xref: /Zephyr-latest/arch/arm/core/Kconfig

# ARM core configuration options

# Copyright (c) 2015 Wind River Systems, Inc.
# SPDX-License-Identifier: Apache-2.0

config CPU_CORTEX_M
	bool
	select CPU_CORTEX
	select ARCH_HAS_CUSTOM_SWAP_TO_MAIN
	select HAS_CMSIS_CORE
	select HAS_FLASH_LOAD_OFFSET
	select ARCH_HAS_SINGLE_THREAD_SUPPORT
	select ARCH_HAS_THREAD_ABORT
	select ARCH_HAS_TRUSTED_EXECUTION if ARM_TRUSTZONE_M
	select ARCH_HAS_STACK_PROTECTION if (ARM_MPU && !ARMV6_M_ARMV8_M_BASELINE) || CPU_CORTEX_M_HAS_SPLIM
	select ARCH_HAS_USERSPACE if ARM_MPU
	select ARCH_HAS_NOCACHE_MEMORY_SUPPORT if ARM_MPU && CPU_HAS_ARM_MPU && CPU_HAS_DCACHE
	select ARCH_HAS_RAMFUNC_SUPPORT
	select ARCH_HAS_NESTED_EXCEPTION_DETECTION
	select SWAP_NONATOMIC
	select ARCH_HAS_EXTRA_EXCEPTION_INFO
	select ARCH_HAS_TIMING_FUNCTIONS if CPU_CORTEX_M_HAS_DWT
	select ARCH_SUPPORTS_ARCH_HW_INIT
	select ARCH_HAS_SUSPEND_TO_RAM
	select ARCH_HAS_CODE_DATA_RELOCATION
	select ARCH_SUPPORTS_ROM_START
	imply XIP
	help
	  This option signifies the use of a CPU of the Cortex-M family.

config CPU_AARCH32_CORTEX_R
	bool
	select CPU_CORTEX
	select HAS_CMSIS_CORE
	select ARCH_HAS_NESTED_EXCEPTION_DETECTION
	select HAS_FLASH_LOAD_OFFSET
	select ARCH_HAS_USERSPACE if ARM_MPU && !USE_SWITCH
	select ARCH_HAS_EXTRA_EXCEPTION_INFO if !USE_SWITCH
	select ARCH_HAS_CODE_DATA_RELOCATION
	select ARCH_HAS_NOCACHE_MEMORY_SUPPORT if ARM_MPU && CPU_HAS_ARM_MPU && CPU_HAS_DCACHE
	select ARCH_SUPPORTS_ROM_START
	select USE_SWITCH_SUPPORTED
	help
	  This option signifies the use of a CPU of the Cortex-R family.

config ARM_ZIMAGE_HEADER
	bool "zImage Header"
	depends on CPU_AARCH32_CORTEX_R || CPU_AARCH32_CORTEX_A || CPU_CORTEX_M_HAS_VTOR
	help
	  This option adds a zImage Header.

config CPU_AARCH32_CORTEX_A
	bool
	select CPU_CORTEX
	select CPU_HAS_MMU
	select HAS_CMSIS_CORE
	select HAS_FLASH_LOAD_OFFSET
	select ARCH_HAS_EXTRA_EXCEPTION_INFO if !USE_SWITCH
	select ARCH_HAS_NOCACHE_MEMORY_SUPPORT
	select USE_SWITCH_SUPPORTED
	# GDBSTUB has not yet been tested on Cortex M or R SoCs
	select ARCH_HAS_GDBSTUB
	# GDB on ARM needs the extra registers
	select EXTRA_EXCEPTION_INFO if GDBSTUB
	help
	  This option signifies the use of a CPU of the Cortex-A family.

config GDBSTUB_BUF_SZ
	# GDB for ARM expects up to 18 4-byte plus 8 12-byte
	# registers - 336 HEX letters
	default 350 if GDBSTUB

config ISA_THUMB2
	bool
	help
	  From: http://www.arm.com/products/processors/technologies/instruction-set-architectures.php

	  Thumb-2 technology is the instruction set underlying the ARM Cortex
	  architecture which provides enhanced levels of performance, energy
	  efficiency, and code density for a wide range of embedded
	  applications.

	  Thumb-2 technology builds on the success of Thumb, the innovative
	  high code density instruction set for ARM microprocessor cores, to
	  increase the power of the ARM microprocessor core available to
	  developers of low cost, high performance systems.

	  The technology is backwards compatible with existing ARM and Thumb
	  solutions, while significantly extending the features available to
	  the Thumb instructions set. This allows more of the application to
	  benefit from the best in class code density of Thumb.

	  For performance optimized code Thumb-2 technology uses 31 percent
	  less memory to reduce system cost, while providing up to 38 percent
	  higher performance than existing high density code, which can be used
	  to prolong battery-life or to enrich the product feature set. Thumb-2
	  technology is featured in the  processor, and in all ARMv7
	  architecture-based processors.

config ISA_ARM
	bool
	help
	  From: https://developer.arm.com/products/architecture/instruction-sets/a32-and-t32-instruction-sets

	  A32 instructions, known as Arm instructions in pre-Armv8 architectures,
	  are 32 bits wide, and are aligned on 4-byte boundaries. A32 instructions
	  are supported by both A-profile and R-profile architectures.

	  A32 was traditionally used in applications requiring the highest
	  performance, or for handling hardware exceptions such as interrupts and
	  processor start-up. Much of its functionality was subsumed into T32 with
	  the introduction of Thumb-2 technology.

config ASSEMBLER_ISA_THUMB2
	bool
	default y if ISA_THUMB2 && !ISA_ARM
	depends on !ISA_ARM
	help
	  This helper symbol specifies the default target instruction set for
	  the assembler.

	  When only the Thumb-2 ISA is supported (i.e. on Cortex-M cores), the
	  assembler must use the Thumb-2 instruction set.

	  When both the Thumb-2 and ARM ISAs are supported (i.e. on Cortex-A
	  and Cortex-R cores), the assembler must use the ARM instruction set
	  because the architecture assembly code makes use of the ARM
	  instructions.

config COMPILER_ISA_THUMB2
	bool "Compile C/C++ functions using Thumb-2 instruction set"
	depends on ISA_THUMB2
	default y
	help
	  This option configures the compiler to compile all C/C++ functions
	  using the Thumb-2 instruction set.

	  N.B. The scope of this symbol is not necessarily limited to the C and
	       C++ languages; in fact, this symbol refers to all forms of
	       "compiled" code.

	       When an additional natively-compiled language support is added
	       in the future, this symbol shall also specify the Thumb-2
	       instruction set for that language.

config NUM_IRQS
	int

config STACK_ALIGN_DOUBLE_WORD
	bool "Align stacks on double-words (8 octets)"
	default y
	help
	  This is needed to conform to AAPCS, the procedure call standard for
	  the ARM. It wastes stack space. The option also enforces alignment
	  of stack upon exception entry on Cortex-M3 and Cortex-M4 (ARMv7-M).
	  Note that for ARMv6-M, ARMv8-M, and Cortex-M7 MCUs stack alignment
	  on exception entry is enabled by default and it is not configurable.

config RUNTIME_NMI
	bool "Attach an NMI handler at runtime"
	select REBOOT
	help
	  The kernel provides a simple NMI handler that simply hangs in a tight
	  loop if triggered. This fills the requirement that there must be an
	  NMI handler installed when the CPU boots. If a custom handler is
	  needed, enable this option and attach it via z_arm_nmi_set_handler().

config PLATFORM_SPECIFIC_INIT
	bool "Platform (SOC) specific startup hook [DEPRECATED]"
	select DEPRECATED
	help
	  The platform specific initialization code (z_arm_platform_init) is
	  executed at the beginning of the startup code (__start).

	  This option is deprecated, use SOC_RESET_HOOK instead.

config FAULT_DUMP
	int "Fault dump level"
	default 2
	range 0 2
	help
	  Different levels for display information when a fault occurs.

	  2: The default. Display specific and verbose information. Consumes
		the most memory (long strings).

	  1: Display general and short information. Consumes less memory
		(short strings).

	  0: Off.

config BUILTIN_STACK_GUARD
	bool "Thread Stack Guards based on built-in ARM stack limit checking"
	depends on CPU_CORTEX_M_HAS_SPLIM
	select THREAD_STACK_INFO
	help
	  Enable Thread/Interrupt Stack Guards via built-in Stack Pointer
	  limit checking. The functionality must be supported by HW.

config ARM_STACK_PROTECTION
	bool
	default y if HW_STACK_PROTECTION
	imply BUILTIN_STACK_GUARD if CPU_CORTEX_M_HAS_SPLIM
	select MPU_STACK_GUARD if (!BUILTIN_STACK_GUARD && ARM_MPU)
	help
	  This option enables either:
	  - The built-in Stack Pointer limit checking, or
	  - the MPU-based stack guard
	  to cause a system fatal error
	  if the bounds of the current process stack are overflowed.
	  The two stack guard options are mutually exclusive. The
	  selection of the built-in Stack Pointer limit checking is
	  prioritized over the MPU-based stack guard. The developer
	  still has the option to manually select the MPU-based
	  stack guard, if this is desired.

config ARM_SECURE_FIRMWARE
	bool
	depends on ARMV8_M_SE
	default y if TRUSTED_EXECUTION_SECURE
	help
	  This option indicates that we are building a Zephyr image that
	  is intended to execute in Secure state. The option is only
	  applicable to ARMv8-M MCUs that implement the Security Extension.

	  This option enables Zephyr to include code that executes in
	  Secure state, as well as to exclude code that is designed to
	  execute only in Non-secure state.

	  Code executing in Secure state has access to both the Secure
	  and Non-Secure resources of the Cortex-M MCU.

	  Code executing in Non-Secure state may trigger Secure Faults,
	  if Secure MCU resources are accessed from the Non-Secure state.
	  Secure Faults may only be handled by code executing in Secure
	  state.

config ARM_NONSECURE_FIRMWARE
	bool
	depends on !ARM_SECURE_FIRMWARE
	depends on ARMV8_M_SE
	default y if TRUSTED_EXECUTION_NONSECURE
	help
	  This option indicates that we are building a Zephyr image that
	  is intended to execute in Non-Secure state. Execution of this
	  image is triggered by Secure firmware that executes in Secure
	  state. The option is only applicable to ARMv8-M MCUs that
	  implement the Security Extension.

	  This option enables Zephyr to include code that executes in
	  Non-Secure state only, as well as to exclude code that is
	  designed to execute only in Secure state.

	  Code executing in Non-Secure state has no access to Secure
	  resources of the Cortex-M MCU, and, therefore, it shall avoid
	  accessing them.

config ARM_NONSECURE_PREEMPTIBLE_SECURE_CALLS
	bool "Allow secure function calls to be preempted"
	depends on ARM_NONSECURE_FIRMWARE
	help
	  When enabled, this option indicates that preemptible Zephyr
	  threads performing secure function calls, are allowed to be
	  preempted. When disabled, the option indicates that such
	  threads many not be context-switched-out while doing a Secure
	  function call.

config ARM_STORE_EXC_RETURN
	bool
	default y if CPU_CORTEX_M && (FPU_SHARING || ARM_NONSECURE_PREEMPTIBLE_SECURE_CALLS)
	help
	  Store the EXC_RETURN value when switching threads.
	  This is needed when switching between threads that differ in either
	  FPU usage or security domain.

choice
	prompt "Floating point ABI"
	default FP_HARDABI
	depends on FPU

config FP_HARDABI
	bool "Floating point Hard ABI"
	help
	  This option selects the Floating point ABI in which hardware floating
	  point instructions are generated and uses FPU-specific calling
	  conventions.

config FP_SOFTABI
	bool "Floating point Soft ABI"
	help
	  This option selects the Floating point ABI in which hardware floating
	  point instructions are generated but soft-float calling conventions.

endchoice

config FP16
	bool "Half-precision floating point support"
	default y
	help
	  This option enables the half-precision (16-bit) floating point support
	  via the `__fp16` (both IEEE and ARM alternative formats) and the
	  `_Float16` (defined by ISO/IEC TS 18661-3:2015) types.

choice
	prompt "FP16 format"
	default FP16_IEEE
	depends on FP16

config FP16_IEEE
	bool "FP16 IEEE format"
	help
	  This option selects the IEEE 754-2008 format for FP16.  This format can
	  represent normalized values in the range of 2^(-14) to 65504.  There are
	  11 bits of significand precision, approximately 3 decimal digits.

config FP16_ALT
	bool "FP16 ARM alternative format"
	help
	  This option selects the ARM alternative format for FP16.  This
	  representation is similar to the IEEE 754-2008 format, but does not
	  support infinites or NaNs. Instead, the range of exponents is extended,
	  so that this format can represent normalized values in the range of
	  2^(-14) to 131008.

	  Please note that Clang doesn't support the ARM alternative format.

endchoice

rsource "cortex_m/Kconfig"
rsource "cortex_a_r/Kconfig"

rsource "mpu/Kconfig"
rsource "mmu/Kconfig"