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Date: Wed, 22 Jun 2016 17:06:33 +0200
From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: Richard Weinberger <richard@nod.at>
Cc: "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>, Artem
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 <ezequiel@vanguardiasur.com.ar>
Subject: Re: [RFC] Raising the UBI version
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On Wed, 22 Jun 2016 16:59:50 +0200
Richard Weinberger <richard@nod.at> wrote:

> Am 22.06.2016 um 16:52 schrieb Boris Brezillon:
> > So how about defining the following:
> > - /sys/class/ubi/version: user-space ABI version (should always be one)  
> 
> Yes. To not break libubi.
> 
> > - /sys/class/ubi/supported-on-flash-formats: either a bitfield or an
> >   integer representing the higher on-flash format version supported by
> >   the implementation (which implies that implementations have to
> >   support all on-flash formats up-to supported-on-flash-formats)  
> 
> We can do that. But who will evaluate this file?

ubiformat may need that one to check if the provided ubi image is
supported by the implementation.

> 
> > - /sys/class/ubi/supported-features: the features supported by the
> >   implementation (each bit is a specific feature or a set of features).
> >   The features may or may not be version dependent.
> > - /sys/class/ubi/ubiX/on-flash-format: the on-flash format used on the
> >   UBIX device
> > - /sys/class/ubi/ubiX/features: the features exposed by this UBIX
> >   device  
> 
> I think we should make features depend on version = 2.
> IOW when we change the UBI format in a major way version will be 3 and
> we maybe use something else to expose features.

IIUC, we move to version 2 now, because we're using one of the padding
byte (word?) to expose the feature flags, correct?
It makes sense.