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Rename src/Makefile to src/Make.defs and Modify
This item pertains only to custom boards that are developed in-tree, meaning under the NuttX boards/ subdirectory. Out-of-tree boards are not affected.
If your custom board directory is in-tree and in a board family that uses a 'boards/ARCH/FAMILY/common' directory (such as boards/arm/stm32/common, boards/arm/cxd56xx/common, etc), then you'll need to make two minor changes to your custom board's src/Makefile:
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