From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757074AbXGINw1 (ORCPT ); Mon, 9 Jul 2007 09:52:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752998AbXGINwV (ORCPT ); Mon, 9 Jul 2007 09:52:21 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:48535 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751578AbXGINwU (ORCPT ); Mon, 9 Jul 2007 09:52:20 -0400 Date: Mon, 9 Jul 2007 15:52:05 +0200 From: Pavel Machek To: Nick Piggin Cc: Jeremy Maitin-Shepard , Al Boldi , linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: Hibernation Redesign Message-ID: <20070709135205.GB3216@elf.ucw.cz> References: <200707081737.21932.a1426z@gawab.com> <87tzsew712.fsf@jbms.ath.cx> <4691B9A5.6060203@yahoo.com.au> <4691BC0F.8050909@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4691BC0F.8050909@yahoo.com.au> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.11+cvs20060126 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > >>from a *new* kernel space/user space that is created by loading a new > >>kernel in a manner similar to what is done for kexec crashdumps. Unlike > >>kexec crashdumps, however, it would not require reserving any memory at > >>boot, because the necessary memory (maybe 16MB or 64MB) can be freed > >>just before hibernating, and device drivers can be properly stopped so > >>that DMAs don't stomp over certain memory. > > > > > >This is the Morton method, isn't it? :) I remember it sounding like a > >very good idea when he brought it up, but I can't remember the details > >of why it was rejected or what the problems were. > > Hmm, and it seems like I won't get to know without reliving what > looks like an epic flamewar starting.... here: > > http://thread.gmane.org/gmane.linux.kernel/374889 > > However from a quick look it seems like the only reason is the RAM > overhead of a reserve area. It seems unfortunate that it was > dismissed so quickly because of that problem (which could be > improved). Well, the kexec thingy should be able to hibernate a machine, but it will not be "software-suspend" any more, and it may be quite a lot of work to get it going. In the end, you'll get rid of freezer problems, but will have two kernels to care about, and certainly more conventional design. I do not think I have time to try that (and don't think freezer problems are _that_ bad in the first place), but some interested soul could certainly try it. If we deprecate swsusp in 2.6.45 or so, I do not think I'll be crying. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html