[PATCH 1/2] Documentation: devicetree: root node serial-number property documentation

[contact@paulk.fr (Paul Kocialkowski)]

Le jeudi 16 avril 2015 ? 10:23 -0500, Kumar Gala a ?crit :
> > On Apr 16, 2015, at 9:36 AM, Rob Herring <robherring2@gmail.com> wrote:
> > 
> > On Thu, Apr 16, 2015 at 4:10 AM, Paul Kocialkowski <contact@paulk.fr> wrote:
> >> Le jeudi 16 avril 2015 ? 09:56 +0200, Stefan Agner a ?crit :
> >>> On 2015-03-28 18:39, Paul Kocialkowski wrote:
> >>>> Signed-off-by: Paul Kocialkowski <contact@paulk.fr>
> >>> 
> >>> I think this is a worthwhile standardization.
> >>> 
> >>> Acked-by: Stefan Agner <stefan@agner.ch>
> >> 
> >> Thanks! I should also add a commit message in v2 mentioning that this is
> >> already used in open firmware and reported by lshw.
> > 
> > With that,
> > 
> > Acked-by: Rob Herring <robh@kernel.org>

[snip]

> I feel like this is a little lite either in the doc or commit message.
> Is the string completely arbitrary?  Is it meant to match labeling on
> a board or case?  Is this meant to be used by the kernel at all?

I guess it doesn't really matter what it is, as long as it's a string.
The kernel does not suggest any use for it either, it's just made
available to userspace through cpuinfo.

Now if there is a particular use for this in user-space, it would have
to match some standards. For instance, it Android, ro.serialno is
usually a 16-bytes (plus one null byte) representation of a 64 bit
number. For USB, I recall it is usually a 32 bytes string (including the
null byte), but may be extended to more.

What the string actually represents depends and some SOCs have serial
number bytes (I know that omap and sunxi have some for instance, that
are usually used) while other devices may take it from somewhere else.
In any case, it doesn't really matter and is not up to the kernel anyway
since it is just passed through from the bootloader.

Thus, I don't think it's very relevant to mention it in either the
documentation or the commit message.

-- 
Paul Kocialkowski, Replicant developer

Replicant is a fully free Android distribution running on several
devices, a free software mobile operating system putting the emphasis on
freedom and privacy/security.

Website: http://www.replicant.us/
Blog: http://blog.replicant.us/
Wiki/tracker/forums: http://redmine.replicant.us/

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