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ba1bbaf67d
This is the culmination of months of work to reduce heap churn throughout the ESPHome codebase. By systematically eliminating unnecessary dynamic allocations (StaticVector, FixedVector, const char* instead of std::string, pre-allocated buffers, etc.), heap functions are now called so infrequently that they can safely be moved from IRAM to flash. Enable CONFIG_HEAP_PLACE_FUNCTION_INTO_FLASH by default, which moves malloc/free/realloc from IRAM to flash. This is safe because: - Heap functions should never be called from ISRs - CONFIG_SPI_MASTER_ISR_IN_IRAM is not enabled - Audio/video use pre-allocated ring buffers, not dynamic allocation Measured results: +6,124 bytes of heap freed. Add heap_in_iram advanced option as an escape hatch for users who need heap functions in IRAM for specific use cases.
