Re: [PATCH v2] RANDOM: ATH9K RNG delivers zero bits of entropy

[Jason Cooper <jason@lakedaemon.net>]

Hi Stephan,

On Mon, Aug 08, 2016 at 05:29:30PM +0000, Jason Cooper wrote:
> On Mon, Aug 08, 2016 at 08:41:36AM +0200, Stephan Mueller wrote:
...
> > If you think that this patch is a challenge because your driver starts to 
> > spin, please help and offer another solution.
> 
> Well, I don't buy the reasoning listed above for not using the hwrng
> framework.  Interrupt timings were never designed to be a source of entropy
> either.  We need to grab it where ever we can find it, especially on
> embedded systems.  Documentation/hw_random.txt even says:
> 
> """
> This data is NOT CHECKED by any fitness tests, and could potentially be
> bogus (if the hardware is faulty or has been tampered with).
> """
> 
> I really don't think there's a problem with adding these sorts of
> sources under char/hw_random/.  I think the only thing we would be
> concerned about, other than the already addressed entropy estimation,
> would be constraining the data rate.

Further research yields char/hw_random/timeriomem-rng.c

It could use an update to ->read() vice data_{present,read}(), but it's
functionally exactly what the ath9k rng is doing. :)

thx,

Jason.