On Thu, Apr 23, 2009 at 05:50:05PM +0400, Anton Vorontsov wrote:

As for Freescale parts, all the reference board I've seen were
very friendly wrt upgrading their device-trees, i.e. none of
the boards were shipping with device-tree soldered into the
firmware.

But many of them have broken when a dtb that u-boot didn't like was
inserted.

And note that most developers are using up-to-date firmwares
(U-Boots), device trees, and kernels. 

So then why did we have to make cuImage?

And that means that old device-tree + new kernel combination is left
untested for years. And untested stuff is broken stuff, by definition.

There's a difference between risking that something may be broken, and
gratuitously making it broken.

Sure, there is a completely different story wrt device-tree
changes that might break firmwares. And that I believe we'd
better avoid. For example device_type = "soc", if removed,
most firmwares would not fix-up {clock,bus}-frequency properties.

Even if the given change may not break the firmware, it could force an
update in which a prior change breaks the firmware.

-Scott