From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936324AbXGQVQp (ORCPT ); Tue, 17 Jul 2007 17:16:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758480AbXGQVQf (ORCPT ); Tue, 17 Jul 2007 17:16:35 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:50406 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758957AbXGQVQe (ORCPT ); Tue, 17 Jul 2007 17:16:34 -0400 From: "Rafael J. Wysocki" To: david@lang.hm Subject: Re: Hibernation considerations Date: Tue, 17 Jul 2007 23:24:31 +0200 User-Agent: KMail/1.9.5 Cc: Jeremy Maitin-Shepard , Alan Stern , LKML , Andrew Morton , "Eric W. Biederman" , "Huang, Ying" , Kyle Moffett , Nigel Cunningham , Pavel Machek , pm list , Al Boldi References: <87odiag45q.fsf@jbms.ath.cx> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707172324.33285.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, 17 July 2007 22:37, david@lang.hm wrote: > On Tue, 17 Jul 2007, Jeremy Maitin-Shepard wrote: > > > "Rafael J. Wysocki" writes: > > > > [snip] > > > >>> Rafael, for those of us who aren't thoroughly familiar with all the ins > >>> and outs of the ACPI spec, could you please summarize a list of the > >>> ACPI calls needed in the second and third cases above? Indicate which > >>> ones need to be done from within the original kernel and which should > >>> be done from within a kexec'd hibernation kernel. > > > >> Sure. > > > >> In the third case (ie. transition to S4) we are supposed to do the following: > > > >> (1) Upon entering the sleep state, which IMO can be done _after_ the image > >> has been saved: > > > > I assume you mean "in order to enter the sleep state", rather than "upon > > entering the sleep state". I still don't understand what you mean by > > "which IMO can be done _after_ the image has been saved"; as far as I > > understand, the last step of this process, "make the platform enter S4", > > is almost like a shutdown as far as the kernel is concerned (except for > > the tiny detail of having to call those special ACPI methods on resume); > > consequently, it would seem that nothing can be done after that step. > > > >> * figure out which devices can wake up > >> * put devices into low power states (wake-up devices are placed in the Dx > >> states compatible with the wake capability, the others are powered off) > > this can't be done by the image-saving kernel if that kernel doesn't know > about the device. Good observation. :-) Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth