diff --git a/core/Makefile b/core/Makefile
index b3870e5..94fc88e 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -287,6 +287,11 @@
 endif
 endif
 
+# Do this early because sysprop.mk depends on BUILT_KERNEL_VERSION_FILE_FOR_UFFD_GC.
+ifeq (default,$(ENABLE_UFFD_GC))
+BUILT_KERNEL_VERSION_FILE_FOR_UFFD_GC := $(OUT_DIR)/soong/dexpreopt/kernel_version_for_uffd_gc.txt
+endif # ENABLE_UFFD_GC
+
 include $(BUILD_SYSTEM)/sysprop.mk
 
 # ----------------------------------------------------------------
@@ -5256,6 +5261,34 @@
 
 endif # PRODUCT_OTA_ENFORCE_VINTF_KERNEL_REQUIREMENTS
 
+ifeq (default,$(ENABLE_UFFD_GC))
+
+ifneq (,$(BUILT_KERNEL_VERSION_FILE))
+$(BUILT_KERNEL_VERSION_FILE_FOR_UFFD_GC): $(BUILT_KERNEL_VERSION_FILE)
+$(BUILT_KERNEL_VERSION_FILE_FOR_UFFD_GC):
+	cp $(BUILT_KERNEL_VERSION_FILE) $(BUILT_KERNEL_VERSION_FILE_FOR_UFFD_GC)
+else
+# We make this a warning rather than an error to avoid breaking too many builds. When it happens,
+# we use a placeholder as the kernel version, which is consumed by uffd_gc_utils.py.
+$(BUILT_KERNEL_VERSION_FILE_FOR_UFFD_GC):
+	echo $$'\
+Unable to determine UFFD GC flag because the kernel version is not available and\n\
+PRODUCT_ENABLE_UFFD_GC is "default".\n\
+You can fix this by:\n\
+  1. [Recommended] Making the kernel version available.\n\
+    (1). Set PRODUCT_OTA_ENFORCE_VINTF_KERNEL_REQUIREMENTS to "true".\n\
+    (2). If you are still getting this message after doing so, see the warning about\n\
+         PRODUCT_OTA_ENFORCE_VINTF_KERNEL_REQUIREMENTS in the build logs.\n\
+  or\n\
+  2. Explicitly setting PRODUCT_ENABLE_UFFD_GC to "true" or "false" based on the kernel version.\n\
+    (1). Set PRODUCT_ENABLE_UFFD_GC to "true" if the kernel is a GKI kernel and is android12-5.4\n\
+         or above, or a non-GKI kernel that supports userfaultfd(2) and MREMAP_DONTUNMAP.\n\
+    (2). Set PRODUCT_ENABLE_UFFD_GC to "false" otherwise.'\
+	  && echo '<unknown-kernel>' > $@
+endif # BUILT_KERNEL_VERSION_FILE
+
+endif # ENABLE_UFFD_GC == "default"
+
 # -- Check VINTF compatibility of build.
 # Skip partial builds; only check full builds. Only check if:
 # - PRODUCT_ENFORCE_VINTF_MANIFEST is true
diff --git a/core/art_config.mk b/core/art_config.mk
index f47a8e2..54bfd6b 100644
--- a/core/art_config.mk
+++ b/core/art_config.mk
@@ -12,38 +12,15 @@
 # ENABLE_UFFD_GC: Whether to use userfaultfd GC.
 
 config_enable_uffd_gc := \
-  $(firstword $(OVERRIDE_ENABLE_UFFD_GC) $(PRODUCT_ENABLE_UFFD_GC))
+  $(firstword $(OVERRIDE_ENABLE_UFFD_GC) $(PRODUCT_ENABLE_UFFD_GC) default)
 
-ifeq (,$(filter-out default,$(config_enable_uffd_gc)))
-  ENABLE_UFFD_GC := true
-
-  # Disable userfaultfd GC if the device doesn't support it (i.e., if
-  # `min(ro.board.api_level ?? ro.board.first_api_level ?? MAX_VALUE,
-  #      ro.product.first_api_level ?? ro.build.version.sdk ?? MAX_VALUE) < 31`)
-  # This logic aligns with how `ro.vendor.api_level` is calculated in
-  # `system/core/init/property_service.cpp`.
-  # We omit the check on `ro.build.version.sdk` here because we are on the latest build system.
-  board_api_level := $(firstword $(BOARD_API_LEVEL) $(BOARD_SHIPPING_API_LEVEL))
-  ifneq (,$(board_api_level))
-    ifeq (true,$(call math_lt,$(board_api_level),31))
-      ENABLE_UFFD_GC := false
-    endif
-  endif
-
-  ifneq (,$(PRODUCT_SHIPPING_API_LEVEL))
-    ifeq (true,$(call math_lt,$(PRODUCT_SHIPPING_API_LEVEL),31))
-      ENABLE_UFFD_GC := false
-    endif
-  endif
-else ifeq (true,$(config_enable_uffd_gc))
-  ENABLE_UFFD_GC := true
-else ifeq (false,$(config_enable_uffd_gc))
-  ENABLE_UFFD_GC := false
-else
+ifeq (,$(filter default true false,$(config_enable_uffd_gc)))
   $(error Unknown PRODUCT_ENABLE_UFFD_GC value: $(config_enable_uffd_gc))
 endif
 
-ADDITIONAL_PRODUCT_PROPERTIES += ro.dalvik.vm.enable_uffd_gc=$(ENABLE_UFFD_GC)
+ENABLE_UFFD_GC := $(config_enable_uffd_gc)
+# If the value is "default", it will be mangled by post_process_props.py.
+ADDITIONAL_PRODUCT_PROPERTIES += ro.dalvik.vm.enable_uffd_gc=$(config_enable_uffd_gc)
 
 # Create APEX_BOOT_JARS_EXCLUDED which is a list of jars to be removed from
 # ApexBoorJars when built from mainline prebuilts.
diff --git a/core/dex_preopt.mk b/core/dex_preopt.mk
index 37a389f..08311ca 100644
--- a/core/dex_preopt.mk
+++ b/core/dex_preopt.mk
@@ -57,6 +57,7 @@
 # Build the boot.zip which contains the boot jars and their compilation output
 # We can do this only if preopt is enabled and if the product uses libart config (which sets the
 # default properties for preopting).
+# At the time of writing, this is only for ART Cloud.
 ifeq ($(WITH_DEXPREOPT), true)
 ifneq ($(WITH_DEXPREOPT_ART_BOOT_IMG_ONLY), true)
 ifeq ($(PRODUCT_USES_DEFAULT_ART_CONFIG), true)
@@ -95,15 +96,16 @@
 bootclasspath_locations_arg := $(subst $(space),:,$(DEXPREOPT_BOOTCLASSPATH_DEX_LOCATIONS))
 boot_images := $(subst :,$(space),$(DEXPREOPT_IMAGE_LOCATIONS_ON_DEVICE$(DEXPREOPT_INFIX)))
 boot_image_arg := $(subst $(space),:,$(patsubst /%,%,$(boot_images)))
-dex2oat_extra_args := $(if $(filter true,$(ENABLE_UFFD_GC)),--runtime-arg -Xgc:CMC)
+uffd_gc_flag_txt := $(OUT_DIR)/soong/dexpreopt/uffd_gc_flag.txt
 
 boot_zip_metadata_txt := $(dir $(boot_zip))boot_zip/METADATA.txt
+$(boot_zip_metadata_txt): $(uffd_gc_flag_txt)
 $(boot_zip_metadata_txt):
 	rm -f $@
 	echo "bootclasspath = $(bootclasspath_arg)" >> $@
 	echo "bootclasspath-locations = $(bootclasspath_locations_arg)" >> $@
 	echo "boot-image = $(boot_image_arg)" >> $@
-	echo "extra-args = $(dex2oat_extra_args)" >> $@
+	echo "extra-args = `cat $(uffd_gc_flag_txt)`" >> $@
 
 $(call dist-for-goals, droidcore, $(boot_zip_metadata_txt))
 
diff --git a/core/dex_preopt_config.mk b/core/dex_preopt_config.mk
index 10fbe8f..d51de33 100644
--- a/core/dex_preopt_config.mk
+++ b/core/dex_preopt_config.mk
@@ -122,7 +122,7 @@
   $(call add_json_str,  Dex2oatXmx,                              $(DEX2OAT_XMX))
   $(call add_json_str,  Dex2oatXms,                              $(DEX2OAT_XMS))
   $(call add_json_str,  EmptyDirectory,                          $(OUT_DIR)/empty)
-  $(call add_json_bool, EnableUffdGc,                            $(filter true,$(ENABLE_UFFD_GC)))
+  $(call add_json_str,  EnableUffdGc,                            $(ENABLE_UFFD_GC))
 
 ifdef TARGET_ARCH
   $(call add_json_map,  CpuVariant)
diff --git a/core/sysprop.mk b/core/sysprop.mk
index 4e8e976..652ca97 100644
--- a/core/sysprop.mk
+++ b/core/sysprop.mk
@@ -124,7 +124,7 @@
     $(eval _option := --allow-dup)\
 )
 
-$(2): $(POST_PROCESS_PROPS) $(INTERNAL_BUILD_ID_MAKEFILE) $(3) $(6)
+$(2): $(POST_PROCESS_PROPS) $(INTERNAL_BUILD_ID_MAKEFILE) $(3) $(6) $(BUILT_KERNEL_VERSION_FILE_FOR_UFFD_GC)
 	$(hide) echo Building $$@
 	$(hide) mkdir -p $$(dir $$@)
 	$(hide) rm -f $$@ && touch $$@
@@ -148,7 +148,10 @@
 	        echo "$$(line)" >> $$@;\
 	    )\
 	)
-	$(hide) $(POST_PROCESS_PROPS) $$(_option) --sdk-version $(PLATFORM_SDK_VERSION) $$@ $(5)
+	$(hide) $(POST_PROCESS_PROPS) $$(_option) \
+	  --sdk-version $(PLATFORM_SDK_VERSION) \
+	  --kernel-version-file-for-uffd-gc "$(BUILT_KERNEL_VERSION_FILE_FOR_UFFD_GC)" \
+	  $$@ $(5)
 	$(hide) $(foreach file,$(strip $(6)),\
 	    if [ -f "$(file)" ]; then\
 	        cat $(file) >> $$@;\