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QEMU RISC-V Virt Machine Platform

The QEMU RISC-V Virt Machine is a virtual platform created for RISC-V software development and testing. It is also referred to as QEMU RISC-V VirtIO machine because it uses VirtIO devices for network, storage, and other types of IO.

To build the platform-specific library and firmware images, provide the PLATFORM=generic parameter to the top level make command.

Platform Options

The QEMU RISC-V Virt Machine platform does not have any platform-specific options.

Execution on QEMU RISC-V 64-bit

No Payload Case

Build:

make PLATFORM=generic

Run:

qemu-system-riscv64 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_payload.bin

U-Boot Payload

Note: the command line examples here assume that U-Boot was compiled using the qemu-riscv64_smode_defconfig configuration.

Build:

make PLATFORM=generic FW_PAYLOAD_PATH=<uboot_build_directory>/u-boot.bin

Run:

qemu-system-riscv64 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_payload.elf

or

qemu-system-riscv64 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_jump.bin \
	-kernel <uboot_build_directory>/u-boot.bin

Linux Kernel Payload

Note: We assume that the Linux kernel is compiled using arch/riscv/configs/defconfig. The kernel must be a flattened image (a file called Image) rather than an ELF (vmlinux).

Example of building a Linux kernel:

make ARCH=riscv CROSS_COMPILE=riscv64-linux- defconfig
make ARCH=riscv CROSS_COMPILE=riscv64-linux- Image

Build:

make PLATFORM=generic FW_PAYLOAD_PATH=<linux_build_directory>/arch/riscv/boot/Image

Run:

qemu-system-riscv64 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_payload.elf \
	-drive file=<path_to_linux_rootfs>,format=raw,id=hd0 \
	-device virtio-blk-device,drive=hd0 \
	-append "root=/dev/vda rw console=ttyS0"

or

qemu-system-riscv64 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_jump.bin \
	-kernel <linux_build_directory>/arch/riscv/boot/Image \
	-drive file=<path_to_linux_rootfs>,format=raw,id=hd0 \
	-device virtio-blk-device,drive=hd0 \
	-append "root=/dev/vda rw console=ttyS0"

Execution on QEMU RISC-V 32-bit

No Payload Case

Build:

make PLATFORM=generic PLATFORM_RISCV_XLEN=32

Run:

qemu-system-riscv32 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_payload.bin

U-Boot Payload

Note: the command line examples here assume that U-Boot was compiled using the qemu-riscv32_smode_defconfig configuration.

Build:

make PLATFORM=generic PLATFORM_RISCV_XLEN=32 FW_PAYLOAD_PATH=<uboot_build_directory>/u-boot.bin

Run:

qemu-system-riscv32 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_payload.elf

or

qemu-system-riscv32 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_jump.bin \
	-kernel <uboot_build_directory>/u-boot.bin

Linux Kernel Payload

Note: We assume that the Linux kernel is compiled using arch/riscv/configs/rv32_defconfig.

Build:

make PLATFORM=generic PLATFORM_RISCV_XLEN=32 FW_PAYLOAD_PATH=<linux_build_directory>/arch/riscv/boot/Image

Run:

qemu-system-riscv32 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_payload.elf \
	-drive file=<path_to_linux_rootfs>,format=raw,id=hd0 \
	-device virtio-blk-device,drive=hd0 \
	-append "root=/dev/vda rw console=ttyS0"

or

qemu-system-riscv32 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_jump.bin \
	-kernel <linux_build_directory>/arch/riscv/boot/Image \
	-drive file=<path_to_linux_rootfs>,format=raw,id=hd0 \
	-device virtio-blk-device,drive=hd0 \
	-append "root=/dev/vda rw console=ttyS0"

Debugging with GDB

In a first console start OpenSBI with QEMU:

qemu-system-riscv64 -M virt -m 256M -nographic \
	-bios build/platform/generic/firmware/fw_payload.bin \
	-gdb tcp::1234 \
	-S

Parameter -gdb tcp::1234 specifies 1234 as the debug port. Parameter -S lets QEMU wait at the first instruction.

In a second console start GDB:

gdb build/platform/generic/firmware/fw_payload.elf \
	-ex 'target remote localhost:1234'