The current implementation of mqueuefs in the Linuxulator is a skeleton that is enabled only for i386 when P1003_1B_MQUEUE is defined. This is wrong. Either this must be disabled or fixed. This is an attempt of a fix for amd64 which works so far with some limitations. I need some comments on whether this is an exercise in futility (who really uses mqueue?) or worth trying: https://github.com/freebsd/freebsd-src/pull/1248 PR:1248