Kendryte K230 virt reference platform (`k230`)

The k230 machine is compatible with the Kendryte K230 SDK.

The K230 is a chip from the AIoT SoC series made by Kendryte ® — a part of Canaan Inc. It uses a brand-new multi-heterogeneous unit accelerated computing structure.

This chip has 2 RISC-V computing cores and a new-generation KPU (Knowledge Process Unit) smart computing unit.

For more information, see <https://www.kendryte.com/en/proDetail/230>

Supported devices

The k230 machine supports the following devices:

1 c908 cores (little core)
Core Local Interruptor (CLINT)
Platform-Level Interrupt Controller (PLIC)
2 K230 Watchdog Timer
5 UART

Boot options

The k230 machine supports K230 SDK boot through M-mode U-Boot, which then starts OpenSBI/Linux with bootm. It also supports direct Linux boot.

K230 SDK Linux kernels use T-HEAD C9xx private MAEE page table attributes. QEMU does not implement MAEE in the generic RISC-V MMU, so such kernels need to be built with standard RISC-V PTE bits before they can boot under QEMU.

Running

Direct Linux boot

This flow lets QEMU load OpenSBI, Linux, initrd, and DTB directly, without running SDK U-Boot. The Linux Image must be rebuilt with standard RISC-V PTE bits before running under QEMU.

$ SDK=k230_sdk/output/k230_canmv_defconfig
$ qemu-system-riscv64 -machine k230 \
   -kernel "$SDK/images/little-core/Image" \
   -dtb "/tmp/user-k230-qemu.dtb" \
   -initrd "$SDK/images/little-core/rootfs.cpio.gz" \
   -append "console=ttyS0,115200 earlycon=sbi cma=0" \
   -nographic

Direct boot uses the SDK little-core RAM layout for OpenSBI at 0x08000000, Linux at 0x08200000, and the DTB at 0x0a000000. The initrd is placed by QEMU’s generic RISC-V boot helper, and QEMU writes the initrd range and kernel command line into /chosen. The DTB passed with -dtb should be derived from $SDK/images/little-core/k230.dtb and must describe that initrd location as usable memory and disable any devices that are not emulated by this machine.

U-Boot boot

This flow starts SDK U-Boot in M-mode with -bios. Until the SDK storage path is modeled, place OpenSBI, Linux, initrd, and DTB in RAM with loader devices and run bootm manually. The Linux Image must be rebuilt with standard RISC-V PTE bits before running under QEMU.

$ SDK=k230_sdk/output/k230_canmv_defconfig
$ IMAGE=$SDK/images/little-core/Image
$ INITRD=$SDK/images/little-core/rootfs.cpio.gz
$ DTB=$SDK/images/little-core/k230.dtb
$ FWJUMP_UIMAGE=/tmp/k230-fw-jump.uImage
$ INITRD_END=$(printf "0x%x" $((0x0a100000 + $(stat -c %s "$INITRD"))))
$ "$SDK/little/buildroot-ext/host/bin/mkimage" \
   -A riscv -O linux -T kernel -C none \
   -a 0x8000000 -e 0x8000000 -n opensbi \
   -d "$SDK/images/little-core/fw_jump.bin" "$FWJUMP_UIMAGE"
$ qemu-system-riscv64 -machine k230 \
   -bios "$SDK/little/uboot/u-boot" \
   -device loader,file="$FWJUMP_UIMAGE",addr=0xc100000,force-raw=on \
   -device loader,file="$IMAGE",addr=0x8200000,force-raw=on \
   -device loader,file="$INITRD",addr=0xa100000,force-raw=on \
   -device loader,file="$DTB",addr=0xa000000,force-raw=on \
   -nographic

The loader addresses mirror the SDK k230_canmv_defconfig output. Read the U-Boot addresses from the generated environment, and read the Linux RAM base from the generated hw/k230.dts.txt. This replaces the SDK storage and decompression steps.

Press Enter to stop autoboot. At the U-Boot prompt, run these commands:

K230# setenv bootargs console=ttyS0,115200 earlycon=sbi cma=0
K230# fdt addr 0xa000000
K230# fdt resize 8192
K230# fdt set /chosen linux,initrd-start <0x0 0xa100000>
K230# fdt set /chosen linux,initrd-end <0x0 ${INITRD_END}>
K230# fdt set /soc/sdhci0@91580000 status disabled
K230# fdt set /soc/sdhci1@91581000 status disabled
K230# bootm 0xc100000 - 0xa000000

Use setenv so bootm writes the kernel command line into /chosen/bootargs. The fdt commands select the loaded DTB, add space for edits, describe the initrd range in /chosen, and disable SDHCI nodes because this machine does not emulate those controllers yet. Replace ${INITRD_END} with the host-calculated value above when typing the command. cma=0 avoids the SDK kernel reserving too much of the little-core memory window for initramfs boot.

Kendryte K230 virt reference platform (k230)