Re: [PATCH] hw_random: treat default_quality as a maximum and default to 1024

["Jason A. Donenfeld" <Jason@zx2c4.com>]

Hi Harald,

On Mon, Nov 07, 2022 at 10:24:42AM +0100, Harald Freudenberger wrote:
> Well, I am not sure if this is the right way to go. So by default a
> hw rng which does not implement the registration correctly is
> rewarded with the implicit assumption that it produces 100% of
> entropy.
> I see your point - a grep through the kernel code gives the impression
> that a whole bunch of registrations is done with an empty quality
> field. What about assuming a default quality of 50% if the field
> is not filled ?

The vast majority of hardware RNGs do *not* work this way. The
reasonable assumption is to assume that a hardware RNG provides fully
random bits, unless the documentation leads the driver author to specify
something less.

Really, just quit with all the nutty mailing list stuff here. Next: "how
about 74.4% because that matches the vibrations of cedar trees"... If
you want this to be different on a particular kernel, you can set your
exact value as a command line. This patch here is simply about a
sensible default.

Jason