what branch or tag is suitable for riscv-qemu about riscv-linux

[palmer-dabbelt]

I just merged QEMU support into freedom-u-sdk's master branch. It's still a bit rough around the edges, but on a clean build I can "make qemu" and get into a shell with a DHCP lease.

[michaeljclark]

You can use the riscv-qemu branch in freedom-u-sdk. If you do, make sure to unset RISCV environment variable if you have it set (as it needs a specific version of riscv-gnu-toolchain), then run make qemu and the SDK will build qemu, a buildroot rootfs and linux-kernel, then start it up:

unset RISCV
git clone --recursive https://github.com/sifive/freedom-u-sdk.git
cd freedom-u-sdk
make qemu

If you want SMP support, you'll need a more recent version of QEMU. The default riscv-qemu riscv-next branch has relatively solid SMP support:

• https://github.com/riscv/riscv-qemu/tree/riscv-next
• sifive/freedom-u-sdk#35

To build an SMP linux-kernel, run menuconfig, enable "Platform Type" -> "Symmetric Multi-Processing"

make ARCH=riscv menuconfig

To enable smp in QEMU, add -smp cpus=4 to the command line.

I've tested SMP kernels in latest qemu using the riscv-linux-4.14 and riscv-linux-4.15 branches.

You can also take a look at the QEMU wiki. I'll add freedom-u-sdk instructions to the QEMU wiki, no i've figured out how to get it building (you must unset RISCV environment variable).

• https://github.com/riscv/riscv-qemu/wiki