On Apr 22, 2009, at 4:46 PM, Timur Tabi wrote:

Kumar Gala wrote:

quoted

The specific issue I'm talking about is the addition of new nodes  
that
might break old device trees.

New nodes or new properties?  The CPM nodes are not new.  On some  
device
trees, the original versions did not have a compatible property for  
the
CPM nodes (e.g. commit 0b5cf10691eb2c95a9126bf25f5e084d83d5d743).
Therefore, there are device trees out there that are missing some  
property.

Like I said earlier, if you can demonstrate that *all* of these device
tree would be broken with the latest kernel anyway, then we don't need
to worry about backwards compatibility.

I'm tired of debugging customer issues where the kernel is updated but
the firmware and device tree aren't.  IMHO, Kernel developers are
generally too lax when it comes to firmware and device tree backwards
compatibility, and I think that's wrong.

New nodes.  For example I've proposed a "local access window" node.   
Once I add it I plan on changing code to use it.  This will break an  
old device tree booting with the new kernel and I'm completely ok with  
that.

- k