Re: [PATCH] powerpc: Create "rom" (MTD) device prpmc2800

[Segher Boessenkool <segher@kernel.crashing.org>]

>> I think some binary partition table format that can be
>> used by _all_ MTD consumers should be defined.  How
>> that table should be communicated to the kernel in the
>> device tree case we can discuss later, then.  Maybe
>> something as simple as storing it in flash, and have a
>> "partition-table-offset" property or something like that.
>>
>> This is something the MTD people will have to buy into
>> of course.
>
> I tought I saw some config option implying that there already existed
> an on-device partition table format for flashes.

Interesting.

> Doesn't help us for
> existing boards which don't expect such a setup, of course.

If they don't use a device tree yet, I don't see much
of a problem.  If they do already, that can be fixed,
too -- gradually.

> Incidentally, with either the partitions-described-by-properties, or
> the revised more-flexible partitions-described-by-subnodes format, I'm
> not seeing it as required that the whole of the flash address space be
> described.

Indeed.  It is fine to simply tell the OS "there is
some flash here, you figure out what to use it for".

> So it would certainly be possible to *only* describe the
> sections of the flash used by firmware.  But I'm suggesting that we
> optionally allow other partitions to be described for boards / systems
> which have strong conventions about how the flash is divided and where
> we don't have any other way of recording the partition layout short of
> hardcoding.

As long as it's optional there should be no harm in
that, of course.


Segher