diff --git a/make_helpers/arch_features.mk b/make_helpers/arch_features.mk
index 5d538cc..8407b57 100644
--- a/make_helpers/arch_features.mk
+++ b/make_helpers/arch_features.mk
@@ -20,27 +20,44 @@
 
 # Enable the features which are mandatory from ARCH version 8.1 and upwards.
 ifeq "8.1" "$(word 1, $(sort 8.1 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
-ENABLE_FEAT_PAN				?=	1
-ENABLE_FEAT_VHE				?=	1
+armv8-1-a-feats         := ENABLE_FEAT_PAN ENABLE_FEAT_VHE
+
+FEAT_LIST               := ${armv8-1-a-feats}
 endif
 
 # Enable the features which are mandatory from ARCH version 8.2 and upwards.
 ifeq "8.2" "$(word 1, $(sort 8.2 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
-ENABLE_FEAT_RAS				?=	1
+armv8-2-a-feats         := ENABLE_FEAT_RAS
+# 8.1 Compliant
+armv8-2-a-feats         += ${armv8-1-a-feats}
+
+FEAT_LIST               := ${armv8-2-a-feats}
+endif
+
+# Enable the features which are mandatory from ARCH version 8.3 and upwards.
+ifeq "8.3" "$(word 1, $(sort 8.3 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
+# 8.2 Compliant
+armv8-3-a-feats         += ${armv8-2-a-feats}
+
+FEAT_LIST               := ${armv8-3-a-feats}
 endif
 
 # Enable the features which are mandatory from ARCH version 8.4 and upwards.
 ifeq "8.4" "$(word 1, $(sort 8.4 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
-ENABLE_FEAT_SEL2			?=	1
-ENABLE_TRF_FOR_NS			?=	1
-ENABLE_FEAT_DIT				?=	1
+armv8-4-a-feats         := ENABLE_FEAT_SEL2 ENABLE_TRF_FOR_NS ENABLE_FEAT_DIT
+# 8.3 Compliant
+armv8-4-a-feats         += ${armv8-3-a-feats}
+
+FEAT_LIST               := ${armv8-4-a-feats}
 endif
 
 # Enable the features which are mandatory from ARCH version 8.5 and upwards.
 ifeq "8.5" "$(word 1, $(sort 8.5 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
-ENABLE_FEAT_RNG				?=	1
-ENABLE_FEAT_SB				?=	1
+armv8-5-a-feats         := ENABLE_FEAT_RNG ENABLE_FEAT_SB
+# 8.4 Compliant
+armv8-5-a-feats         += ${armv8-4-a-feats}
 
+FEAT_LIST               := ${armv8-5-a-feats}
 # Enable Memory tagging, Branch Target Identification for aarch64 only.
 ifeq ($(ARCH), aarch64)
 	mem_tag_arch_support		?= 	yes
@@ -50,20 +67,67 @@
 
 # Enable the features which are mandatory from ARCH version 8.6 and upwards.
 ifeq "8.6" "$(word 1, $(sort 8.6 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
-ENABLE_FEAT_ECV				?=	1
-ENABLE_FEAT_FGT				?=	1
+armv8-6-a-feats         := ENABLE_FEAT_ECV ENABLE_FEAT_FGT
+# 8.5 Compliant
+armv8-6-a-feats         += ${armv8-5-a-feats}
+FEAT_LIST               := ${armv8-6-a-feats}
 endif
 
 # Enable the features which are mandatory from ARCH version 8.7 and upwards.
 ifeq "8.7" "$(word 1, $(sort 8.7 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
-ENABLE_FEAT_HCX				?=	1
+armv8-7-a-feats         := ENABLE_FEAT_HCX
+# 8.6 Compliant
+armv8-7-a-feats         += ${armv8-6-a-feats}
+FEAT_LIST               := ${armv8-7-a-feats}
+endif
+
+# Enable the features which are mandatory from ARCH version 8.8 and upwards.
+ifeq "8.8" "$(word 1, $(sort 8.8 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
+# 8.7 Compliant
+armv8-7-a-feats         += ${armv8-7-a-feats}
+FEAT_LIST               := ${armv8-8-a-feats}
 endif
 
 # Enable the features which are mandatory from ARCH version 8.9 and upwards.
 ifeq "8.9" "$(word 1, $(sort 8.9 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
-ENABLE_FEAT_TCR2			?=	1
+armv8-9-a-feats         := ENABLE_FEAT_TCR2
+# 8.8 Compliant
+armv8-9-a-feats         += ${armv8-8-a-feats}
+FEAT_LIST               := ${armv8-9-a-feats}
 endif
 
+# Enable the features which are mandatory from ARCH version 9.0 and upwards.
+ifeq "9.0" "$(word 1, $(sort 9.0 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
+# 8.5 Compliant
+armv9-0-a-feats         += ${armv8-5-a-feats}
+FEAT_LIST               := ${armv9-0-a-feats}
+endif
+
+# Enable the features which are mandatory from ARCH version 9.1 and upwards.
+ifeq "9.1" "$(word 1, $(sort 9.1 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
+# 8.6 and 9.0 Compliant
+armv9-1-a-feats         += ${armv8-6-a-feats} ${armv9-0-a-feats}
+FEAT_LIST               := ${armv9-1-a-feats}
+endif
+
+# Enable the features which are mandatory from ARCH version 9.2 and upwards.
+ifeq "9.2" "$(word 1, $(sort 9.2 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
+# 8.7 and 9.1 Compliant
+armv9-2-a-feats         += ${armv8-7-a-feats} ${armv9-1-a-feats}
+FEAT_LIST               := ${armv9-2-a-feats}
+endif
+
+# Enable the features which are mandatory from ARCH version 9.3 and upwards.
+ifeq "9.3" "$(word 1, $(sort 9.3 $(ARM_ARCH_MAJOR).$(ARM_ARCH_MINOR)))"
+# 8.8 and 9.2 Compliant
+armv9-3-a-feats         += ${armv8-8-a-feats} ${armv9-2-a-feats}
+FEAT_LIST               := ${armv9-3-a-feats}
+endif
+
+# Set all FEAT_* in FEAT_LIST to '1' if they are not yet defined or set
+# from build commandline options or platform makefile.
+$(eval $(call default_ones, ${sort ${FEAT_LIST}}))
+
 #
 ################################################################################
 # Set mandatory features by default to zero.
diff --git a/make_helpers/build_macros.mk b/make_helpers/build_macros.mk
index 2d2f141..6edc2d6 100644
--- a/make_helpers/build_macros.mk
+++ b/make_helpers/build_macros.mk
@@ -50,6 +50,18 @@
 	$(foreach var,$1,$(eval $(call default_zero,$(var))))
 endef
 
+# Convenience function for setting a variable to 1 if not previously set
+# $(eval $(call default_one,FOO))
+define default_one
+	$(eval $(1) ?= 1)
+endef
+
+# Convenience function for setting a list of variables to 1 if not previously set
+# $(eval $(call default_ones,FOO BAR))
+define default_ones
+	$(foreach var,$1,$(eval $(call default_one,$(var))))
+endef
+
 # Convenience function for adding build definitions
 # $(eval $(call add_define,FOO)) will have:
 # -DFOO if $(FOO) is empty; -DFOO=$(FOO) otherwise