Re: Lightweight support for instruction RNGs

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

   Date: Sat, 19 Dec 2015 19:37:22 -0500
   From: Thor Lancelot Simon <tls%panix.com@localhost>

   I was playing with code for a RDRAND/RDSEED entropy source and it
   just felt like -- much like opencrypto is poorly suited for crypto
   via unprivileged CPU instructions -- our rndsource interface is
   a little too heavy for CPU RNGs implemented as instructions.

Why is it a little too heavy?  How does the cpu_rng abstraction
improve it?

I'm very leery of adding more mechanism to an already unbelievably
complicated entropy pool system, and particularly of a special
mechanism for RDRAND/RDSEED.

I think we'd be better off simplifying what we have than adding new
bells and whistles.