heap_caps_malloc was called but failed to allocate

[zazas321]

Hello. I have some issues with heap memory allocation. I have started to dig into how it works.

in my code, I have registered failed alloc callback:

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esp_err_t error = heap_caps_register_failed_alloc_callback(heap_caps_alloc_failed_hook);

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void heap_caps_alloc_failed_hook(size_t requested_size, uint32_t caps, const char *function_name) {
    printf("%s was called but failed to allocate %d bytes with %ld capabilities. \n", function_name, requested_size,caps);
}

Occasionally, I can see the following errors pop up in the logs:

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heap_caps_malloc was called but failed to allocate 1696 bytes with 6144 capabilities.

I started looking into malloc function declaration and noticed something strange:

In flash_mock.cpp I have found the following:

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void *heap_caps_malloc( size_t size, uint32_t caps )
{
    return NULL;
}

Is this function deprecated? what is flash_mock.cpp?

In the heap_caps.c I have also found the real heap_caps_malloc function declaration:

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IRAM_ATTR void *heap_caps_malloc( size_t size, uint32_t caps){

    void* ptr = heap_caps_malloc_base(size, caps);

    if (!ptr && size > 0){
        heap_caps_alloc_failed(size, caps, __func__);
    }

    return ptr;
}

[MicroController]

Occasionally, I can see the following errors pop up in the logs:

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heap_caps_malloc was called but failed to allocate 1696 bytes with 6144 capabilities.

This may or may not indicate a problem: heap_caps_malloc_prefer(...) may try multiple allocations which may fail until one succeeds. E.g. if PSRAM is preferred but no external RAM is present, the first attempt (PSRAM) will always fail, but the next attempt (e.g. DRAM) may succeed thus not causing any problems.

Specifically, CAPS = 6144 is "IRAM" + "byte-adresssable", which on an ESP32 is not physically present, as its IRAM is only word-adressable.

what is flash_mock.cpp?

Looks like a mock/stub for (unit-)testing of IDF. Don't bother with it.