https://bugs.libre-soc.org/show_bug.cgi?id=419#c14 the ov and o ok flags must be much more specifically constrained. also xer_so output is a Data type so needs copying properly.
commit dc3a864af70e9b227771219d6b5a53296e10b78c (HEAD -> master) Author: Luke Kenneth Casson Leighton <lkcl@lkcl.net> Date: Sun Aug 30 10:51:30 2020 +0100 set mul post_stage o.ok only when needed, and fix xer_so pass-through