[enjolras]

look at the code. AT_RANDOM is. used when it's avaible in the fallback function. For some reason, the devs don't seem to trust it much, according to the comment.

[edwintorok]

Is it guaranteed to at least be different for different processes? They could use that in addition to the PID test to know when to reseed.

[wahern]

No. It's only filled on execve, not fork.