Re: [PATCH V5 5/5] of: unittest: Statically apply overlays using fdtoverlay

[Viresh Kumar]

On 20-01-21, 23:14, Frank Rowand wrote:
> It is a convenient FDT to use because it provides the frame that the overlays
> require to be applied.  It is fortunate that fdtoverlay does not reject the use
> of an FDT with overlay metadata as the base blob.

> This is probably a good idea instead of depending on the leniency of fdtoverlay.

I believe fdtoverlay allows that intentionally, that would be required
for the cases where we have a hierarchy of extension boards or
overlays.

A platform can have a base dtb (with /plugin/;), then we can have an
overlay (1) for an extension board (with /plugin/;) and then an
overlay (2) for an extension board for the previous extension board.

In such a case overlay-(2) can't be applied directly to the base dtb
as it may not find all the nodes it is trying to update. And so
overlay-(2) needs to be applied to overlay-(1) and then the output of
this can be applied to the base dtb.

This is very similar to what I tried with the intermediate.dtb
earlier.

-- 
viresh