The 32bit microprocessor is the point of the design, period, testing it out in the RC truck is just a fun way of utilizing the processor. The purpose of the FPGA is just for prototyping the SOC, and I could use off the self parts to implement this application, (still need the C++ source code, which is the point of the post), but where is the fun in that? I get the most fun out of doing the design myself, implementing it and seeing it work, so there are the reasons why. The joy and fun I get out of doing the design is the motivation.
I've designed the processor so that I can basically use any compiler designed for almost any architecture. So what the compiler really doesn't matter all the programming for the processor can be done at the high level, ie C++ and I can then microprogram the processor to understand and run on the machine code produced by most any compiler. But to answer your question the compiler I'm using now is a GCC mips cross compiler. When you say run on linux what exactly do you mean?