From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from AGRXSUSMAILB.smiths.aero (host241-chi.smiths-group.com [65.216.75.241]) by ozlabs.org (Postfix) with ESMTP id 4F727DDD08 for ; Thu, 15 Mar 2007 08:11:17 +1100 (EST) Message-ID: <45F864E8.40501@smiths-aerospace.com> Date: Wed, 14 Mar 2007 17:11:04 -0400 From: Jerry Van Baren MIME-Version: 1.0 To: Timur Tabi Subject: Re: [dtc] Add support for flat device tree format version 17 References: <20070313062240.GA22737@localhost.localdomain> <45F863DF.5050709@freescale.com> In-Reply-To: <45F863DF.5050709@freescale.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Timur Tabi wrote: > David Gibson wrote: >> libfdt defined a new version of the flattened device tree format, >> version 17. It is backwards compatible with version 16, just adding >> an extra header field giving the size of the blob's structure blob. > > Question: > > Since the DTB is compatible with V16, then technically U-Boot can work with it. What > would happen if U-Boot added some nodes to the DTB, but it didn't update size_dt_struct? > Would the value of size_dt_struct still be correct? If not, then does that mean that > U-Boot should reject V17 DTBs? Ahh, now I see your concern and don't know the answer at this point. The best solution, which I'm making progress on but slowly, is to pull David Gibson's libfdt utilities into u-boot and use them to manipulate the tree. I very much want v17 blobs because that removes my "write-in-place" restrictions on changing the properties. gvb