[U-Boot] [PATCH 5/6] cmd: mtdparts: support runtime generated mtdparts

[Michal Suchanek]

On 6 June 2016 at 09:48, Ladislav Michl <ladis at linux-mips.org> wrote:
> On Mon, Jun 06, 2016 at 09:08:47AM +0200, Michal Suchanek wrote:
>> On 5 June 2016 at 20:23, Ladislav Michl <ladis at linux-mips.org> wrote:

>> > Unless I'm missing something, partition layout is passed to the kernel
>> > from the bootloader. So if kernel ends up with a different layout than
>> > a bootloader, there's a bug somewhere and that should be fixed.
>>
>> That's not it. The problem is that if this patch changes the layout
>> then building u-boot before this patch gives one layout and after this
>> patch it gives another layout effectively changing the partitioning.
>> All to save a few megabytes of a several gigiabyte medium. And if you
>> say that people can always set the partitioning by hand then it
>> completely defeats the purpose of fine-tuning the default in the first
>> place.
>
> U-Boot never prevented people from shooting their own leg, therefore
> there's no 'feature' preventing them to change default layout. They
> are still free to do whatever they want it they find it useful.
> Also I'm not proposing to change layout for exiting boards, just
> proving way to do it. igep00x0 boards had buggy NAND support since
> begining, so while fixing that, let's do it right way. Note that
> this feature is completely optional.
>
>> If on the other hand Linux got support for sizing partitions in nand
>> pages or eraseblocks and a patch changed the mtdparts layout to use
>> the new units then either both u-boot and Linux support the units or
>> parsing the partition fails. So it's safe and flexible and more
>> general and probably even less work on u-boot's part.
>
> Okay, specifing size in therms of eraseblock would solve my problem
> and I have to admit I'm not aware such a thing exists. Any pointer to
> the patch introducing that change?
>

I am not aware of any. it's on the list of nice to have things I will
probably not get to,

Anyway, It's imho the place to put this code so that Linux does not
depend on u-boot for pre-chewing it's partition table to get the
partitions right.

Thanks

Michal