Try using ncr.defs those are for a sysv4 386 machine. mp386.defs are for a sysV3 386, and that is very different. save and build of the system work fine under ncr.defs, however I have NOT done the sfasl stuff to allow loading the native elf .o files. You may be able to make gcc put out coff files, and then load those in using the set up for mp386