py/mkrules.mk: Use partial clone for submodules if available.

pi-anl · pi-anl · commit 457663fc5157 · 2024-11-06T10:33:19.000+11:00
Signed-off-by: Andrew Leech &lt;andrew.leech@planetinnovation.com.au&gt;
diff --git a/py/mkrules.mk b/py/mkrules.mk
@@ -252,7 +252,11 @@ submodules:
 	$(ECHO) "Updating submodules: $(GIT_SUBMODULES)"
 ifneq ($(GIT_SUBMODULES),)
 	$(Q)cd $(TOP) && git submodule sync $(GIT_SUBMODULES)
-	$(Q)cd $(TOP) && git submodule update --init $(GIT_SUBMODULES)
+	# If available, do blobless partial clones of submodules to save time and space.
+	# A blobless partial clone lazily fetches data as needed, but has all the metadata available (tags, etc.).
+	# Fallback to standard submodule update if blobless isn't available (earlier than 2.36.0)
+	$(Q)cd $(TOP) && git submodule update --init $(GIT_SUBMODULES) --filter=blob:none || \
+	  git submodule update --init $(GIT_SUBMODULES)	               
 endif
 .PHONY: submodules
 
