ader1990
commented
2 months ago I managed to get a Gentoo RISC-V built, here is the documentation step by step on how to build the image, maybe someone finds it useful.
Need to test it out on my RISC-V board and then see how it can be applied to Flatcar SDK workflow, work in progress. Readme: https://github.com/ader1990/configs/blob/master/gentoo/Readme-RISCV.md
Initial document how-to, the starting point
https://wiki.gentoo.org/wiki/User:Dlan/RISC-V/TH1520#Host_Env_Setup
Install Gentoo upstream on an AMD64 box was done using the script from this folder
prepare the env - install the toolings
emerge dev-vcs/git
emerge app-misc/screenprepare the crossdev repos (instructions from @chewie)
mkdir -p /var/db/repos/crossdev/{metadata,profiles}
echo crossdev > /var/db/repos/crossdev/profiles/repo_name
cat > /var/db/repos/crossdev/metadata/layout.conf <<EOF
masters = gentoo
thin-manifests = true
cache-formats = md5-dict
EOF
cat > /etc/portage/repos.conf/crossdev.conf <<EOF
[crossdev]
priority = 1001
location = /var/db/repos/crossdev
sync-type =
EOFprepare the crossdev env
emerge --ask sys-devel/crossdev
crossdev --target riscv64-unknown-linux-gnubuild uboot
git clone --depth=1 -b th1520 https://github.com/revyos/thead-u-boot u-boot
pushd u-boot
alias rvmake='make ARCH=riscv CROSS_COMPILE=riscv64-unknown-linux-gnu- -j30 '
# use the 16g target for the 16GB RAM board
rvmake distclean && rvmake light_lpi4a_16g_defconfig && rvmake
ls -liath u-boot-with-spl.bin
popdbuild kernel
git clone --depth=1 -b lpi4a https://github.com/revyos/thead-kernel kernel
pushd kernel
rvmake revyos_defconfig
# to fix the pahole issue
emerge -av dev-util/pahole
rvmake Image
ls -liath ./arch/riscv/boot/Image
rvmake modules
ls -liath modules
rvmake dtbs
ls -liath ./arch/riscv/boot/dts/thead/light-lpi4a-16gb.dtb
git clone https://github.com/revyos/opensbi -b th1520-v1.4
pushd opensbi
rvmake PLATFORM=generic FW_PIC=y
ls build/platform/generic/firmware/fw_dynamic.bin
popd
# get the two closed source light_aon_fpga and light_c906_audio from
# https://git.beagleboard.org/beaglev-ahead/xuantie-ubuntu/-/tree/master/bins
# https://lore.kernel.org/buildroot/20230821234359.06008b73@windsurf/T/
# light_aon_fpga.bin: "aon" is an `Always On` fpga binary used for power
# management... If you don't have this, the board will boot, but things
# like cpufreq don't work..
# light_c906_audio.bin: Probably Audio, never really tested it too much...
# this is how a bootfs should look like
# Image light-lpi4a-ddr2G.dtb light_aon_fpga.bin
# fw_dynamic.bin light-lpi4a.dtb light_c906_audio.bin
# kernel-release light-lpi4a_2Ghz.dtb lost+found
popd
chewi
Current situation
Flatcar cannot be built for the RISC-V architecture (https://riscv.org).
Impact
Consumer boards are starting to become widely available, like the Vision 5, LicheePi 4A or Milk-V. Enterprise grade manufacturers like Ventana are also providing server grade RISC-V CPUs. Also, cloud providers like Scaleway already offer RISC-V instances.
Ideal future situation
To be able to run Flatcar on RISC-V systems.
Implementation options
Upstream Gentoo already has support for most of the packages. The SDK needs to be worked on and maybe also streamline / organize the build code for ARM64 and RISC-V at the same time, so that ARM-on-ARM and RISC-on-RISC builds can be possible, without forcing cross-compilation.