[Power.org:parch] devicetree: Musings on reserved regions

[Benjamin Herrenschmidt]

On Mon, 2011-02-07 at 22:05 -0700, Grant Likely wrote:
> 
> Hmmm, of all the ideas, I think I like this one the best.  It is a
> little more verbose than I was thinking, but making each reserved
> region (or set of reserved regions) have separate node has some very
> real advantages.  For one, the address decoding *just works* with our
> existing helpers.  Also it means that device nodes can directly
> indicate the reserved regions associated with it by way of a phandle.

But that means that anything that needs to setup a simple memory
allocator (and thus needs to know what to avoid) will need to walk the
entire tree for nodes with a "reserved" property, be able to parse
addresses down to that node (not always obvious accross some bus types),
etc...

Or do we propose to keep a "consolidated" reserve map in addition to
having nodes self-describe which part of this reserve map they are
responsible for, which thus gives the OS the option to:

 - Reserve it all
 - Then, based on specific knowledge of some nodes, maybe release
or juts "tag" (for diag purposes) portions of reserved memory

Ben.