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List: netbsd-tech-kern
Subject: Re: RND_TYPE_RNG question concerning rate of random bits production
From: Frank Zerangue <frank.zerangue () gmail ! com>
Date: 2014-01-27 19:26:52
Message-ID: 835895FE-57C9-40A7-B310-5BD83E9B2550 () gmail ! com
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Taylor. That is much appreciated. I was on the 6.1.2 release.
Thanks --
On Jan 27, 2014, at 1:17 PM, Taylor R Campbell wrote:
> Date: Mon, 27 Jan 2014 13:05:58 -0600
> From: Frank Zerangue <frank.zerangue@gmail.com>
>
> 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.
>
> Perhaps you're not looking at the code in HEAD. See, e.g.,
>
> http://nxr.netbsd.org/xref/src/sys/arch/arm/broadcom/bcm2835_rng.c#128
>
> which sets up a callback so that when the system thinks it needs some
> more entropy, it will call bcmrng_get_cb, which schedules a softintr
> to actually read data from the hardware and feed it to the system
> entropy pool.
>
> This API is not yet stable -- at least, some months ago, Thor and I
> discussed changing it to render the softintr indirection and locking
> dance unnecessary -- but it will work for now.
--
Frank Zerangue
frank.zerangue@gmail.com
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