Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757071Ab3G3Ef0 (ORCPT ); Tue, 30 Jul 2013 00:35:26 -0400 Received: from mail-oa0-f50.google.com ([209.85.219.50]:33353 "EHLO mail-oa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753072Ab3G3EfY (ORCPT ); Tue, 30 Jul 2013 00:35:24 -0400 MIME-Version: 1.0 In-Reply-To: <20130730032926.GL29970@voom.fritz.box> References: <51F39FD8.6080808@broadcom.com> <2460092.aLmjrOVh1g@flatron> <51F3A82E.2000907@broadcom.com> <1374988276.1973.29.camel@dabdike> <20130730014453.GJ29970@voom.fritz.box> <20130730032926.GL29970@voom.fritz.box> From: Grant Likely Date: Mon, 29 Jul 2013 22:35:03 -0600 X-Google-Sender-Auth: P4-7rp4NnjGYNpHpKAVR3czRMaA Message-ID: Subject: Re: [Ksummit-2013-discuss] DT bindings as ABI [was: Do we have people interested in device tree janitoring / cleanup?] To: Maxime Ripard Cc: Richard Cochran , Tomasz Figa , Arend van Spriel , Olof Johansson , Mark Brown , Mark Rutland , "devicetree@vger.kernel.org" , "ksummit-2013-discuss@lists.linuxfoundation.org" , Russell King - ARM Linux , Ian Campbell , Pawel Moll , Stephen Warren , Domenico Andreoli , "rob.herring@calxeda.com" , "linux-kernel@vger.kernel.org" , Jason Gunthorpe , Dave P Martin , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1736 Lines: 48 On Mon, Jul 29, 2013 at 1:31 AM, Maxime Ripard wrote: > Hi, > > On Sun, Jul 28, 2013 at 03:19:03PM +0200, Richard Cochran wrote: >> On Sun, Jul 28, 2013 at 11:12:53AM +0200, Tomasz Figa wrote: >> >> > I'm not really sure what effect on users this has. Maybe you should define >> > "users". >> >> ... >> >> > Care to explain this reasoning? >> >> Use Case >> ~~~~~~~~ >> >> User acquires a machine running ARM Linux version 3.x, with u-boot >> and dtb in a read only flash partition. The board boots and works just >> fine. However, for his application, the user requires a new kernel >> feature that appeared in version 3.y where y > x. He compiles the new >> kernel, and it also works. > > I'm afraid this kind of use case will never be properly supported, DT > stable ABI or not. Why? New kernel features should be no problem at all. New driver features /might/ not be available, but only if the new feature requires additional data that isn't present in the tree and cannot be obtained elsewhere. > > Think about this: what kernel will actually be shipped in that board? > Most likely, it will be a BSP kernel from the vendor. Does the vendor > will have made that commitment to have a stable ABI for the DT? Will it > use the same bindings than mainline? Do we want to support all the crazy > bindings every vendor will come up with? That's not a DT issue. That an out-of-tree board/SoC support issue. DT doesn't make that any better or worse. g. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/