From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Herrenschmidt Subject: Re: [Power.org:parch] devicetree: Musings on reserved regions Date: Tue, 08 Feb 2011 17:45:21 +1100 Message-ID: <1297147521.14982.192.camel@pasglop> References: <1297114766.14982.76.camel@pasglop> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org To: Grant Likely Cc: "parch-QRwYI7m9GJLYtjvyW6yDsg@public.gmane.org" , devicetree-discuss , David Gibson , Stuart Yoder , Scott Wood , Matthew McClintock List-Id: devicetree@vger.kernel.org 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.