Linux/RISC-V

This is a port of Linux kernel for the RISC-V instruction set architecture. Development is currently based on the 3.14 longterm branch.

Building the kernel image

1. Fetch upstream sources and overlay the riscv architecture-specific subtree:

    $ curl -L https://www.kernel.org/pub/linux/kernel/v3.x/linux-3.14.41.tar.xz | tar -xJ
    $ cd linux-3.14.41
    $ git init
    $ git remote add origin https://github.com/riscv/riscv-linux.git
    $ git fetch
    $ git checkout -f -t origin/master
   

2. Populate ./.config with the default symbol values:

    $ make ARCH=riscv defconfig
   

3. Optionally edit the configuration via an ncurses interface:

    $ make ARCH=riscv menuconfig
   

4. Build the uncompressed kernel image:

    $ make ARCH=riscv -j vmlinux
   

5. Boot the kernel in the functional simulator, optionally specifying a raw disk image for the root filesystem:

    $ spike +disk=path/to/root.img bbl vmlinux
   

   bbl (the Berkeley Boot Loader) is available from the riscv-pk repository.

Exporting kernel headers

The riscv-gnu-toolchain repository includes a copy of the kernel header files. If the userspace API has changed, export the updated headers to the riscv-gnu-toolchain source directory:

$ make ARCH=riscv headers_check
$ make ARCH=riscv INSTALL_HDR_PATH=path/to/riscv-gnu-toolchain/linux-headers headers_install

Rebuild riscv64-unknown-linux-gnu-gcc with the linux target:

$ cd path/to/riscv-gnu-toolchain
$ make linux