Documentation/Platforms/RISCV

Description

RISC-V is an open source instruction set. It is a modular with only a small set of mandatory instructions. Every other module might be implemented by vendors allowing RISC-V to be suitable for small embedded systems up to large supercomputers.

Build Directions

For RV64:

 ./configure --target-list=riscv64-softmmu && make

For RV32:

 ./configure --target-list=riscv32-softmmu && make

Booting Linux

Booting 64-bit Debian

Follow the instructions on the Debian wiki to boot Debian on QEMU: https://wiki.debian.org/RISC-V

Booting 64-bit Fedora

Download the Fedora prebuilt images from: https://dl.fedoraproject.org/pub/alt/risc-v/repo/virt-builder-images/images/ You will want to download Fedora-Minimal-Rawhide-*-fw_payload-uboot-qemu-virt-smode.elf and Fedora-Minimal-Rawhide-*-sda.raw.xz images

Decompress the rootFS:

  unxz Fedora-Minimal-Rawhide-*-sda.raw.xz

Boot linux using RV64GC qemu:

  qemu-system-riscv64 \
   -nographic \
   -machine virt \
   -smp 4 \
   -m 2G \
   -kernel Fedora-Minimal-Rawhide-*-fw_payload-uboot-qemu-virt-smode.elf \
   -bios none \
   -object rng-random,filename=/dev/urandom,id=rng0 \
   -device virtio-rng-device,rng=rng0 \
   -device virtio-blk-device,drive=hd0 \
   -drive file=Fedora-Minimal-Rawhide-20200108.n.0-sda.raw,format=raw,id=hd0 \
   -device virtio-net-device,netdev=usernet \
   -netdev user,id=usernet,hostfwd=tcp::10000-:22

Login: root
Password: riscv

For more details on running Fedora see the Fedora Wiki: https://fedoraproject.org/wiki/Architectures/RISC-V/Installing

Booting 32-bit OpenEmbedded Images

Follow the usual OpenEmbedded build flow using meta-riscv to build for the qemuriscv32 machine.

   MACHINE=qemuriscv32 bitbake core-image-minimal; runqemu qemuriscv32

More details on doing this can be found here: https://github.com/riscv/meta-riscv/#build-image

When using OpenEmbedded it is recommended to use the runqemu script to boot QEMU. It will dynamically handle display options as well as advanced networking.

Booting 64-bit OpenEmbedded Images

Follow the usual OpenEmbedded build flow using meta-riscv to build for the qemuriscv64 machine.

   MACHINE=qemuriscv64 bitbake core-image-minimal; runqemu qemuriscv64

More details on doing this can be found here: https://github.com/riscv/meta-riscv/#build-image

When using OpenEmbedded it is recommended to use the runqemu script to boot QEMU. It will dynamically handle display options as well as advanced networking.

Booting 32-bit Buildroot Images

Clone the Buildroot source code and cd into the directory.

Generate the default config:

 make qemu_riscv32_virt_defconfig

Build the images

 make

Boot the images:

 qemu-system-riscv32 \
   -M virt -nographic \
   -bios output/images/fw_jump.elf \
   -kernel output/images/Image \
   -append "root=/dev/vda ro" \
   -drive file=output/images/rootfs.ext2,format=raw,id=hd0 \
   -device virtio-blk-device,drive=hd0 \
   -netdev user,id=net0 -device virtio-net-device,netdev=net0

Booting 64-bit Buildroot Images

Clone the Buildroot source code and cd into the directory.

Generate the default config:

 make qemu_riscv64_virt_defconfig

Build the images

 make

Boot the images:

 qemu-system-riscv64 \
   -M virt -nographic \
   -bios output/images/fw_jump.elf \
   -kernel output/images/Image \
   -append "root=/dev/vda ro" \
   -drive file=output/images/rootfs.ext2,format=raw,id=hd0 \
   -device virtio-blk-device,drive=hd0 \
   -netdev user,id=net0 -device virtio-net-device,netdev=net0

Microchip PolarFire SoC Icicle Kit

QEMU 5.2.0 supports a new machine: Microchip PolarFire SoC Icicle Kit. The Icicle Kit board integrates a PolarFire SoC, with one SiFive's E51 plus four U54 cores and many on-chip peripherals and an FPGA.

For more details about Microchip PolarFire Soc, please see: https://www.microsemi.com/product-directory/soc-fpgas/5498-polarfire-soc-fpga

The Icicle Kit board information can be found here: https://www.microsemi.com/existing-parts/parts/152514

Boot the images:

 qemu-system-riscv64 -M microchip-icicle-kit -smp 5 \
   -bios path/to/hss.bin -sd path/to/sdcard.img \
   -nic user,model=cadence_gem \
   -nic tap,ifname=tap,model=cadence_gem,script=no \
   -display none -serial stdio \
   -chardev socket,id=serial1,path=serial1.sock,server,wait \
   -serial chardev:serial1

The BIOS image used by this machine is hss.bin, aka Hart Software Services, which can be built from: https://github.com/polarfire-soc/hart-software-services

QEMU does not support eMMC hence the SD configuration shall be used in the HSS and Yocto BSP build. The eMMC configuration is not supported.

Instructions to build HSS:

 $ cp boards/icicle-kit-es/def_config.sdcard .config
 $ make BOARD=icicle-kit-es

The following commit of HSS was tested:

 commit 078ce16d8cb3a89e4c3e93916621b816dbdaa274
 Merge: 76b34dd 2cd45c9
 Author: Cyril-Jean <cyril.jean@microchip.com>
 Date:   Fri Oct 9 17:07:12 2020 +0100
 
   Merge pull request #7 from avpatel/custom_boot_flow_v1
 
   Custom boot flow for PolarFire boards

For Yocto build, "MACHINE=icicle-kit-es-sd" should be specified, otherwise when booting Linux kernel the rootfs cannot be mounted. The generated image is something like: mpfs-dev-cli-icicle-kit-es-sd.rootfs.wic. Resize the file with 'qemu-image' to a power of 2 before passing to QEMU '-sd' command line.

The following commands download the official SD card image released by Microchip and prepare it for QEMU usage:

 $ wget ftp://ftpsoc.microsemi.com/outgoing/core-image-minimal-dev-icicle-kit-es-sd-20201009141623.rootfs.wic.gz
 $ gunzip core-image-minimal-dev-icicle-kit-es-sd-20201009141623.rootfs.wic.gz
 $ qemu-img resize core-image-minimal-dev-icicle-kit-es-sd-20201009141623.rootfs.wic 4G

The memory is set to 1537 MiB by default which is the minimum required high memory size by HSS. A sanity check on ram size is performed in the machine init routine to prompt user to increase the RAM size to > 1537 MiB when less than 1537 MiB ram is detected.

HSS output is on the first serial port (stdio) and U-Boot/Linux outputs on the 2nd serial port. OpenSBI outputs on a random serial port due to the lottery mechanism used during the multi-core boot.

Attaching GDB

To attach GDB to a QEMU RISC-V instance with only a single cluster (every machine except the sifive_u) run these commands from GDB:

 target extended-remote :1234
 info threads

To attach GDB to a QEMU RISC-V instance with multiple clusters (the sifive_u) run these commands from GDB:

 target extended-remote :1234
 add-inferior
 inferior 2
 attach 2
 set schedule-multiple
 info threads

The above commands assume the default GDB port exposed from QEMU of 1234. This will happen when you run QEMU with the '-s' command line argument.

If you would like QEMU to not run the guest until you have connected GDB, you can specify the '-S' command line argument as well.

Links

Contacts

Maintainers: