alt Hacker NewsI have a couple questions:
Looks like they tried 16-bit numbers. Does the odd behavior happen also on 32 and 64 (might take a long time to check - I'd start scratching my head after a couple hundred years of no zeroes) ones? Is the zero masking as some other fixed number, increasing its output count? Is RDRAND implemented as multiple reads of an internal state so that a larger random number takes longer?
That first question is answered in the thread:
> Yes, when using either 32-bit or 64-bit number, the lowest portion can output a zero, as I suggested on the attached example file as a modification to fix the problem. But a true zero (fitting the requested size), on AMD, never happens.
Another person (on page 2) confirms those results on an older AMD processor (but failed to reproduce on a very new one, 9950X3D).