This option instructs the linker to generate code for the 20-bit MSP430X CPU core rather than a 16-bit MSP430 core. Note that it is not possible to mix code generated for the MSP430X with code generated for the MSP430.

By default the linker selects large model when compiling code for an MSP430X. If your target processor has an MSP430X core with a total memory space of less than 64K, you will use less code and data space, and decrease execution time, if you select the compact memory model with the -m64k switch.