解决qemu-system-riscv64运行RISC-V根文件系统ROM区域重叠错误

我在Ubuntu 22.04虚拟机上尝试用qemu-system-riscv64运行RISC-V Linux根文件系统，执行以下启动命令时出现地址重叠错误：

sudo qemu-system-riscv64 -nographic -machine virt 
  -kernel bbl -append "root=/dev/vda ro console=ttyS0" 
  -drive file=riscv64-rootfs.bin,format=raw,id=hd0 
  -device virtio-blk-device,drive=hd0 
  -netdev type=tap,script=scripts/ifup.sh,downscript=scripts/ifdown.sh,id=net0 
  -device virtio-net-device,netdev=net0

错误信息如下：

qemu-system-riscv64: Some ROM regions are overlapping
These ROM regions might have been loaded by direct user request or by default.
They could be BIOS/firmware images, a guest kernel, initrd or some other file loaded into guest memory.
Check whether you intended to load all this guest code, and whether it has been built to load to the correct addresses.
The following two regions overlap (in the memory address space):
/usr/share/qemu/opensbi-riscv64-generic-fw_dynamic.bin (addresses 0x0000000080000000 - 0x0000000080012630)
build/riscv-pk/bbl ELF program header segment 1 (addresses 0x0000000080000000 - 0x000000008000690d)
make: *** [Makefile:13: run] Error 1

请问该问题是否与嵌套虚拟化或Ubuntu版本有关？恳请提供解决建议。

解决建议 #

这个错误和嵌套虚拟化、Ubuntu版本无关，核心原因是QEMU默认加载的OpenSBI固件和你指定的bbl（RISC-V Proxy Kernel）都试图占用0x80000000起始的内存地址空间，导致冲突。bbl本身已经集成了OpenSBI的功能，不需要QEMU再额外加载一份固件，以下是两种可行的解决方法：

• 方法1：禁用QEMU默认OpenSBI固件
  在启动命令中添加-bios none参数，让QEMU只加载你指定的bbl。修改后的命令：

  sudo qemu-system-riscv64 -nographic -machine virt -bios none \
    -kernel bbl -append "root=/dev/vda ro console=ttyS0" \
    -drive file=riscv64-rootfs.bin,format=raw,id=hd0 \
    -device virtio-blk-device,drive=hd0 \
    -netdev type=tap,script=scripts/ifup.sh,downscript=scripts/ifdown.sh,id=net0 \
    -device virtio-net-device,netdev=net0
  

• 方法2：改用OpenSBI直接引导Linux内核
  如果你的根文件系统构建时生成了单独的Linux内核镜像（如vmlinux或Image），可以直接用QEMU默认的OpenSBI引导内核，不再依赖bbl：

  sudo qemu-system-riscv64 -nographic -machine virt \
    -kernel vmlinux -append "root=/dev/vda ro console=ttyS0" \
    -drive file=riscv64-rootfs.bin,format=raw,id=hd0 \
    -device virtio-blk-device,drive=hd0 \
    -netdev type=tap,script=scripts/ifup.sh,downscript=scripts/ifdown.sh,id=net0 \
    -device virtio-net-device,netdev=net0
  

两种方法任选其一即可解决地址重叠问题。

内容的提问来源于stack exchange，提问作者izzy