This is the repository for building a RISC-V Linux binary for BlackParrot. We use Buildroot to generate a BusyBox root filesystem and we use OpenSBI as the machine-mode firmware. The following commands are run within this directory.

make linux.riscv [WITH_SHELL=<path_to_sh_script>] [OPENSBI_NCPUS=<n>] [MEM_SIZE=<s>]

• OPENSBI_NCPUS: Number of harts that boot linux (default: 1)
• WITH_SHELL: If set, at the end of the boot, runs the given shell script instead of creating the BusyBox login shell.
• MEM_SIZE: size in MB of memory (default: 64), sets memory size in device tree; current BP max is 2048

default login: user="root", password=""

The build order is [Buildroot -> sysroot generation -> Linux -> OpenSBI], so each step can be done seperately in the following order:

make buildroot
make sysroot [WITH_SHELL=<path_to_sh_script>]
make vmlinux
make opensbi [OPENSBI_NCPUS=<n>]

To add your custom binaries and files to the root filesystem:

• First, generate the work/sysroot directory by running make sysroot.
• Next, add the binaries to the work/sysroot directory.
• Finally, proceed with the linux and opensbi build by running make linux.riscv.

Example: Adding custom binaries to a quad-core SMP Linux with user terminal:

make sysroot
cp <binaries> work/sysroot/bin/.
make linux.riscv OPENSBI_NCPUS=4

The following commands can be used to clean the work directory. Cleaning each step also wipes the next steps.

make clean
make clean_buildroot
make clean_sysroot
make clean_vmlinux
make clean_opensbi

For example, to rebuild linux for a different OPENSBI_NCPUS value you can wipe the opensbi build and rebuild with the new number of cores:

make clean_opensbi
make linux.riscv OPENSBI_NCPUS=<new_n>

Or to change the initial shell script, you can wipe the sysroot folder and regenerate it with the new script:

make clean_sysroot
make linux.riscv WITH_SHELL=<new_shell>