I've posted what I hope are useful instructions for compiling C and C++ applications for P2 using a RISC-V toolchain. The repository is at https://github.com/totalspectrum/riscvp2
. The README.md should describe everything you need, including where to find a pre-built RISC-V toolchain. Once your RISC-V toolchain is installed, edit the Makefile to have the correct paths and then do "make install". That should update your RISC-V toolchain so that it can build P2 binaries as well, by just giving the "-T riscvp2.ld" switch to riscv-none-embed-gcc or riscv-none-embed-g++.
"make hello-c++.binary" will build a simple C++ demo application that should run on the P2 Eval board (it works for me, at least!)
Feedback is very welcome. I've been using this kind of setup for a while, so I may well have overlooked some step in the descriptions, or perhaps not made something as clear as it should be. If so, please let me know!
(Tested on Debian Linux. It should work the same for any Linux or Mac OSX. For Windows it *should* work if you have some kind of POSIX system like msys or cygwin installed, but I haven't actually tested it there.)