[goalieca]

The RDRAND instruction usage is configurable https://github.com/torvalds/linux/blob/master/Documentation/...

edit: https://github.com/torvalds/linux/blob/55cb5f43689d7a9ea5bf3...

[oittaa]

If I remember correctly, the TLDR is that RDRAND output is mixed with other "standard" entropy sources and basically making getrandom() non-blocking immediately.