From: Jean-Francois Moine <moinejf@free.fr>
Subject: Re: [PATCH] nvmem: sunxi-sid: SID content is not a valid source of
 randomness
Date: Tue, 25 Oct 2016 09:06:34 +0200
Message-ID: <20161025090634.3dae9ad52ae8382dde6af4c8@free.fr>
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        <20161024201020.h6akyqad2o42xkhq@lukather>
        <20161025053855.GA901@Red>
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Cc: Maxime Ripard <maxime.ripard@free-electrons.com>, wens@csie.org,
        srinivas.kandagatla@linaro.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org
To: LABBE Corentin <clabbe.montjoie@gmail.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20161025053855.GA901@Red>
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On Tue, 25 Oct 2016 07:38:55 +0200
LABBE Corentin <clabbe.montjoie@gmail.com> wrote:

> > On Sat, Oct 22, 2016 at 03:53:28PM +0200, Corentin Labbe wrote:
> > > Since SID's content is constant over reboot,
> > 
> > That's not true, at least not across all the Allwinner SoCs, and
> > especially not on the A10 and A20 that this driver supports.
> > 
> 
> On my cubieboard2 (A20)
> hexdump -C /sys/devices/platform/soc\@01c00000/1c23800.eeprom/sunxi-sid0/nvmem 
> 00000000  16 51 66 83 80 48 50 72  56 54 48 48 03 c2 75 72  |.Qf..HPrVTHH..ur|
> 00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> *
> 00000100  16 51 66 83 80 48 50 72  56 54 48 48 03 c2 75 72  |.Qf..HPrVTHH..ur|
> 00000110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> *
> 00000200
> cubiedev ~ # reboot
> cubiedev ~ # hexdump -C /sys/devices/platform/soc\@01c00000/1c23800.eeprom/sunxi-sid0/nvmem 
> 00000000  16 51 66 83 80 48 50 72  56 54 48 48 03 c2 75 72  |.Qf..HPrVTHH..ur|
> 00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> *
> 00000100  16 51 66 83 80 48 50 72  56 54 48 48 03 c2 75 72  |.Qf..HPrVTHH..ur|
> 00000110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
> *
> 00000200
> 
> So clearly for me its constant.

Even after power off/power on?

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