• riscv
• bhyve

The page is dedicated to riscv "H"-extension[1].

The RISC-V Hypervisor specification virtualizes supervisor-level architecture to efficiently host guest operating systems atop a type-1 or type-2 hypervisor. Virtual machine implementations require the RISC-V Hypervisor specification. The Hypervisor specification will help drive RISC-V adoption in cloud and embedded applications where virtualization is critical, such as in data centers, automotive applications, and industrial control applications.

1. https://github.com/riscv/riscv-isa-manual/blob/main/src/hypervisor.adoc

2. https://five-embeddev.com/riscv-priv-isa-manual/Priv-v1.12/hypervisor.html

Code:

• userspace part

  kernel part

Project Status

Hardware

At the moment, no real hardware with H-extension implemented available.

Instructions

Build FreeBSD (VM host)

Apply VMM kernel & userspace patches to your freebsd repository and build it as usual.

Prepare OpenSBI (host)

git clone https://github.com/riscv/opensbi.git
cd opensbi
gmake -j24 CROSS_COMPILE=riscv64-none-elf- PLATFORM=generic

Alternatively,

sudo pkg install opensbi

Fetch guest root fs

fetch https://download.freebsd.org/snapshots/VM-IMAGES/15.0-CURRENT/riscv64/Latest/FreeBSD-15.0-CURRENT-riscv-riscv64-ufs.qcow2.xz
unxz FreeBSD-15.0-CURRENT-riscv-riscv64-ufs.qcow2.xz

QEMU

git clone https://github.com/qemu/qemu
cd qemu
mkdir build && cd build
../configure --target-list=riscv64-softmmu
gmake -j `sysctl -n hw.ncpu`

Run QEMU

Add more storage devices if needed (e.g. VM-host rootfs). In my case I use mdroot, so the only drive in the command line below is guest-rootfs disk.

./qemu-system-riscv64 -nographic \
        -machine virt \
        -cpu 'rv64,h=true' \
        -smp 8 \
        -device virtio-scsi-pci,id=scsi \
        -drive file=FreeBSD-15.0-CURRENT-riscv-riscv64-ufs.qcow2,id=disk,format=qcow2,if=none,cache=writeback -device scsi-hd,drive=disk \
        -m 16G \
        -device virtio-rng-pci \
        -bios /usr/local/share/opensbi/lp64/generic/firmware/fw_jump.elf \
        -kernel /usr/obj/usr/home/br/dev/freebsd/riscv.riscv64/sys/GENERIC/kernel.bin

Bhyve

This has to be run on freebsd that is booted up in QEMU. Ensure you have u-boot.bin on your qemu rootfs.

bhyve -c 8 -m 256 -o bootrom=/usr/local/share/u-boot/u-boot-bhyve-riscv/u-boot.bin -o console=stdio -s 4,virtio-blk,/dev/da0 test

Linux Guest

Step 1. Build linux

git clone https://github.com/torvalds/linux
cd linux
make ARCH=riscv defconfig
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu-

Result file: ./arch/riscv/boot/Image

Step 2. Build busybox

git clone https://git.busybox.net/busybox 
cd busybox
make ARCH=riscv defconfig
make menuconfig

1. In the "Settings" menu, enable "Build static binary (no shared libs)".
2. In the "Networking Utilities" menu, disable tc.

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

Step 3. Build initrd

cd busybox
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- CONFIG_PREFIX=../initramfs install
cd ../
mkdir -p initramfs/{bin,sbin,etc,proc,sys,usr/{bin,sbin},dev}
sudo mknod -m 622 initramfs/dev/console c 5 1
sudo mknod -m 666 initramfs/dev/null c 1 3

bash

cat << 'EOF' > initramfs/init
#!/bin/sh
mount -t proc none /proc
mount -t sysfs none /sys
echo "Welcome to RISC-V Initrd"
exec /bin/sh
EOF

chmod +x initramfs/init

cd initramfs
find . | cpio -o -H newc | gzip > ../initrd.img

Step 4. Make ramdisk

mkimage -A riscv -T ramdisk -C gzip -n "Ramdisk" -d initrd.img ramdisk.img

Step 5. Create file system.

1. Create a linux.raw disk image with a FAT32 partition.
2. Copy linux Image and ramdisk to it.

Step 6. Prepare u-boot

pkg install u-boot-bhyve-riscv

Result file: /usr/local/share/u-boot/u-boot-bhyve-riscv/u-boot.bin

Step 7. Run Bhyve

bhyve -c 1 -m 4096 -o bootrom=/path/to/u-boot.bin -o console=stdio -s 4,virtio-blk,/path/to/linux.raw linux

Step 8. Run Linux from U-Boot

setenv bootargs 'console=ttyS0,115200n8 rw root=/dev/ram0 earlycon=uart8250,mmio32,0x10000'
fatload virtio 0 0x100000000 Image
fatload virtio 0 0x110000000 ramdisk.img
booti 0x100000000 0x110000000 $fdt_addr