Re: Question about riscv-qemu trace

[Frank Chang]

Zahra Azad <zazad@bu.edu> 於 2021年9月12日 週日 下午12:33寫道：

Hi all,

I want to use riscv-qemu to get a trace of the guest executed instructions of a vectorized program. I'm using the following command:

qemu-riscv64 -cpu rv64,x-v=true,x-k=true,vlen=256,elen=64,vext_spec=v1.0 -D logfile.log -d in_asm,cpu,fpu program

Although the program is executed correctly without throwing any error, in the trace log all the vector instructions are shown as illegal instructions. Any ideas what is going wrong?

I built riscv toolchain and llvm from the main branch (following sifive instructions), and riscv qemu is built from https://github.com/sifive/qemu/tree/v5.2.0-rvv-rvb-zfh.

Thank you!

Hi Zahra,

We are missing RVV related instructions disassembler in QEMU.

The illegal instruction messages for vector instructions in the trace log are just false alarms for now.

We need to update disas/riscv.c to decode RVV instructions properly.

Regards,

Frank Chang