[PATCH v2 0/8] efi_loader: improve device-tree loading

[Ilias Apalodimas]

Hi Simon,

[...]

> > >>>
> > >>
> > >
> > > Can we use the best-match compatible approach as expected by the new
> > > 'make image.fit' in Linux?
> > >
> > > Filenames should be deprecated IMO. I am happy to help work on how to
> > > do that if you agree.
> >
> > Hello Simon,
> >
> > It is the OS that creates boot options. The OS can determine the exact
> > dtb file based on the compatible string and the kernel version once per
> > kernel upgrade. This is much more efficient than doing the same on every
> > boot.
> >
> > Replacing $fdtfile by a matching logic could make sense. But please
> > consider the effect on boot time if have to read through more than 1000
> > arm64 dtbs with U-Boot's non-caching file-system drivers.
>
> The suggested option here is to use FIT, which is very fast at
> scanning the files. Please see [1]
>
> Failing that, we could implement a way (in FIT) of specifying that the
> FDT is in an external file. In that case FIT would become a mapping
> from compatible strings to filenames.

This is kind of irrelevant to FIT. This is how the efibootmgr
configures the files it has to load.
commit 76e8acce12fe,  commit 53f6a5aa8626, and
doc/develop/uefi/uefi.rst, Chapter Load file 2 protocol has enough
information of how the initrd is implemented. What Heinrich is doing
here is extending the existing code to load a DT

Regards
/Ilias

>
> Regards,
> Simon
>
> [1] https://github.com/open-source-firmware/flat-image-tree/blob/main/source/chapter3-usage.rst