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From: Niek Linnenbank <nieklinnenbank@gmail.com>
To: "Philippe Mathieu-Daudé" <philmd@redhat.com>
Cc: Beniamino Galvani <b.galvani@gmail.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	qemu-arm <qemu-arm@nongnu.org>,
	QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [PATCH 08/10] arm: allwinner-h3: add Security Identifier device
Date: Fri, 6 Dec 2019 21:20:33 +0100
Message-ID: <CAPan3Wq_fFcHb1TR5bP0O4T8mRo73Fi5Fe-8VNw93Cv6jwLg=g@mail.gmail.com> (raw)
In-Reply-To: <41ab9f5a-3318-b412-44e8-f8571a64da64@redhat.com>


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Hey Peter, Philippe,

On Fri, Dec 6, 2019 at 5:35 PM Philippe Mathieu-Daudé <philmd@redhat.com>
wrote:

> On 12/6/19 3:27 PM, Peter Maydell wrote:
> > On Mon, 2 Dec 2019 at 21:10, Niek Linnenbank <nieklinnenbank@gmail.com>
> wrote:
> >>
> >> The Security Identifier device in Allwinner H3 System on Chip
> >> gives applications a per-board unique identifier. This commit
> >> adds support for the Allwinner H3 Security Identifier using
> >> randomized data as input.
> >
> > If this is a fixed value in hardware, I'm not sure that
> > having the QEMU model pick a random value is the best
> > choice. If we just set it to a fixed value in QEMU, is
> > that going to cause problems?
> >
> > (Generally it's nice for QEMU to be deterministic, so it
> > behaves the same way every time you run it. Also if it's
> > always the same we don't need to bother migrating the
> > ID value.)
>
> Agreed. Since the identifier is 128-bit, I'd use DEFINE_PROP_UUID() or,
> to be even safer, DEFINE_PROP_UUID_NODEFAULT().
> See how the ipmi-bmc-sim device checks its guid field and fails if unset.
>

Thank you both for clarifying this. OK, I'll update this patch such that
the identifier is fixed,
using the functions Philippe suggested.

The reason I originally chose to make it randomized is that U-Boot mainline
reads out the
SID data in order to create a MAC address for the ethernet device. So when
a user runs multiple
QEMU machines inside a virtualized network, they will get the same MACs if
the SID isnt unique.
However this problem can also be solved very easy with U-Boot itself by
just overriding the ethaddr environment variable.

For your interest, in the U-Boot source you can see this behaviour in the
file
arch/arm/mach-sunxi/cpu_info.c:139 in sunxi_get_sid(), sun8i_efuse_read()
where it reads the SID
and in board/sunxi/board.c:782 in setup_environment() where it uses the SID
to create the MAC address.

Regards,
Niek

-- 
Niek Linnenbank

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  reply index

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-02 21:09 [PATCH 00/10] Add Allwinner H3 SoC and Orange Pi PC Machine Niek Linnenbank
2019-12-02 21:09 ` [PATCH 01/10] hw: arm: add Allwinner H3 System-on-Chip Niek Linnenbank
2019-12-04 16:53   ` Philippe Mathieu-Daudé
2019-12-04 20:44     ` Niek Linnenbank
2019-12-10  9:02   ` Philippe Mathieu-Daudé
2019-12-10 19:17     ` Niek Linnenbank
2019-12-02 21:09 ` [PATCH 02/10] hw: arm: add Xunlong Orange Pi PC machine Niek Linnenbank
2019-12-03  9:17   ` Philippe Mathieu-Daudé
2019-12-03 19:33     ` Niek Linnenbank
2019-12-04  9:03       ` Philippe Mathieu-Daudé
2019-12-04 19:50         ` Niek Linnenbank
2019-12-05 22:15     ` Niek Linnenbank
2019-12-06  5:41       ` Philippe Mathieu-Daudé
2019-12-06 22:15         ` Niek Linnenbank
2019-12-10  8:59           ` Philippe Mathieu-Daudé
2019-12-10 19:14             ` Niek Linnenbank
2019-12-02 21:09 ` [PATCH 03/10] arm: allwinner-h3: add Clock Control Unit Niek Linnenbank
2019-12-13  0:03   ` Philippe Mathieu-Daudé
2019-12-02 21:09 ` [PATCH 04/10] arm: allwinner-h3: add USB host controller Niek Linnenbank
2019-12-04 16:11   ` Aleksandar Markovic
2019-12-04 20:20     ` Niek Linnenbank
2019-12-10  7:56   ` Philippe Mathieu-Daudé
2019-12-10  8:29     ` Gerd Hoffmann
2019-12-10 19:11       ` Niek Linnenbank
2019-12-02 21:09 ` [PATCH 05/10] arm: allwinner-h3: add System Control module Niek Linnenbank
2019-12-13  0:09   ` Philippe Mathieu-Daudé
2019-12-15 23:27     ` Niek Linnenbank
2019-12-16  0:17       ` Philippe Mathieu-Daudé
2019-12-02 21:09 ` [PATCH 06/10] arm/arm-powerctl: set NSACR.{CP11, CP10} bits in arm_set_cpu_on() Niek Linnenbank
2019-12-06 14:24   ` Peter Maydell
2019-12-06 20:01     ` Niek Linnenbank
2019-12-13 20:52       ` Niek Linnenbank
2019-12-02 21:09 ` [PATCH 07/10] arm: allwinner-h3: add CPU Configuration module Niek Linnenbank
2019-12-02 21:09 ` [PATCH 08/10] arm: allwinner-h3: add Security Identifier device Niek Linnenbank
2019-12-06 14:27   ` Peter Maydell
2019-12-06 16:35     ` Philippe Mathieu-Daudé
2019-12-06 20:20       ` Niek Linnenbank [this message]
2019-12-02 21:09 ` [PATCH 09/10] arm: allwinner-h3: add SD/MMC host controller Niek Linnenbank
2019-12-11 22:34   ` Niek Linnenbank
2019-12-12 23:56     ` Philippe Mathieu-Daudé
2019-12-13 21:00       ` Niek Linnenbank
2019-12-14 13:59         ` Philippe Mathieu-Daudé
2019-12-14 20:32           ` Niek Linnenbank
2019-12-15 23:07       ` Niek Linnenbank
2019-12-16  0:14         ` Philippe Mathieu-Daudé
2019-12-16 19:46           ` Niek Linnenbank
2019-12-16 21:28             ` Philippe Mathieu-Daudé
2019-12-02 21:09 ` [PATCH 10/10] arm: allwinner-h3: add EMAC ethernet device Niek Linnenbank
2019-12-03  9:33   ` KONRAD Frederic
2019-12-03 19:41     ` Niek Linnenbank
2019-12-04 15:14     ` Philippe Mathieu-Daudé
2019-12-04 15:22       ` KONRAD Frederic
2019-12-03  8:47 ` [PATCH 00/10] Add Allwinner H3 SoC and Orange Pi PC Machine Philippe Mathieu-Daudé
2019-12-03 19:25   ` Niek Linnenbank
2019-12-10  8:40     ` Philippe Mathieu-Daudé
2019-12-09 21:37   ` Niek Linnenbank
2019-12-10  8:26     ` Philippe Mathieu-Daudé
2019-12-10 20:12       ` Niek Linnenbank
2019-12-12 23:07         ` Niek Linnenbank
2019-12-12 23:25           ` Philippe Mathieu-Daudé
2019-12-13 20:45             ` Niek Linnenbank
2019-12-03  9:02 ` Philippe Mathieu-Daudé
2019-12-03 19:32   ` Niek Linnenbank
2019-12-06 14:16     ` Peter Maydell
2019-12-09 22:24       ` Aleksandar Markovic
2019-12-10 10:34 ` KONRAD Frederic
2019-12-10 19:55   ` Niek Linnenbank

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