From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757248AbXGIPb7 (ORCPT ); Mon, 9 Jul 2007 11:31:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754104AbXGIPbw (ORCPT ); Mon, 9 Jul 2007 11:31:52 -0400 Received: from [212.12.190.92] ([212.12.190.92]:34229 "EHLO raad.intranet" rhost-flags-FAIL-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1753740AbXGIPbv (ORCPT ); Mon, 9 Jul 2007 11:31:51 -0400 From: Al Boldi To: Pavel Machek , Nick Piggin Subject: Re: Hibernation Redesign Date: Mon, 9 Jul 2007 18:30:48 +0300 User-Agent: KMail/1.5 Cc: Jeremy Maitin-Shepard , linux-kernel@vger.kernel.org, Andrew Morton References: <200707081737.21932.a1426z@gawab.com> <4691BC0F.8050909@yahoo.com.au> <20070709135205.GB3216@elf.ucw.cz> In-Reply-To: <20070709135205.GB3216@elf.ucw.cz> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200707091830.48074.a1426z@gawab.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Pavel Machek wrote: > > >>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. Interesting proposition, which may actually work. Thanks! > > >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. Who said we need two kernels? You could inline it like Xen, which would give you one kernel with two modes: normal and hibernate. Thanks! -- Al