionid }}
+        touch build/sources/matiec_${{ env.matiec_revisionid }}
+        touch build/sources/canfestival_${{ env.canfestival_revisionid }}
+        touch build/sources/beremiz_src
+        touch build/sources/matiec_src
+        touch build/sources/canfestival_src
+        touch build/own_sources
+        cat >> build/revisions.txt <<EOF
+        beremiz_public_dist ${{ github.sha }}
+        beremiz ${{ env.beremiz_revisionid }}
+        matiec ${{ env.matiec_revisionid }}
+        canfestival ${{ env.canfestival_revisionid }}
+        EOF
+