support for having both 32 and 64 bit RISC-V CPUs in one QEMU machine

[Igor Lesik]

Hi,

I have a situation when I need to use third-party 32-bit RISC-V CPU when rest 
is all 64-bit RISC-V CPUs. I have seen that some steps were already made in the 
direction to enable such configuration 
(https://riscv.org/blog/2023/01/run-32-bit-applications-on-64-bit-linux-kernel-liu-zhiwei-guo-ren-t-head-division-of-alibaba-cloud/),
 I am wondering if someone can shed more light on it.

Thanks,
Igor