esp-idf/components/esp_common/Kconfig.spiram.common

# Common (non-chip-specific) SPIRAM options
#
# sourced into the "SPIRAM config" submenu for ESP32 or ESP32S2

# invisible option selected by ESP32_SPIRAM_SUPPORT || ESP32S2_SPIRAM_SUPPORT
config SPIRAM
    bool

config SPIRAM_BOOT_INIT
    bool "Initialize SPI RAM during startup"
    default "y"
    help
        If this is enabled, the SPI RAM will be enabled during initial boot. Unless you
        have specific requirements, you'll want to leave this enabled so memory allocated
        during boot-up can also be placed in SPI RAM.

config SPIRAM_IGNORE_NOTFOUND
    bool "Ignore PSRAM when not found"
    default "n"
    depends on SPIRAM_BOOT_INIT && !SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
    help
        Normally, if psram initialization is enabled during compile time but not found at runtime, it
        is seen as an error making the CPU panic. If this is enabled, booting will complete
        but no PSRAM will be available.

choice SPIRAM_USE
    prompt "SPI RAM access method"
    default SPIRAM_USE_MALLOC
    help
        The SPI RAM can be accessed in multiple methods: by just having it available as an unmanaged
        memory region in the CPU's memory map, by integrating it in the heap as 'special' memory
        needing heap_caps_malloc to allocate, or by fully integrating it making malloc() also able to
        return SPI RAM pointers.

    config SPIRAM_USE_MEMMAP
        bool "Integrate RAM into memory map"
    config SPIRAM_USE_CAPS_ALLOC
        bool "Make RAM allocatable using heap_caps_malloc(..., MALLOC_CAP_SPIRAM)"
    config SPIRAM_USE_MALLOC
        bool "Make RAM allocatable using malloc() as well"
        select FREERTOS_SUPPORT_STATIC_ALLOCATION
endchoice

config SPIRAM_MEMTEST
    bool "Run memory test on SPI RAM initialization"
    default "y"
    depends on SPIRAM_BOOT_INIT
    help
        Runs a rudimentary memory test on initialization. Aborts when memory test fails. Disable this for
        slightly faster startup.

config SPIRAM_MALLOC_ALWAYSINTERNAL
    int "Maximum malloc() size, in bytes, to always put in internal memory"
    depends on SPIRAM_USE_MALLOC
    default 16384
    range 0 131072
    help
        If malloc() is capable of also allocating SPI-connected ram, its allocation strategy will prefer to
        allocate chunks less than this size in internal memory, while allocations larger than this will be
        done from external RAM. If allocation from the preferred region fails, an attempt is made to allocate
        from the non-preferred region instead, so malloc() will not suddenly fail when either internal or
        external memory is full.

config SPIRAM_TRY_ALLOCATE_WIFI_LWIP
    bool "Try to allocate memories of WiFi and LWIP in SPIRAM firstly. If failed, allocate internal memory"
    depends on SPIRAM_USE_CAPS_ALLOC || SPIRAM_USE_MALLOC
    default "n"
    help
        Try to allocate memories of WiFi and LWIP in SPIRAM firstly. If failed, try to allocate internal
        memory then.

config SPIRAM_MALLOC_RESERVE_INTERNAL
    int "Reserve this amount of bytes for data that specifically needs to be in DMA or internal memory"
    depends on SPIRAM_USE_MALLOC
    default 32768
    range 0 262144
    help
        Because the external/internal RAM allocation strategy is not always perfect, it sometimes may happen
        that the internal memory is entirely filled up. This causes allocations that are specifically done in
        internal memory, for example the stack for new tasks or memory to service DMA or have memory that's
        also available when SPI cache is down, to fail. This option reserves a pool specifically for requests
        like that; the memory in this pool is not given out when a normal malloc() is called.

        Set this to 0 to disable this feature.

        Note that because FreeRTOS stacks are forced to internal memory, they will also use this memory pool;
        be sure to keep this in mind when adjusting this value.

        Note also that the DMA reserved pool may not be one single contiguous memory region, depending on the
        configured size and the static memory usage of the app.

config SPIRAM_ALLOW_BSS_SEG_EXTERNAL_MEMORY
    bool "Allow .bss segment placed in external memory"
    default n
    depends on SPIRAM && IDF_TARGET_ESP32 # TODO ESP32-S2 IDFGH-4320
    help
        If enabled the option,and add EXT_RAM_ATTR defined your variable,then your variable will be placed in
        PSRAM instead of internal memory, and placed most of variables of lwip,net802.11,pp,bluedroid library
        to external memory defaultly.