From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755428AbXABVkB (ORCPT ); Tue, 2 Jan 2007 16:40:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755427AbXABVkA (ORCPT ); Tue, 2 Jan 2007 16:40:00 -0500 Received: from gate.crashing.org ([63.228.1.57]:52413 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755426AbXABVkA (ORCPT ); Tue, 2 Jan 2007 16:40:00 -0500 In-Reply-To: <1167773556.6165.79.camel@localhost.localdomain> References: <459714A6.4000406@firmworks.com> <20061230.211941.74748799.davem@davemloft.net> <459784AD.1010308@firmworks.com> <1167709992.6165.18.camel@localhost.localdomain> <24a109a8fa0f45011daf3e2b55172392@kernel.crashing.org> <1167768735.6165.68.camel@localhost.localdomain> <1167773556.6165.79.camel@localhost.localdomain> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <578a242271c65db1cf8d85e943fab67a@kernel.crashing.org> Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, devel@laptop.org, David Miller , David Kahn , Mitch Bradley , jg@laptop.org From: Segher Boessenkool Subject: Re: [PATCH] Open Firmware device tree virtual filesystem Date: Tue, 2 Jan 2007 22:40:17 +0100 To: Benjamin Herrenschmidt X-Mailer: Apple Mail (2.623) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> The kernel doesn't care if one CPU is in OF land while the others >> are doing other stuff -- well you have to make sure the OF won't >> try to use a hardware device at the same time as the kernel, true. > > That statement alone hides an absolute can of worms btw ;-) Oh I know. With a sane OF implementation, things will work out fine though. >> I'm a bit concerned about the 100kB or so of data duplication >> (on a *quite big* device tree), and the extra code you need >> (all changes have to be done to both tree copies). Maybe >> I shouldn't be worried; still, it's obviously not a great >> idea to *require* any arch to get and keep a full copy of >> the tree -- it's wasteful and unnecessary. > > Well, big device-trees generally are on big machines with enough memory > not to care and the only platform I know where the DT can actually > change over time is IBM pSeries when doing DLPAR, in which case, OF is > dead, it all happens via magic HV/RTAS calls and the kernel is > -supposed- to maintain it's own copy and add/remove nodes from it. You're almost convincing me. I'll sleep on it a night. Segher