zephyr/misc/Kconfig

# Kconfig - miscellany configuration options

#
# Copyright (c) 2014-2015 Wind River Systems, Inc.
#
# SPDX-License-Identifier: Apache-2.0
#

menu "Compile and Link Features"

menu "Linker Options"
config TEXT_SECTION_OFFSET
	hex "TEXT section offset"
	default 0
	help
	This sets and offset before the text section and allows booting images
	with custom headers that are inserted at the beginning of the image.

config HAVE_CUSTOM_LINKER_SCRIPT
	prompt "Custom linker scripts provided"
	def_bool n
	help
	Set this option if you have a custom linker script which needed to
	be define in CUSTOM_LINKER_SCRIPT.

config CUSTOM_LINKER_SCRIPT
	string "Path to custom linker script"
	default ""
	depends on HAVE_CUSTOM_LINKER_SCRIPT
	help
	Path to the linker script to be used instead of the one define by the
	board.

	The linker script must be based on a version provided by Zephyr since
	the kernel can expect a certain layout/certain regions.

	This is useful when an application needs to add sections into the
	linker script and avoid having to change the script provided by
	Zephyr.

config CUSTOM_RODATA_LD
	bool "Include custom-rodata.ld"
	default n
	help
	Include a customized linker script fragment for inserting additional
	data and linker directives into the rodata section.

config CUSTOM_RWDATA_LD
	bool "Include custom-rwdata.ld"
	default n
	help
	Include a customized linker script fragment for inserting additional
	data and linker directives into the data section.

config CUSTOM_SECTIONS_LD
	bool "Include custom-sections.ld"
	default n
	help
	Include a customized linker script fragment for inserting additional
	arbitrary sections.

config LINK_WHOLE_ARCHIVE
	bool "Allow linking with --whole-archive"
	default n
	help
	This options allows linking external libraries with the
	--whole-archive option to keep all symbols.

endmenu

menu "Compiler Options"
config CROSS_COMPILE
	string "Cross-compiler tool prefix"
	help
	Same as running 'make CROSS_COMPILE=prefix-' but stored for
	default make runs in this kernel build directory.  You don't
	need to set this unless you want the configured kernel build
	directory to select the cross-compiler automatically.

config COMPILER_OPT
	string
	prompt "Custom compiler options"
	default ""
	help
	This option is a free-form string that is passed to the compiler
	when building all parts of a project (i.e. kernel).
	The compiler options specified by this string supplement the
	pre-defined set of compiler supplied by the build system,
	and can be used to change compiler optimization, warning and error
	messages, and so on.

config TOOLCHAIN_VARIANT
	string "Cross-compiler variant name"
	help
	For optimized compilers with reduced features, specify the name
	of the variant.

endmenu

config CPLUSPLUS
	bool "Enable C++ support for the application"
	default n
	help
	This option enables the use of applications built with C++.

config GDB_INFO
	bool
	prompt "Task-aware debugging with GDB"
	default n
	help
	  This option enables the kernel to collect additional information
	  during interrupts, exceptions, and context switches. This information
	  is required for task-aware debugging with GDB.

config KERNEL_BIN_NAME
	string "The kernel binary name"
	default "zephyr"
	help
	This option sets the name of the generated kernel binary.

endmenu

menu "Debugging Options"

config DEBUG
	bool "Build kernel with debugging enabled"
	default n
	help
	Build a kernel suitable for debugging.  Right now, this option
	only disables optimization, more debugging variants can be selected
	from here to allow more debugging.

config STACK_USAGE
	bool "Generate stack usage information"
	default n
	help
	Generate  an extra file that specifies the maximum amount of stack used,
	on a per-function basis.

config PRINTK
	bool
	prompt "Send printk() to console"
	depends on CONSOLE_HAS_DRIVER
	default y
	help
	This option directs printk() debugging output to the supported
	console device, rather than suppressing the generation
	of printk() output entirely. Output is sent immediately, without
	any mutual exclusion or buffering.

config STDOUT_CONSOLE
	bool
	prompt "Send stdout to console"
	depends on CONSOLE_HAS_DRIVER
	default n
	help
	This option directs standard output (e.g. printf) to the console
	device, rather than suppressing it entirely.

config EARLY_CONSOLE
	bool
	prompt "Send stdout at the earliest stage possible"
	default n
	help
	This option will enable stdout as early as possible, for debugging
	purpose. For instance, in case of STDOUT_CONSOLE being set it will
	initialize its driver earlier than normal, in order to get the stdout
	sent through the console at the earliest stage possible.

config ASSERT
	bool
	prompt "Enable __ASSERT() macro"
	default n
	help
	This enables the __ASSERT() macro in the kernel code. If an assertion
	fails, the calling thread is put on an infinite tight loop. Since
	enabling this adds a significant footprint, it should only be enabled
	in a non-production system.

config ASSERT_LEVEL
	int
	prompt "__ASSERT() level"
	default 2
	range 0 2
	depends on ASSERT
	help
	This option specifies the assertion level used by the __ASSERT()
	macro. It can be set to one of three possible values:

	Level 0: off
	Level 1: on + warning in every file that includes __assert.h
	Level 2: on + no warning

config DEBUG_TRACING_KERNEL_OBJECTS
	bool "Kernel object tracing (deprecated)"
	select OBJECT_TRACING
	default n
	help
	  For backward compatibility only

config OBJECT_TRACING
	bool
	prompt "Kernel object tracing"
	default n
	help
	This option enable the feature for tracing kernel objects. This option
	is for debug purposes and increases the memory footprint of the kernel.

config OVERRIDE_FRAME_POINTER_DEFAULT
	bool
	prompt "Override compiler defaults for -fomit-frame-pointer"
	default n
	help
	Omitting the frame pointer prevents the compiler from putting the stack
	frame pointer into a register. Saves a few instructions in function
	prologues/epilogues and frees up a register for general-purpose use,
	which can provide good performance improvements on register-constrained
	architectures like x86. On some architectures (including x86) omitting
	frame pointers impedes debugging as local variables are harder to
	locate. At -O1 and above gcc will enable -fomit-frame-pointer
	automatically but only if the architecture does not require if for
	effective debugging.

	Choose Y is you want to override the default frame pointer behaviour
	of your compiler, otherwise choose N.

config OMIT_FRAME_POINTER
	bool
	prompt "Omit frame pointer"
	default n
	depends on OVERRIDE_FRAME_POINTER_DEFAULT
	help
	Choose Y for best performance. On some architectures (including x86)
	this will favour code size and performance over debugability.

	Choose N in you wish to retain the frame pointer. This option may
	be useful if your application uses runtime backtracing and does not
	support parsing unwind tables.

	If unsure, disable OVERRIDE_FRAME_POINTER_DEFAULT to allow the compiler
	to adopt sensible defaults for your architecture.

endmenu

menu "System Monitoring Options"

config PERFORMANCE_METRICS
	bool
	prompt "Enable performance metrics [EXPERIMENTAL]"
	default n
	help
	Enable Performance Metrics.

config BOOT_TIME_MEASUREMENT
	bool
	prompt "Boot time measurements [EXPERIMENTAL]"
	default n
	depends on PERFORMANCE_METRICS
	help
	This option enables the recording of timestamps during system start
	up. The global variable __start_tsc records the time kernel begins
	executing, while __main_tsc records when main() begins executing,
	and __idle_tsc records when the CPU becomes idle. All values are
	recorded in terms of CPU clock cycles since system reset.

config CPU_CLOCK_FREQ_MHZ
	int
	prompt "CPU CLock Frequency in MHz"
	default 20
	depends on BOOT_TIME_MEASUREMENT
	help
	This option specifies the CPU Clock Frequency in MHz in order to
	convert Intel RDTSC timestamp to microseconds.

endmenu

menu "Boot Options"

config IS_BOOTLOADER
	bool "Act as a bootloader"
	default n
	depends on XIP
	depends on ARM
	help
	This option indicates that Zephyr will act as a bootloader to execute
	a separate Zephyr image payload.

config BOOTLOADER_SRAM_SIZE
	int "SRAM reserved for when Zephyr acts as a bootloader"
	default 16
	depends on !XIP || IS_BOOTLOADER
	depends on ARM
	help
	This option specifies the amount of SRAM (measure in kB) reserved for
	when Zephyr is to act as a bootloader.

config BOOTLOADER_KEXEC
	bool
	prompt "Boot using Linux kexec() system call"
	depends on X86
	default n
	help
	This option signifies that Linux boots the kernel using kexec system call
	and utility. This method is used to boot the kernel over the network.

config BOOTLOADER_UNKNOWN
	bool
	prompt "Generic boot loader support"
	default n
	depends on X86
	help
	This option signifies that the target has a generic bootloader
	or that it supports multiple ways of booting and it isn't clear
	at build time which method is to be used. When this option is enabled
	the board may have to do extra work to ensure a proper startup.

config BOOTLOADER_CONTEXT_RESTORE
	bool
	prompt "Boot loader has context restore support"
	default y
	depends on SYS_POWER_DEEP_SLEEP && BOOTLOADER_CONTEXT_RESTORE_SUPPORTED
	help
	This option signifies that the target has a bootloader
	that restores CPU context upon resuming from deep sleep
	power state.

config REBOOT
	bool "Reboot functionality"
	default n
	select SYSTEM_CLOCK_DISABLE
	help
	Enable the sys_reboot() API. Enabling this can drag in other subsystems
	needed to perform a "safe" reboot (e.g. SYSTEM_CLOCK_DISABLE, to stop the
	system clock before issuing a reset).
endmenu