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Date:   Mon, 7 Nov 2022 08:37:52 +0100
From:   Dominik Brodowski <linux@dominikbrodowski.net>
To:     "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc:     herbert@gondor.apana.org.au, linux-crypto@vger.kernel.org
Subject: Re: [PATCH v2] hw_random: use add_hwgenerator_randomness() for early
 entropy
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Hi Jason,

Am Sun, Nov 06, 2022 at 03:50:51PM +0100 schrieb Jason A. Donenfeld:
> On Sun, Nov 06, 2022 at 08:02:56AM +0100, Dominik Brodowski wrote:
> > Am Sun, Nov 06, 2022 at 02:50:42AM +0100 schrieb Jason A. Donenfeld:
> > > Rather than calling add_device_randomness(), the add_early_randomness()
> > > function should use add_hwgenerator_randomness(), so that the early
> > > entropy can be potentially credited, which allows for the RNG to
> > > initialize earlier without having to wait for the kthread to come up.
> > 
> > We're already at device_initcall() level here, so that shouldn't be much of
> > an additional delay.
> 
> Either the delay is not relevant, in which case we should entirely
> remove `add_early_randomness()`,

There's another subtlety going on here: add_device_randomness() is called
for *all* hw_random devices upon their registration, while the hwrng thread
currently only works with the hw_random device with the best quality
available.

Thanks,
	Dominik