[bitwize]

But it does emulate the 16-bit x86 instructions from really old-school Windows code.

[rep_lodsb]

No it doesn't. 16-bit protected mode code will run natively even on 64-bit kernels - and there is a system call that can create the segment descriptors needed for that: https://man7.org/linux/man-pages/man2/modify_ldt.2.html