```
This is an attempt at clean-room implementation of the Linux'
membarrier(2) syscall. For documentation, you would need to read
both membarrier(2) Linux man page, the comments in Linux
kernel/sched/membarrier.c implementation and possibly look at
actual uses.
I was not able to decode the meaning of
MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ. I doubt that it might be
explained in portable terms.
```