Linux kernel for StarFive's JH7100 RISC-V SoC

What is this?

The JH7100 is a Linux-capable dual-core 64bit RISC-V SoC and this tree is meant to collect all the in-development patches for running Linux on boards using this. So far there are two such boards and both are supported by this tree:

1. StarFive VisionFive
2. BeagleV Starlight Beta

The VisionFive boards aren't quite shipping yet, but you can already register interest and ask questions on the forum.

About 300 BeagleV Starlight Beta boards were sent out to developers in April 2021 in preparation for an eventual BeagleV branded board using the updated JH7110 chip. The BeagleBoard organization has since cancelled that project though.

Cross-compiling

Cross-compiling the Linux kernel is surprisingly easy since it doesn't depend on any (target) libraries and most distributions already have packages with a working cross-compiler. We'll also need a few other tools to build everything:

# Debian/Ubuntu
sudo apt-get install libncurses-dev libssl-dev bc flex bison make gcc gcc-riscv64-linux-gnu
# Fedora
sudo dnf install ncurses-devel openssl openssl-devel bc flex bison make gcc gcc-riscv64-linux-gnu
# Archlinux
sudo pacman -S --needed ncurses openssl bc flex bison make gcc riscv64-linux-gnu-gcc

The build system needs to know that we want to cross-compile a kernel for RISC-V by setting ARCH=riscv. It also needs to know the prefix of our cross-compiler using CROSS_COMPILE=riscv64-linux-gnu-. Also let's assume we're building on an 8-core machine so compilation can be greatly sped up by telling make to use all 8 cores with -j8.

First we need to configure the kernel though. Linux has a very extensive configuration system, but you can get a good baseline configuration for the boards using:

make -j8 ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- visionfive_defconfig

There is nothing magic about this configuration other than it has all the drivers enabled that are working for the hardware on the boards. In fact it has very little extra features enabled which is great for compile times, but you are very much encouraged to add additional drivers and configure your kernel further using

make -j8 ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- nconfig

Now compile the whole thing with

make -j8 ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu-

Installing

Once the build has finished the resulting kernel can be found at

arch/riscv/boot/Image

You'll also need the matching device tree at

arch/riscv/boot/dts/starfive/jh7100-starfive-visionfive-v1.dtb

(If you have a Starlight board you should instead be using jh7100-beaglev-starlight.dtb.)

These two files should be copied to the boot partition on the SD card. In the default Fedora image this is /dev/mmcblk0p3 and is mounted at /boot.

Now add the following entry to the grub.cfg file:

menuentry 'My New Kernel' {
    linux /Image earlycon console=ttyS0,115200n8 stmmac.chain_mode=1 root=/dev/mmcblk0p4 rootwait
    devicetree /jh7100-starfive-visionfive-v1.dtb
}

This assumes your root file system is at /dev/mmcblk0p4 which it is in the default Fedora image.

The visionfive_defconfig doesn't enable modules, but if you enabled them in your build you'll also need to install them in /lib/modules/ on the root file system. How to do that best is out of scope for this README though.

Status

SoC

• Clock tree
• Resets
• Pinctrl/Pinmux
• GPIO
• Serial port
• I2C
• SPI
• MMC / SDIO / SD card
• Random number generator
• Temperature sensor
• Ethernet, though stmmac.chain_mode=1 needed on the cmdline
• USB, USB 3.0 is broken with CONFIG_PM=y
• DRM driver
• NVDLA
• Watchdog
• PWM DAC for sound through the minijack, only 16kHz samplerate for now
• I2S [WIP]
• TDM [WIP]
• MIPI-DSI [WIP]
• MIPI-CSI [WIP]
• ISP [WIP]
• Video Decode [WIP]
• Video Encode [WIP]
• QSPI
• Security Engine
• NNE50
• Vision DSP

Board

• LED
• PMIC / Reboot
• Ethernet PHY
• HDMI
• AP6236 Wifi
• AP6236 Bluetooth, with a userspace tool
• I2C EEPROM (VisionFive only)
• GD25LQ128DWIG (VisionFive) / GD25LQ256D (Starlight) flash

Contributing

If you're working on cleaning up or upstreaming some of this or adding support for more of the SoC I'd very much like to incorporate it into this tree. Either send a pull request, mail or contact Esmil on IRC/Slack.

Also think of this tree mostly as a collection of patches that will hopefully mature enough to be submitted upstream eventually. So expect regular rebases.