3.3.5.2 How Do I Stop An Unused Function Being Removed?

The __attribute__((keep)) may be applied to a function. The keep attribute will prevent the linker from removing the function with --gc-sections, even if it is unused. See the “MPLAB^® XC32 Assembler, Linker and Utilities User’s Guide” (DS50002186) for more information on section garbage collection using the --gc-sections option.