From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756072Ab1BASge (ORCPT ); Tue, 1 Feb 2011 13:36:34 -0500 Received: from LUNGE.MIT.EDU ([18.54.1.69]:56734 "EHLO lunge.queued.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752664Ab1BASgd (ORCPT ); Tue, 1 Feb 2011 13:36:33 -0500 Date: Tue, 1 Feb 2011 10:36:17 -0800 From: Andres Salomon To: Sebastian Andrzej Siewior Cc: Daniel Drake , Grant Likely , linux-kernel@vger.kernel.org, sodaville@linutronix.de, x86@kernel.org, dirk.brandewie@gmail.com Subject: Re: [PATCH v2 01/15] x86/e820: remove conditional early mapping in parse_e820_ext Message-ID: <20110201103617.2c3aa118@debxo> In-Reply-To: <4D4808D2.3080701@linutronix.de> References: <1292600033-12271-1-git-send-email-bigeasy@linutronix.de> <1292600033-12271-2-git-send-email-bigeasy@linutronix.de> <20101230083745.GC11721@angua.secretlab.ca> <20110104130839.GA21359@www.tglx.de> <20110114081446.GC21832@angua.secretlab.ca> <20110114105709.GA7562@www.tglx.de> <20110114134345.712e2e29@queued.net> <4D4808D2.3080701@linutronix.de> X-Mailer: Claws Mail 3.7.6 (GTK+ 2.20.1; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 01 Feb 2011 14:21:22 +0100 Sebastian Andrzej Siewior wrote: > Daniel Drake wrote: > > Hi, > Hi, > > > Context: https://patchwork.kernel.org/patch/450681/ > > > > This patch will indeed cause problems for OLPC. Thanks for bringing > > it to our attention. > > > > On OLPC, the device tree is not used as a source of devices like on > > other platforms, it is simply used to present information to the > > kernel and userspace (in read-only fashion). > > > > If I understand it correctly, the above patch is saying: if we have > > a device tree, don't add the standard x86 RTC device. > Yes. > > > However, what we need it to say is: if we have a device tree *and* > > the device tree is being used as a source of devices, don't add the > > standard x86 RTC device. > > > > Therefore in the OLPC case, this particular bail-out condition will > > never be met, because the device tree is not being used as a source > > of devices. > So it is not case now. Will it ever be? > That is unclear. For now, it's not, and there aren't plans to make it so. > > > > Does that make sense? > > I don't quite get how or what for do you use the device tree. Could > you please answer me the following questions: > - is the variable allnodes NULL in your case? No. > - variable initial_boot_params should be NULL in your case, right? Yes. > - how should I checked for "device tree is being used as a source of > devices"? The nodes on in the device tree are not probed unless one > calls of_platform_bus_probe() with a few ids. However I do this now > unconditionally which is not a problem unless you have a device > tree ... Perhaps it should be specifically checking for a fdt (by way of initial_boot_params)? Sparc also does not have initial_boot_params, so one might even be able to drop an #ifdef in the process.