[U-Boot] [PATCH v9 2/2] Odroid-XU3: Add documentation for Odroid-XU3

[Javier Martinez Canillas]

Hello Lukasz,

On Fri, Nov 28, 2014 at 9:39 AM, Lukasz Majewski <l.majewski at majess.pl> wrote:
>> I have yet to take him up on that offer though, but it sounds like a
>> good way forward. The current layout really isn't practical.
>>
>
> It indeed isn't very practical, but this is what you received from
> HardKernel when you buy XU3 board.
>
> Of course you can grab their sources, modify the layout, prepare
> u-boot's SPL and send it to them to be signed.
> However, it is not the way the "normal" user do things.
>
> He or she would like to replace standard (and outdated) HardKernel
> u-boot on their SD card and go forward with booting kernel.
>

I agree with Sjoed that normal users don't replace the low-level
components that are provided by the board vendor.

After all you can boot a mainline kernel using the vendor u-boot, just
append the DTB and create a uImage. The practical reason why someone
would want to replace the vendor u-boot is to have more features but
is very hard to do if there is a constraint in the maximum u-boot
image size (even harder if the maximum is such small like in the XU3).

> For now we _must_ focus on supporting XU3 with default BL1/BL2 and hence
> we are obliged to have u-boot size smaller than 328 KiB.
>
> It is challenging but for sure doable.
>

It is doable but I don't see why the default BL2 _must_ be used.

A user that wants to replace the kernel or u-boot is already tech-savy
and can for sure replace the BL2 as well if it's publicly available.
Maybe hardkernel folks can even make the modified BL2 available on
their website and the link added in the comment explaining the layout?

Also, it is an artificial constraint after all and can be easily
modified. In fact I think we should push hardkernel to change that
layout by default and use a BL2/SPL that has more sensible size for
the u-boot binary even if they don't need it for their vendor u-boot
which seems to be quite small.

> Best regards,
> Lukasz Majewski
>

Best regards,
Javier