This gets this package to build for `x86_64`, but does not include any cache clearing for `aarch64-freebsd`. Which will probably build, but not work. As far as I can tell membarriers are still in the process of being added. See: https://reviews.freebsd.org/D32360 Since FreeBSD is mirroring the Linux membarrier syscall we may be able to reuse the same implementation for both Linux and FreeBSD for AArch64.