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

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Message-ID: <87wpji70ui.fsf@purkki.adurom.net>
Date:	Mon, 15 Aug 2016 14:01:09 +0300
From:	Kalle Valo <kvalo@...eaurora.org>
To:	"Pan\, Miaoqing" <miaoqing@....qualcomm.com>
Cc:	Stephan Mueller <smueller@...onox.de>, Ted Tso <tytso@....edu>,
	"Sepehrdad\, Pouyan" <pouyans@....qualcomm.com>,
	"herbert\@gondor.apana.org.au" <herbert@...dor.apana.org.au>,
	"linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-crypto\@vger.kernel.org" <linux-crypto@...r.kernel.org>,
	ath9k-devel <ath9k-devel@....qualcomm.com>,
	"linux-wireless\@vger.kernel.org" <linux-wireless@...r.kernel.org>,
	"ath9k-devel\@lists.ath9k.org" <ath9k-devel@...ts.ath9k.org>,
	"Jason Cooper" <jason@...edaemon.net>
Subject: Re: [PATCH v2] RANDOM: ATH9K RNG delivers zero bits of entropy

"Pan, Miaoqing" <miaoqing@....qualcomm.com> writes:

> The entropy was evaluated by crypto expert, the analysis report show
> the ADC with at least 10bits and up to 22 bits of min-entropy for a 32
> bits value, we conservatively assume the min-entropy is 10 bits out of
> 32 bits, so that's why set entropy quality to 320/1024 = 10/32. Also
> we have explained in the commit message why can't use the HW RNG
> framework.
>
> Otherwise, your patch will cause high CPU load, as continuously read
> ADC data if entropy bits under write_wakeup_threshold.

Please don't top post, it breaks patchwork which is extremely annoying
for me:

https://patchwork.kernel.org/patch/9266265/

https://patchwork.kernel.org/patch/9266617/

-- 
Kalle Valo