Sorry, I missed this comment when I brought the issue up below. (I was on my phone, which is sort of an excuse...) With a thread-local RNG (and a thread-local

Sorry, I missed this comment when I brought the issue up below. (I was on my phone, which is sort of an excuse...) With a thread-local RNG (and a thread-local page which gets zeroed on fork) it sounds like you're probably best off extracting data from the RNG and then checking the flag to see if you need to go back and try again. The only cost of doing it this way is a very marginal extra cost whenever you need to regenerate entropy -- but you can think of that as just being a slight increase in the cost of the fork. The only other question which comes to mind is whether you need to worry about breakage on systems which have weaker-than-x86 cache coherency. I'm 99% certain that you're fine, but I'd prefer to be 100% certain. I assume you'd like to see this functionality added to other platforms as well?