linux-kernel - Re: [PATCH] /dev/random: Insufficient of entropy on many architectures

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Message-ID: <20130913000011.GJ3809@logfs.org>
Date:	Thu, 12 Sep 2013 20:00:11 -0400
From:	Jörn Engel <joern@...fs.org>
To:	Theodore Ts'o <tytso@....edu>
Cc:	John Stultz <john.stultz@...aro.org>,
	Stephan Mueller <smueller@...onox.de>,
	LKML <linux-kernel@...r.kernel.org>, dave.taht@...ferbloat.net,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] /dev/random: Insufficient of entropy on many
 architectures

On Thu, 12 September 2013 19:35:36 -0400, Jörn Engel wrote:
> 
> I think the existing code is doing just fine for low interrupt loads.
> It makes sense to spend a bit more work to squeeze the last bit of
> randomness out.  But when you get lots of interrupts, you can be
> sloppy and just xor things into the pool.

Btw, if we make collection cheap enough, we can start collecting
entropy from the scheduler.  Computers are fairly deterministic, but
not that much.  The exact time when calling schedule(), the kernel
stack pointer and the userspace stack pointer all contain a bit of
entropy.  Particularly on machines that lack input and disk
randomness I would expect some benefits from this.

Jörn

--
Audacity augments courage; hesitation, fear.
-- Publilius Syrus
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