在QEMU上运行RISCV平台Linux

QEMU支持如下RISC-V平台：

• Spike是官方的RISC-V模拟平台。
• SiFive的E和U系列。
• Virt是通用的虚拟化RISC-V平台，支持VirtIO设备。

$ qemu-system-riscv64 -M ?
Supported machines are:
none                 empty machine
sifive_e             RISC-V Board compatible with SiFive E SDK
sifive_u             RISC-V Board compatible with SiFive U SDK
spike                RISC-V Spike Board (default)
spike_v1.10          RISC-V Spike Board (Privileged ISA v1.10)
spike_v1.9.1         RISC-V Spike Board (Privileged ISA v1.9.1)
virt                 RISC-V VirtIO board

QEMU RISC-V模拟了如下硬件特性:

• HTIF Console (Host Target Interface) for Spike emulation
• SiFive CLINT (Core Local Interruptor) for Timer interrupts and IPIs
• SiFive PLIC (Platform Level Interrupt Controller) for multi-core interrupts
• SiFive Test (Test Finisher) for exiting simulations in tests
• SiFive UART for console on the SiFive U series and E series devices
• SiFive PRCI, AON, PWM, QSPI mocks for SiFive E series devices
• VirtIO MMIO for network and block device support
• Generic 16550A UART emulation on the ‘virt’ board
• SMP and MTTCG support for multi-core emulation

编译Linux内核：

make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- defconfig
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- menuconfig
make ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- Image -j8

获取rootfs：busybox是一个用busybox制作的微型rootfs。

https://github.com/michaeljclark/busybear-linux/releases

安装opensbi固件：

sudo apt install opensbi

在qemu中用opensbi固件启动Linux内核：

qemu-system-riscv64 -nographic -machine virt -serial mon:stdio \
-bios /usr/lib/riscv64-linux-gnu/opensbi/qemu/virt/fw_jump.elf \
-kernel arch/riscv/boot/Image -append "root=/dev/vda ro console=ttyS0" \
-drive file=../images/busybear.img,format=raw,id=hd0 \
-device virtio-blk-device,drive=hd0