make_helpers/arch_features.mk - filogic/atf - Gitiles

 #
 # Copyright (c) 2022-2024, Arm Limited. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #

 # This file lists all of the architectural features, and initializes
 # and enables them based on the configured architecture version.

 # This file follows the following format:
 #   - Enable mandatory feature if applicable to an Arch Version.
 #   - By default disable any mandatory features if they have not been defined yet.
 #   - Disable or enable any optional feature this would be enabled/disabled if needed by platform.

 #
 ################################################################################
 # Enable Mandatory features based on Arch versions.
 ################################################################################
 #

 # 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
 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
 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
 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

 # Enable Memory tagging, Branch Target Identification for aarch64 only.
 ifeq ($(ARCH), aarch64)
 	mem_tag_arch_support		:= 	yes
 endif #(ARCH=aarch64)

 endif

 # 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
 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
 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
 endif

 #
 ################################################################################
 # Set mandatory features by default to zero.
 ################################################################################
 #

 #----
 # 8.1
 #----

 # Flag to enable access to Privileged Access Never bit of PSTATE.
 ENABLE_FEAT_PAN			?=	0

 # Flag to enable Virtualization Host Extensions.
 ENABLE_FEAT_VHE			?=	0

 #----
 # 8.2
 #----

 # Enable RAS Support.
 ENABLE_FEAT_RAS			?=	0

 #----
 # 8.3
 #----

 # Flag to enable Pointer Authentication. Internal flag not meant for
 # direct setting. Use BRANCH_PROTECTION to enable PAUTH.
 ENABLE_PAUTH			?=	0

 # Include pointer authentication (ARMv8.3-PAuth) registers in cpu context. This
 # must be set to 1 if the platform wants to use this feature in the Secure
 # world. It is not necessary for use in the Non-secure world.
 CTX_INCLUDE_PAUTH_REGS		?=	0


 #----
 # 8.4
 #----

 # Flag to enable Secure EL-2 feature.
 ENABLE_FEAT_SEL2		?=	0

 # By default, disable trace filter control register access to lower non-secure
 # exception levels, i.e. NS-EL2, or NS-EL1 if NS-EL2 is implemented, but
 # trace filter control register access is unused if FEAT_TRF is implemented.
 ENABLE_TRF_FOR_NS		?=	0

 # Flag to enable Data Independent Timing instructions.
 ENABLE_FEAT_DIT			?=	0

 #----
 # 8.5
 #----

 # Flag to enable Branch Target Identification.
 # Internal flag not meant for direct setting.
 # Use BRANCH_PROTECTION to enable BTI.
 ENABLE_BTI			?=	0

 # Flag to enable access to the Random Number Generator registers.
 ENABLE_FEAT_RNG			?=	0

 # Flag to enable Speculation Barrier Instruction.
 ENABLE_FEAT_SB			?=	0

 #----
 # 8.6
 #----

 # Flag to enable access to the CNTPOFF_EL2 register.
 ENABLE_FEAT_ECV			?=	0

 # Flag to enable access to the HDFGRTR_EL2 register.
 ENABLE_FEAT_FGT			?=	0

 #----
 # 8.7
 #----

 # Flag to enable access to the HCRX_EL2 register by setting SCR_EL3.HXEn.
 ENABLE_FEAT_HCX			?=	0

 #----
 # 8.9
 #----

 # Flag to enable access to TCR2 (FEAT_TCR2).
 ENABLE_FEAT_TCR2		?=	0

 #
 ################################################################################
 # Optional Features defaulted to 0 or 2, if they are not enabled from
 # build option. Can also be disabled or enabled by platform if needed.
 ################################################################################
 #

 #----
 # 8.0
 #----

 # Flag to enable CSV2_2 extension.
 ENABLE_FEAT_CSV2_2			?=	0

 # Flag to enable CSV2_3 extension. FEAT_CSV2_3 enables access to the
 # SCXTNUM_ELx register.
 ENABLE_FEAT_CSV2_3			?=	0

 # By default, disable access of trace system registers from NS lower
 # ELs  i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused if
 # system register trace is implemented. This feature is available if
 # trace unit such as ETMv4.x, This feature is OPTIONAL and is only
 # permitted in Armv8 implementations.
 ENABLE_SYS_REG_TRACE_FOR_NS		?=	0

 #----
 # 8.2
 #----

 # Build option to enable/disable the Statistical Profiling Extension,
 # keep it enabled by default for AArch64.
 ifeq (${ARCH},aarch64)
        ENABLE_SPE_FOR_NS		?=	2
 else ifeq (${ARCH},aarch32)
        ifneq ($(or $(ENABLE_SPE_FOR_NS),0),0)
               $(error ENABLE_SPE_FOR_NS is not supported for AArch32)
        else
               ENABLE_SPE_FOR_NS		:=	0
        endif
 endif

 # Enable SVE for non-secure world by default.
 ifeq (${ARCH},aarch64)
        ENABLE_SVE_FOR_NS		?=	2
 # SVE is only supported on AArch64 so disable it on AArch32.
 else ifeq (${ARCH},aarch32)
        ifneq ($(or $(ENABLE_SVE_FOR_NS),0),0)
               $(error ENABLE_SVE_FOR_NS is not supported for AArch32)
        else
               ENABLE_SVE_FOR_NS 	:=	0
        endif
 endif

 #----
 # 8.4
 #----

 # Feature flags for supporting Activity monitor extensions.
 ENABLE_FEAT_AMU				?=	0
 ENABLE_AMU_AUXILIARY_COUNTERS		?=	0
 ENABLE_AMU_FCONF			?=	0
 AMU_RESTRICT_COUNTERS			?=	0

 # Build option to enable MPAM for lower ELs.
 # Enabling it by default
 ifeq (${ARCH},aarch64)
         ENABLE_FEAT_MPAM		?=	2
 else ifeq (${ARCH},aarch32)
         ifneq ($(or $(ENABLE_FEAT_MPAM),0),0)
                 $(error ENABLE_FEAT_MPAM is not supported for AArch32)
         else
                 ENABLE_FEAT_MPAM	:=	0
         endif
 endif

 # Include nested virtualization control (Armv8.4-NV) registers in cpu context.
 # This must be set to 1 if architecture implements Nested Virtualization
 # Extension and platform wants to use this feature in the Secure world.
 CTX_INCLUDE_NEVE_REGS			?=	0

 #----
 # 8.5
 #----

 # Flag to enable support for EL3 trapping of reads of the RNDR and RNDRRS
 # registers, by setting SCR_EL3.TRNDR.
 ENABLE_FEAT_RNG_TRAP			?=	0

 # Enable Memory Tagging Extension. This must be set to 1 if the platform wants
 # to use this feature in the Secure world and MTE is enabled at ELX.
 ifeq ($(CTX_INCLUDE_MTE_REGS),1)
         $(warning CTX_INCLUDE_MTE_REGS option is deprecated use ENABLE_FEAT_MTE, Enabling ENABLE_FEAT_MTE)
         ENABLE_FEAT_MTE                 ?=      1
 endif
 ifeq (${ARCH},aarch32)
         ifneq ($(or $(ENABLE_FEAT_MTE),0),0)
                 $(error ENABLE_FEAT_MTE is not supported for AArch32)
         endif
 endif
 ENABLE_FEAT_MTE		                ?=	0

 #----
 # 8.6
 #----

 # Flag to enable AMUv1p1 extension.
 ENABLE_FEAT_AMUv1p1			?=	0

 # Flag to enable delayed trapping of WFE instruction (FEAT_TWED).
 ENABLE_FEAT_TWED			?=	0

 # In v8.6+ platforms with delayed trapping of WFE being supported
 # via FEAT_TWED, this flag takes the delay value to be set in the
 # SCR_EL3.TWEDEL(4bit) field, when FEAT_TWED is implemented.
 # By default it takes 0, and need to be updated by the platforms.
 TWED_DELAY				?=	0

 # Disable MTPMU if FEAT_MTPMU is supported.
 DISABLE_MTPMU				?=	0

 #----
 # 8.9
 #----

 # Flag to enable NoTagAccess memory region attribute for stage 2 of translation.
 ENABLE_FEAT_MTE_PERM			?=	0

 # Flag to enable access to Stage 2 Permission Indirection (FEAT_S2PIE).
 ENABLE_FEAT_S2PIE			?=	0

 # Flag to enable access to Stage 1 Permission Indirection (FEAT_S1PIE).
 ENABLE_FEAT_S1PIE			?=	0

 # Flag to enable access to Stage 2 Permission Overlay (FEAT_S2POE).
 ENABLE_FEAT_S2POE			?=	0

 # Flag to enable access to Stage 1 Permission Overlay (FEAT_S1POE).
 ENABLE_FEAT_S1POE			?=	0

 #----
 # 9.0
 #----

 # Flag to enable Realm Management Extension (FEAT_RME).
 ENABLE_RME				?=	0

 # Scalable Matrix Extension for non-secure world.
 ENABLE_SME_FOR_NS			?=	0

 # Scalable Vector Extension for secure world.
 ENABLE_SVE_FOR_SWD			?=	0

 # By default, disable access of trace buffer control registers from NS
 # lower ELs  i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused
 # if FEAT_TRBE is implemented.
 # Note FEAT_TRBE is only supported on AArch64 - therefore do not enable in
 # AArch32.
 ifeq (${ARCH},aarch64)
         ENABLE_TRBE_FOR_NS		?=	0
 else ifeq (${ARCH},aarch32)
         ifneq ($(or $(ENABLE_TRBE_FOR_NS),0),0)
                $(error ENABLE_TRBE_FOR_NS is not supported for AArch32)
         else
                ENABLE_TRBE_FOR_NS 	:=	0
         endif
 endif

 #----
 # 9.2
 #----

 # Scalable Matrix Extension version 2 for non-secure world.
 ENABLE_SME2_FOR_NS			?=	0

 # Scalable Matrix Extension for secure world.
 ENABLE_SME_FOR_SWD			?=	0

 # By default, disable access to branch record buffer control registers from NS
 # lower ELs i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused
 # if FEAT_BRBE is implemented.
 ENABLE_BRBE_FOR_NS			?=	0

 #----
 #9.4
 #----

 # Flag to enable access to Guarded Control Stack (FEAT_GCS).
 ENABLE_FEAT_GCS				?=	0
	#
	# Copyright (c) 2022-2024, Arm Limited. All rights reserved.
	#
	# SPDX-License-Identifier: BSD-3-Clause
	#

	# This file lists all of the architectural features, and initializes
	# and enables them based on the configured architecture version.

	# This file follows the following format:
	# - Enable mandatory feature if applicable to an Arch Version.
	# - By default disable any mandatory features if they have not been defined yet.
	# - Disable or enable any optional feature this would be enabled/disabled if needed by platform.

	#
	################################################################################
	# Enable Mandatory features based on Arch versions.
	################################################################################
	#

	# 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
	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
	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
	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

	# Enable Memory tagging, Branch Target Identification for aarch64 only.
	ifeq ($(ARCH), aarch64)
	mem_tag_arch_support := yes
	endif #(ARCH=aarch64)

	endif

	# 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
	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
	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
	endif

	#
	################################################################################
	# Set mandatory features by default to zero.
	################################################################################
	#

	#----
	# 8.1
	#----

	# Flag to enable access to Privileged Access Never bit of PSTATE.
	ENABLE_FEAT_PAN ?= 0

	# Flag to enable Virtualization Host Extensions.
	ENABLE_FEAT_VHE ?= 0

	#----
	# 8.2
	#----

	# Enable RAS Support.
	ENABLE_FEAT_RAS ?= 0

	#----
	# 8.3
	#----

	# Flag to enable Pointer Authentication. Internal flag not meant for
	# direct setting. Use BRANCH_PROTECTION to enable PAUTH.
	ENABLE_PAUTH ?= 0

	# Include pointer authentication (ARMv8.3-PAuth) registers in cpu context. This
	# must be set to 1 if the platform wants to use this feature in the Secure
	# world. It is not necessary for use in the Non-secure world.
	CTX_INCLUDE_PAUTH_REGS ?= 0


	#----
	# 8.4
	#----

	# Flag to enable Secure EL-2 feature.
	ENABLE_FEAT_SEL2 ?= 0

	# By default, disable trace filter control register access to lower non-secure
	# exception levels, i.e. NS-EL2, or NS-EL1 if NS-EL2 is implemented, but
	# trace filter control register access is unused if FEAT_TRF is implemented.
	ENABLE_TRF_FOR_NS ?= 0

	# Flag to enable Data Independent Timing instructions.
	ENABLE_FEAT_DIT ?= 0

	#----
	# 8.5
	#----

	# Flag to enable Branch Target Identification.
	# Internal flag not meant for direct setting.
	# Use BRANCH_PROTECTION to enable BTI.
	ENABLE_BTI ?= 0

	# Flag to enable access to the Random Number Generator registers.
	ENABLE_FEAT_RNG ?= 0

	# Flag to enable Speculation Barrier Instruction.
	ENABLE_FEAT_SB ?= 0

	#----
	# 8.6
	#----

	# Flag to enable access to the CNTPOFF_EL2 register.
	ENABLE_FEAT_ECV ?= 0

	# Flag to enable access to the HDFGRTR_EL2 register.
	ENABLE_FEAT_FGT ?= 0

	#----
	# 8.7
	#----

	# Flag to enable access to the HCRX_EL2 register by setting SCR_EL3.HXEn.
	ENABLE_FEAT_HCX ?= 0

	#----
	# 8.9
	#----

	# Flag to enable access to TCR2 (FEAT_TCR2).
	ENABLE_FEAT_TCR2 ?= 0

	#
	################################################################################
	# Optional Features defaulted to 0 or 2, if they are not enabled from
	# build option. Can also be disabled or enabled by platform if needed.
	################################################################################
	#

	#----
	# 8.0
	#----

	# Flag to enable CSV2_2 extension.
	ENABLE_FEAT_CSV2_2 ?= 0

	# Flag to enable CSV2_3 extension. FEAT_CSV2_3 enables access to the
	# SCXTNUM_ELx register.
	ENABLE_FEAT_CSV2_3 ?= 0

	# By default, disable access of trace system registers from NS lower
	# ELs i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused if
	# system register trace is implemented. This feature is available if
	# trace unit such as ETMv4.x, This feature is OPTIONAL and is only
	# permitted in Armv8 implementations.
	ENABLE_SYS_REG_TRACE_FOR_NS ?= 0

	#----
	# 8.2
	#----

	# Build option to enable/disable the Statistical Profiling Extension,
	# keep it enabled by default for AArch64.
	ifeq (${ARCH},aarch64)
	ENABLE_SPE_FOR_NS ?= 2
	else ifeq (${ARCH},aarch32)
	ifneq ($(or $(ENABLE_SPE_FOR_NS),0),0)
	$(error ENABLE_SPE_FOR_NS is not supported for AArch32)
	else
	ENABLE_SPE_FOR_NS := 0
	endif
	endif

	# Enable SVE for non-secure world by default.
	ifeq (${ARCH},aarch64)
	ENABLE_SVE_FOR_NS ?= 2
	# SVE is only supported on AArch64 so disable it on AArch32.
	else ifeq (${ARCH},aarch32)
	ifneq ($(or $(ENABLE_SVE_FOR_NS),0),0)
	$(error ENABLE_SVE_FOR_NS is not supported for AArch32)
	else
	ENABLE_SVE_FOR_NS := 0
	endif
	endif

	#----
	# 8.4
	#----

	# Feature flags for supporting Activity monitor extensions.
	ENABLE_FEAT_AMU ?= 0
	ENABLE_AMU_AUXILIARY_COUNTERS ?= 0
	ENABLE_AMU_FCONF ?= 0
	AMU_RESTRICT_COUNTERS ?= 0

	# Build option to enable MPAM for lower ELs.
	# Enabling it by default
	ifeq (${ARCH},aarch64)
	ENABLE_FEAT_MPAM ?= 2
	else ifeq (${ARCH},aarch32)
	ifneq ($(or $(ENABLE_FEAT_MPAM),0),0)
	$(error ENABLE_FEAT_MPAM is not supported for AArch32)
	else
	ENABLE_FEAT_MPAM := 0
	endif
	endif

	# Include nested virtualization control (Armv8.4-NV) registers in cpu context.
	# This must be set to 1 if architecture implements Nested Virtualization
	# Extension and platform wants to use this feature in the Secure world.
	CTX_INCLUDE_NEVE_REGS ?= 0

	#----
	# 8.5
	#----

	# Flag to enable support for EL3 trapping of reads of the RNDR and RNDRRS
	# registers, by setting SCR_EL3.TRNDR.
	ENABLE_FEAT_RNG_TRAP ?= 0

	# Enable Memory Tagging Extension. This must be set to 1 if the platform wants
	# to use this feature in the Secure world and MTE is enabled at ELX.
	ifeq ($(CTX_INCLUDE_MTE_REGS),1)
	$(warning CTX_INCLUDE_MTE_REGS option is deprecated use ENABLE_FEAT_MTE, Enabling ENABLE_FEAT_MTE)
	ENABLE_FEAT_MTE ?= 1
	endif
	ifeq (${ARCH},aarch32)
	ifneq ($(or $(ENABLE_FEAT_MTE),0),0)
	$(error ENABLE_FEAT_MTE is not supported for AArch32)
	endif
	endif
	ENABLE_FEAT_MTE ?= 0

	#----
	# 8.6
	#----

	# Flag to enable AMUv1p1 extension.
	ENABLE_FEAT_AMUv1p1 ?= 0

	# Flag to enable delayed trapping of WFE instruction (FEAT_TWED).
	ENABLE_FEAT_TWED ?= 0

	# In v8.6+ platforms with delayed trapping of WFE being supported
	# via FEAT_TWED, this flag takes the delay value to be set in the
	# SCR_EL3.TWEDEL(4bit) field, when FEAT_TWED is implemented.
	# By default it takes 0, and need to be updated by the platforms.
	TWED_DELAY ?= 0

	# Disable MTPMU if FEAT_MTPMU is supported.
	DISABLE_MTPMU ?= 0

	#----
	# 8.9
	#----

	# Flag to enable NoTagAccess memory region attribute for stage 2 of translation.
	ENABLE_FEAT_MTE_PERM ?= 0

	# Flag to enable access to Stage 2 Permission Indirection (FEAT_S2PIE).
	ENABLE_FEAT_S2PIE ?= 0

	# Flag to enable access to Stage 1 Permission Indirection (FEAT_S1PIE).
	ENABLE_FEAT_S1PIE ?= 0

	# Flag to enable access to Stage 2 Permission Overlay (FEAT_S2POE).
	ENABLE_FEAT_S2POE ?= 0

	# Flag to enable access to Stage 1 Permission Overlay (FEAT_S1POE).
	ENABLE_FEAT_S1POE ?= 0

	#----
	# 9.0
	#----

	# Flag to enable Realm Management Extension (FEAT_RME).
	ENABLE_RME ?= 0

	# Scalable Matrix Extension for non-secure world.
	ENABLE_SME_FOR_NS ?= 0

	# Scalable Vector Extension for secure world.
	ENABLE_SVE_FOR_SWD ?= 0

	# By default, disable access of trace buffer control registers from NS
	# lower ELs i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused
	# if FEAT_TRBE is implemented.
	# Note FEAT_TRBE is only supported on AArch64 - therefore do not enable in
	# AArch32.
	ifeq (${ARCH},aarch64)
	ENABLE_TRBE_FOR_NS ?= 0
	else ifeq (${ARCH},aarch32)
	ifneq ($(or $(ENABLE_TRBE_FOR_NS),0),0)
	$(error ENABLE_TRBE_FOR_NS is not supported for AArch32)
	else
	ENABLE_TRBE_FOR_NS := 0
	endif
	endif

	#----
	# 9.2
	#----

	# Scalable Matrix Extension version 2 for non-secure world.
	ENABLE_SME2_FOR_NS ?= 0

	# Scalable Matrix Extension for secure world.
	ENABLE_SME_FOR_SWD ?= 0

	# By default, disable access to branch record buffer control registers from NS
	# lower ELs i.e. NS-EL2, or NS-EL1 if NS-EL2 implemented but unused
	# if FEAT_BRBE is implemented.
	ENABLE_BRBE_FOR_NS ?= 0

	#----
	#9.4
	#----

	# Flag to enable access to Guarded Control Stack (FEAT_GCS).
	ENABLE_FEAT_GCS ?= 0