From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755976AbXGIPXY (ORCPT ); Mon, 9 Jul 2007 11:23:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751581AbXGIPXQ (ORCPT ); Mon, 9 Jul 2007 11:23:16 -0400 Received: from sccrmhc12.comcast.net ([204.127.200.82]:39654 "EHLO sccrmhc12.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750796AbXGIPXP (ORCPT ); Mon, 9 Jul 2007 11:23:15 -0400 From: Jeremy Maitin-Shepard To: Pavel Machek Cc: david@lang.hm, Benjamin Herrenschmidt , "Rafael J. Wysocki" , Alan Stern , Kyle Moffett , Nigel Cunningham , Matthew Garrett , linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org Subject: Re: hibernation/snapshot design References: <200707082115.27363.rjw@sisk.pl> <1183928612.3388.289.camel@localhost.localdomain> <200707082345.27859.rjw@sisk.pl> <1183931688.3388.316.camel@localhost.localdomain> <20070708221315.GF5401@elf.ucw.cz> <20070708230042.GH5401@elf.ucw.cz> <20070708232819.GJ5401@elf.ucw.cz> X-Habeas-SWE-9: mark in spam to . X-Habeas-SWE-8: Message (HCM) and not spam. Please report use of this X-Habeas-SWE-7: warrant mark warrants that this is a Habeas Compliant X-Habeas-SWE-6: email in exchange for a license for this Habeas X-Habeas-SWE-5: Sender Warranted Email (SWE) (tm). The sender of this X-Habeas-SWE-4: Copyright 2002 Habeas (tm) X-Habeas-SWE-3: like Habeas SWE (tm) X-Habeas-SWE-2: brightly anticipated X-Habeas-SWE-1: winter into spring Date: Mon, 09 Jul 2007 11:23:12 -0400 In-Reply-To: <20070708232819.GJ5401@elf.ucw.cz> (Pavel Machek's message of "Mon\, 9 Jul 2007 01\:28\:19 +0200") Message-ID: <873azxwqhr.fsf@jbms.ath.cx> User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.0.990 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Pavel Machek writes: [snip] >> why do you say that neither would work for the "lets hibernate my >> notebook" case? > Both would work. One would eat 8-64MB of your RAM, permanently; As I have stated in other messages, the kdump approach would not waste any RAM permanently. The reason that kdump must reserve memory at boot is that on panic, it cannot attempt to nicely stop drivers, and consequently there might be ongoing DMAs that could clobber anything but the reserved area; this reason does not apply to hibernate, though. I'll quote a previous message in which I stated a solution that can be used: Immediately before jumping to the new kernel, the first X bytes (where X is the amount of memory the new kernel will get, typically 16MB or 64MB) of physical memory are backed up into the arbitrary discontiguous pages that are made available. This will not take very long, because copying even 64MB of memory is extremely fast. Then the new kernel is free to use the first X bytes of contiguous physical memory. Problem solved. -- Jeremy Maitin-Shepard