> For those purposes, qemu-user works quite well: we are even considering using it to build the entire riscv64 architecture in the 3.15 release.
We‘ve been doing that in Debian on m68k and sh4 for quite a while now and it helped finding quite a lot of bugs, both in the target-specific emulation code and in the qemu-user code.
There is still one nasty bug in conjunction with glibc if anyone wants to help: