Bist du sicher, dass dein mspgcc up-to-date ist? Laut mspgcc-Webseite
sollte er 64 Bit können:
"The mspgcc port of the GNU C compiler is currently based on version
3.2.3 of GNU GCC. It supports all the current variants of the MSP430
processor, and comes with a full set of header files for the
processors, and a basic 'libc' library. Signed and unsigned integers
of 8, 16, 32, and 64 bit lengths are supported. Floating point is
supported, but only for single precision floating values
- no double precision."