Re: RND_TYPE_RNG question concerning rate of random bits production

[Frank Zerangue <frank.zerangue%gmail.com@localhost>]

I looked at hifn, amdpm, and bcm28335 RNG drivers and they all seem to do the 
same. They setup a callout to periodically call there RNG reader to prime the 
random pool with more bits; but I don't see how the polling is based on entropy 
needed. Could you clarify for me what I have missed in regard to your 
suggestion below.

Thanks.

On Jan 15, 2014, at 7:28 PM, Thor Lancelot Simon wrote:

> On Wed, Jan 15, 2014 at 05:26:34PM -0600, Frank Zerangue wrote:
>> I am writing a driver for an arm random number generator accelerator to 
>> provide a source of random bits to rnd_pool.
>> 
>> How does one know at what rate to supply random bits to the pool using 
>> rnd_add_data()? Assume for a moment that more bits/sec can be generated than 
>> are needed, what criteria should be used to decide the rate to provide bits 
>> to the pool? Is there any feedback mechanism that can be used to govern the 
>> flow?
> 
> You can arrange to be polled for entropy when it's needed.  Have a look
> at the hifn, amdpm, or bcm2835 RNG drivers.
> 
> Thor
> 

--
Frank Zerangue
frank.zerangue%gmail.com@localhost