RDRAND on AMD Ryzen 9 5900X is flakey

Re:RDRAND on AMD Ryzen 9 5900X is flakey by holtalanm on Monday January 11, 2021 @05:16PM (#25738225)

I read through the comments on the issue -- correct me if I'm wrong, but with the program they were running (generating 2000 random numbers) isn't there a 5% chance of generating duplicates, even with RDRAND working as intended?

If that is case, maybe RDRAND shouldn't be used for uniqueness.

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Re:RDRAND on AMD Ryzen 9 5900X is flakey by dragontamer on Monday January 11, 2021 @05:17PM (#25738240)

RDRAND can output a 64-bit number.

The intrinsic used is the 32-bit version of RDRAND, which is... suboptimal... for a test like this. As you've noted.

Even then, RDRAND has no entropy guarantees (again: see my top comment about RDSEED vs RDRAND).

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