From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761613AbYDUPzB (ORCPT ); Mon, 21 Apr 2008 11:55:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751399AbYDUPyx (ORCPT ); Mon, 21 Apr 2008 11:54:53 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:57564 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751284AbYDUPyw (ORCPT ); Mon, 21 Apr 2008 11:54:52 -0400 Subject: Re: [PATCH 1/2] OLPC: Add support for calling into Open Firmware From: David Woodhouse To: Andres Salomon Cc: Mitch Bradley , Yinghai Lu , "H. Peter Anvin" , "Eric W. Biederman" , Ingo Molnar , Andrew Morton , Joseph Fannin , linux-kernel@vger.kernel.org, jordan.crouse@amd.com In-Reply-To: <20080421102417.6de71391@ephemeral> References: <20080418014757.52fb4a4f.akpm@linux-foundation.org> <20080419031024.GC3503@nineveh.local> <20080418202925.b18452c5.akpm@linux-foundation.org> <20080419092544.378664a8@ephemeral> <20080419133909.5aa6b63e@ephemeral> <86802c440804200334t5cdcd100rfc41e9b1bf379109@mail.gmail.com> <480C0582.9010509@firmworks.com> <86802c440804202015h2605eff7vc733874dd1f22261@mail.gmail.com> <480C1286.3040307@firmworks.com> <20080421102417.6de71391@ephemeral> Content-Type: text/plain Date: Mon, 21 Apr 2008 16:54:13 +0100 Message-Id: <1208793253.9212.507.camel@pmac.infradead.org> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1 (2.22.1-1.fc9) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2008-04-21 at 10:24 -0400, Andres Salomon wrote: > I'm not actually convinced that we *do* want to keep OFW resident in memory, > especially given the memory tricks we need to play. I also don't actually > like the OFW interface that we. The debugging aspect of it was a > compelling argument up until a week ago (when kernel debuggers started > finally finding their way into the kernel). I don't actually think that the debugging aspect was _ever_ a compelling argument. It might have made it theoretically possible for _Mitch_ to debug kernel problems, should he be inclined to do so -- but for the rest of us mere mortals it's just a PITA trying to keep OpenFirmware live. A gdb stub is much more useful, in my experience. > However, until we clean up the promfs stuff, there's no chance of getting > an OFW device tree upstream. I see no reason why we shouldn't be able to create a 'flattened' device-tree during early boot, like the PowerPC kernel does. And use it thereafter, having quiesced OpenFirmware. Haven't we already been working on unifying this between SPARC and PowerPC kernels? I definitely don't think we need to play these tricks to keep OpenFirmware resident while the kernel is running. Take a look at your second patch -- it's _all_ just lookups in the device-tree, and you're inventing a new way to do it instead of using the existing one. -- dwmw2