[U-Boot] [PATCH v3 05/19] SPL: FIT: allow loading multiple images

[Dr. Philipp Tomsich]

> On 03 Apr 2017, at 12:05, Andre Przywara <andre.przywara at arm.com> wrote:
> 
> On 03/04/17 10:40, Lukasz Majewski wrote:
>> Hi Andre ,
>> 
>>> So far we were not using the FIT image format to its full potential:
>>> The SPL FIT loader was just loading the first image from the /images
>>> node plus one of the listed DTBs.
>>> Now with the refactored loader code it's easy to load an arbitrary
>>> number of images in addition to the two mentioned above.
>>> As described in the FIT image source file format description, iterate
>>> over all images listed at the "loadables" property in the
>>> configuration node and load every image at its desired location.
>>> This allows to load any kind of images:
>>> - firmware images to execute before U-Boot proper (for instance
>>>  ARM Trusted Firmware (ATF))
>>> - firmware images for management processors (SCP, arisc, ...)
>>> - firmware images for devices like WiFi controllers
>>> - bit files for FPGAs
>>> - additional configuration data
>>> - kernels and/or ramdisks
>> 
>> Would it be possible to adopt this code to also load SDRAM controller
>> configuration data?
> 
> As it stands at the moment, this code is run when the SPL is finished
> with initialising the platform and is about to load and hand over to
> U-Boot proper.
> It would need to be investigated if the device driver required to
> actually load the FIT image works without DRAM being available (as in:
> do we have enough heap and stack, for instance).
> Also I am not sure the FIT (fdt) parsing code is really tuned for low
> memory, since normally it runs with DRAM already available.
> 
> So while this doesn't sound impossible, it's probably some work ahead,
> depending on the resource limitation you have in SPL on your platform.

The more general solution would be to move towards having a TPL in
addition to the SPL…

Regards,
Philipp.