esp-idf/Kconfig

#
# For a description of the syntax of this configuration file,
# see kconfig/kconfig-language.txt.
#
mainmenu "Espressif IoT Development Framework Configuration"

    # Hidden option to support checking for this specific target in C code and Kconfig files
    config IDF_TARGET_ESP32
        bool
        default "y" if IDF_TARGET="esp32"
        default "n"

    config IDF_CMAKE
        bool
        option env="IDF_CMAKE"


    config IDF_TARGET_ENV
        # A proxy to get environment variable $IDF_TARGET
        string
        option env="IDF_TARGET"

    config IDF_TARGET
        # This option records the IDF target when sdkconfig is generated the first time.
        # It is not updated if environment variable $IDF_TARGET changes later, and
        # the build system is responsible for detecting the mismatch between
        # CONFIG_IDF_TARGET and $IDF_TARGET.
        string
        default "IDF_TARGET_NOT_SET" if IDF_TARGET_ENV=""
        default IDF_TARGET_ENV

    config IDF_FIRMWARE_CHIP_ID
        hex
        default 0x0000 if IDF_TARGET="esp32"
        default 0xFFFF

    menu "SDK tool configuration"
        config SDK_TOOLPREFIX
            string "Compiler toolchain path/prefix"
            default "xtensa-esp32-elf-"
            help
                The prefix/path that is used to call the toolchain. The default setting assumes
                a crosstool-ng gcc setup that is in your PATH.

        config SDK_PYTHON
            string "Python 2 interpreter"
            depends on !IDF_CMAKE
            default "python"
            help
                The executable name/path that is used to run python. On some systems Python 2.x
                may need to be invoked as python2.

                (Note: This option is used with the legacy GNU Make build system only.)

        config SDK_MAKE_WARN_UNDEFINED_VARIABLES
            bool "'make' warns on undefined variables"
            depends on !IDF_CMAKE
            default "y"
            help
                Adds --warn-undefined-variables to MAKEFLAGS. This causes make to
                print a warning any time an undefined variable is referenced.

                This option helps find places where a variable reference is misspelled
                or otherwise missing, but it can be unwanted if you have Makefiles which
                depend on undefined variables expanding to an empty string.

                (Note: this option is used with the legacy GNU Make build system only.)

    endmenu  # SDK tool configuration

    menu "Build type"

        choice APP_BUILD_TYPE
            prompt "Application build type"
            default APP_BUILD_TYPE_APP_2NDBOOT
            help
                Select the way the application is built.

                By default, the application is built as a binary file in a format compatible with
                the ESP32 bootloader. In addition to this application, 2nd stage bootloader is
                also built. Application and bootloader binaries can be written into flash and
                loaded/executed from there.

                Another option, useful for only very small and limited applications, is to only link
                the .elf file of the application, such that it can be loaded directly into RAM over
                JTAG. Note that since IRAM and DRAM sizes are very limited, it is not possible to
                build any complex application this way. However for kinds of testing and debugging,
                this option may provide faster iterations, since the application does not need to be
                written into flash.
                Note that at the moment, ESP-IDF does not contain all the startup code required to
                initialize the CPUs and ROM memory (data/bss). Therefore it is necessary to execute
                a bit of ROM code prior to executing the application. A gdbinit file may look as follows:

                    # Connect to a running instance of OpenOCD
                    target remote :3333
                    # Reset and halt the target
                    mon reset halt
                    # Run to a specific point in ROM code,
                    #  where most of initialization is complete.
                    thb *0x40007901
                    c
                    # Load the application into RAM
                    load
                    # Run till app_main
                    tb app_main
                    c

                Execute this gdbinit file as follows:

                    xtensa-esp32-elf-gdb build/app-name.elf -x gdbinit

                Recommended sdkconfig.defaults for building loadable ELF files is as follows.
                CONFIG_APP_BUILD_TYPE_ELF_RAM is required, other options help reduce application
                memory footprint.

                    CONFIG_APP_BUILD_TYPE_ELF_RAM=y
                    CONFIG_VFS_SUPPORT_TERMIOS=
                    CONFIG_NEWLIB_NANO_FORMAT=y
                    CONFIG_ESP32_PANIC_PRINT_HALT=y
                    CONFIG_ESP32_DEBUG_STUBS_ENABLE=
                    CONFIG_ESP_ERR_TO_NAME_LOOKUP=


            config APP_BUILD_TYPE_APP_2NDBOOT
                bool
                prompt "Default (binary application + 2nd stage bootloader)"
                select APP_BUILD_GENERATE_BINARIES
                select APP_BUILD_BOOTLOADER
                select APP_BUILD_USE_FLASH_SECTIONS

            config APP_BUILD_TYPE_ELF_RAM
                bool
                prompt "ELF file, loadable into RAM (EXPERIMENTAL))"
        endchoice # APP_BUILD_TYPE

        # Hidden options, set according to the choice above
        config APP_BUILD_GENERATE_BINARIES
            bool # Whether to generate .bin files or not

        config APP_BUILD_BOOTLOADER
            bool # Whether to build the bootloader

        config APP_BUILD_USE_FLASH_SECTIONS
            bool # Whether to place code/data into memory-mapped flash sections

    endmenu # Build type

    source "$COMPONENT_KCONFIGS_PROJBUILD"

    menu "Compiler options"

        choice COMPILER_OPTIMIZATION
            prompt "Optimization Level"
            default COMPILER_OPTIMIZATION_DEFAULT
            help
                This option sets compiler optimization level (gcc -O argument).

                - The "Default" setting will add the -0g flag to CFLAGS.
                - The "Size" setting will add the -0s flag to CFLAGS.
                - The "Performance" setting will add the -O2 flag to CFLAGS.
                - The "None" setting will add the -O0 flag to CFLAGS.

                The "Size" setting cause the compiled code to be smaller and faster, but
                may lead to difficulties of correlating code addresses to source file
                lines when debugging.

                The "Performance" setting causes the compiled code to be larger and faster,
                but will be easier to correlated code addresses to source file lines.

                "None" with -O0 produces compiled code without optimization.

                Note that custom optimization levels may be unsupported.

            config COMPILER_OPTIMIZATION_DEFAULT
                bool "Debug (-Og)"
            config COMPILER_OPTIMIZATION_SIZE
                bool "Optimize for size (-Os)"
            config COMPILER_OPTIMIZATION_PERF
                bool "Optimize for performance (-O2)"
            config COMPILER_OPTIMIZATION_NONE
                bool "Debug without optimization (-O0)"

        endchoice

        choice COMPILER_OPTIMIZATION_ASSERTION_LEVEL
            prompt "Assertion level"
            default COMPILER_OPTIMIZATION_ASSERTIONS_ENABLE
            help
                Assertions can be:

                - Enabled. Failure will print verbose assertion details. This is the default.

                - Set to "silent" to save code size (failed assertions will abort() but user
                  needs to use the aborting address to find the line number with the failed assertion.)

                - Disabled entirely (not recommended for most configurations.) -DNDEBUG is added
                  to CPPFLAGS in this case.

            config COMPILER_OPTIMIZATION_ASSERTIONS_ENABLE
                prompt "Enabled"
                bool
                help
                    Enable assertions. Assertion content and line number will be printed on failure.

            config COMPILER_OPTIMIZATION_ASSERTIONS_SILENT
                prompt "Silent (saves code size)"
                bool
                help
                    Enable silent assertions. Failed assertions will abort(), user needs to
                    use the aborting address to find the line number with the failed assertion.

            config COMPILER_OPTIMIZATION_ASSERTIONS_DISABLE
                prompt "Disabled (sets -DNDEBUG)"
                bool
                help
                    If assertions are disabled, -DNDEBUG is added to CPPFLAGS.

        endchoice # assertions

        menuconfig COMPILER_CXX_EXCEPTIONS
            bool "Enable C++ exceptions"
            default n
            help
                Enabling this option compiles all IDF C++ files with exception support enabled.

                Disabling this option disables C++ exception support in all compiled files, and any libstdc++ code
                which throws an exception will abort instead.

                Enabling this option currently adds an additional ~500 bytes of heap overhead
                when an exception is thrown in user code for the first time.

        config COMPILER_CXX_EXCEPTIONS_EMG_POOL_SIZE
            int "Emergency Pool Size"
            default 0
            depends on COMPILER_CXX_EXCEPTIONS
            help
                Size (in bytes) of the emergency memory pool for C++ exceptions. This pool will be used to allocate
                memory for thrown exceptions when there is not enough memory on the heap.

        choice COMPILER_STACK_CHECK_MODE
            prompt "Stack smashing protection mode"
            default COMPILER_STACK_CHECK_MODE_NONE
            help
                Stack smashing protection mode. Emit extra code to check for buffer overflows, such as stack
                smashing attacks. This is done by adding a guard variable to functions with vulnerable objects.
                The guards are initialized when a function is entered and then checked when the function exits.
                If a guard check fails, program is halted. Protection has the following modes:

                - In NORMAL mode (GCC flag: -fstack-protector) only functions that call alloca, and functions with
                  buffers larger than 8 bytes are protected.

                - STRONG mode (GCC flag: -fstack-protector-strong) is like NORMAL, but includes additional functions
                  to be protected -- those that have local array definitions, or have references to local frame
                  addresses.

                - In OVERALL mode (GCC flag: -fstack-protector-all) all functions are protected.

                Modes have the following impact on code performance and coverage:

                - performance: NORMAL > STRONG > OVERALL

                - coverage: NORMAL < STRONG < OVERALL


            config COMPILER_STACK_CHECK_MODE_NONE
                bool "None"
            config COMPILER_STACK_CHECK_MODE_NORM
                bool "Normal"
            config COMPILER_STACK_CHECK_MODE_STRONG
                bool "Strong"
            config COMPILER_STACK_CHECK_MODE_ALL
                bool "Overall"
        endchoice

        config COMPILER_STACK_CHECK
            bool
            default !COMPILER_STACK_CHECK_MODE_NONE
            help
                Stack smashing protection.

        config COMPILER_WARN_WRITE_STRINGS
            bool "Enable -Wwrite-strings warning flag"
            default "n"
            help
                Adds -Wwrite-strings flag for the C/C++ compilers.

                For C, this gives string constants the type ``const char[]`` so that
                copying the address of one into a non-const ``char *`` pointer
                produces a warning. This warning helps to find at compile time code
                that tries to write into a string constant.

                For C++, this warns about the deprecated conversion from string
                literals to ``char *``.

        config COMPILER_DISABLE_GCC8_WARNINGS
            bool "Disable new warnings introduced in GCC 6 - 8"
            default "n"
            help
                Enable this option if using GCC 6 or newer, and wanting to disable warnings which don't appear with
                GCC 5.


    endmenu # Compiler Options

    menu "Component config"
        source "$COMPONENT_KCONFIGS"
    endmenu

    menu "Compatibility options"
        config LEGACY_INCLUDE_COMMON_HEADERS
            bool "Include headers accross components as before IDF v4.0"
            default n
            help
                Soc, esp32, and driver components, the most common
                components. Some header of these components are included
                implicitly by headers of other components before IDF v4.0.
                It's not required for high-level components, but still
                included through long header chain everywhere.

                This is harmful to the modularity. So it's changed in IDF
                v4.0.

                You can still include these headers in a legacy way until it
                is totally deprecated by enable this option.

    endmenu #Compatibility options