Linux Build

This section explains how to build a Linux system for RVComp using RVComp-buildenv.

The following tools are required. Please refer to the Installation Guide.

riscv-gnu-toolchain
Device Tree Compiler

Buildroot is included as a submodule in RVComp-buildenv and does not need to be installed separately.

We have verified Linux kernel version 6.19.5.

RVComp-buildenv

RVComp-buildenv is a standalone build environment for Linux images for RVComp. It bundles Buildroot as a submodule and provides command.sh, which automates the configure and build steps.

Getting the Source

$ git clone https://github.com/archlab-sciencetokyo/RVComp-buildenv.git
$ cd RVComp-buildenv
$ git submodule update --init --recursive

Building

Before building, unset any compiler include-path variables that may interfere with cross-compilation:

$ unset CPATH
$ unset C_INCLUDE_PATH
$ unset CPLUS_INCLUDE_PATH

Run command.sh with the boot method and the path to the RVComp Buildroot external tree. BR2_EXTERNAL is Buildroot’s mechanism for providing external packages and defconfigs outside the Buildroot source tree; pass the RVComp/buildroot/ directory here. The defconfigs (uart_defconfig, mmc_defconfig) specify the Linux kernel version, kernel configuration, package selection, and root filesystem format for each boot method.

Usage: ./command.sh <uart|mmc> <br2_external>

  uart  build uart_defconfig
  mmc   build mmc_defconfig

UART boot:

$ ./command.sh uart /path/to/RVComp/buildroot

MMC boot:

$ ./command.sh mmc /path/to/RVComp/buildroot

Output

The build output is placed under images/:

images/uart/fw_payload.bin: Linux payload for UART boot
images/mmc/fw_payload.bin: Combined image (fw_payload.bin padded to 32 MiB followed by rootfs.ext4), ready to write to a microSD card

UART boot:

Copy fw_payload.bin to RVComp/image/, then rebuild the bitstream:

$ cp images/uart/fw_payload.bin /path/to/RVComp/image/fw_payload.bin
$ cd /path/to/RVComp
$ make bit

Update BIN_SIZE in config.mk with the actual file size before running make bit:

$ stat images/uart/fw_payload.bin   # read the Size: field

MMC boot:

Write the combined image to a microSD card, set BIN_SIZE to 32 MiB in config.mk, then rebuild the bitstream:

$ sudo dd if=images/mmc/fw_payload.bin of=/dev/sdX bs=1M conv=fsync,notrunc status=progress
$ cd /path/to/RVComp
$ make bit

Set BIN_SIZE = 33554432 (32 MiB) in config.mk before running make bit. See Setup Before Make Command for details.

Kernel Modules and Boot Files

For details on the RVComp-specific kernel modules (rvcomp-ethernet, rvcomp-mmc) and boot scripts (rvcomp-bootfiles) included in the Buildroot packages, see Device Drivers.