diff --git a/packages.yaml b/packages.yaml
index e841028bd47ec8faa7d32cf957513a8816fc49b7..c16e3313f79589b7f8ec0cc67d937d55491ea2fe 100644
--- a/packages.yaml
+++ b/packages.yaml
@@ -1,16 +1,24 @@
 packages:
     all:
+        # collab-specific settings
         target: [x86_64]
         compiler: [gcc@10.3.0]
     python:
+        # collab-specific settings
         version: [3.8.11]
     r:
         version: [4.1.3]
+        # EM: +X fixes build for collab
         variants: [+X]
     py-torch:
+        # ECM: keep at latest w.r.t. tracked upstream spack
         version: [1.11.0]
+        # ECM: No cuda nor rocm in collab VMs.
+        #      I did not try to minimize the specification any further.
         variants: [~cuda~rocm~valgrind~mkldnn~mpi~gloo+tensorpipe~onnx_ml]
     py-jax:
+        # ECM: No cuda in collab VMs.
         variants: [~cuda]
     py-jaxlib:
+        # ECM: No cuda in collab VMs.
         variants: [~cuda]