1. Download and install toolchain
$ curl https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.3.0-2019.08.0-x86_64-linux-ubuntu14.tar.gz
2. Build and install qemu
$ git clone https://github.com/qemu/qemu
$ cd qemu
$ ./configure --target-list=riscv32-softmmu,riscv64-softmmu
$ make
$ sudo make install
3. Configure and build NuttX
$ mkdir ./nuttx; cd ./nuttx
$ git clone https://github.com/apache/incubator-nuttx.git
$ git clone https://github.com/apache/incubator-nuttx-apps.git
$ cd nuttx
$ make distclean
$ ./tools/configure.sh rv-virt:nsh
$ make
4. Run the nuttx with qemu
$ qemu-system-riscv32 -M virt -cpu rv32 -smp 8 -bios none -kernel nuttx -nographic
or
$ qemu-system-riscv64 -M virt -cpu rv64 -smp 8-bios none -kernel nuttx -nographic
5. TODO
Support FPU
Support RISC-V User mode
Support Network