From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758564AbXGOWao (ORCPT ); Sun, 15 Jul 2007 18:30:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753742AbXGOWag (ORCPT ); Sun, 15 Jul 2007 18:30:36 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:40156 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752582AbXGOWaf (ORCPT ); Sun, 15 Jul 2007 18:30:35 -0400 From: "Rafael J. Wysocki" To: "Dr. David Alan Gilbert" Subject: Re: Hibernation considerations Date: Mon, 16 Jul 2007 00:38:11 +0200 User-Agent: KMail/1.9.5 Cc: LKML , Alan Stern , Andrew Morton , "Eric W. Biederman" , "Huang, Ying" , Jeremy Maitin-Shepard , Kyle Moffett , Nigel Cunningham , Pavel Machek , pm list , david@lang.hm, Al Boldi References: <200707151433.34625.rjw@sisk.pl> <20070715125855.GA1737@gallifrey> In-Reply-To: <20070715125855.GA1737@gallifrey> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707160038.12943.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sunday, 15 July 2007 14:58, Dr. David Alan Gilbert wrote: > * Rafael J. Wysocki (rjw@sisk.pl) wrote: > > > (5) Hibernation should be transparent from the applications' point of view > > > > Generally, applications should not notice that hibernation took place. > > [Note that I don't regard all processes as applications and I think that > > there may be processes which need to handle the hibernation in a special > > way.] Ideally, for example, if some audio is being played when a > > hibernation starts, the audio player should be able to continue playing the > > same audio after the restore from the point in which it has been > > interrupted by the hibernation. Also, the CPU affinities and similar > > That would be _so_ embarrassing in a library; I'd rather the audio > player had the opportunity to consider whether restarting was a good idea. > > > (6) State of devices from before hibernation should be restored, if possible > > > > If possible, during a restore devices should be brought back to the same > > state in which they were before the corresponding hibernation. Of course > > in some situations it might be impossible to do that (eg. the user > > connected the hibernated system to a different IP subnet and then > > restored), but as a general rule, we should do our best to restore the > > state of devices, which is directly related to point (5) above. > > Or the user unplugs their flash drive after hibernation rather than before. > > Two things which I think would be nice to consider are: > 1) Encryption - I'd actually prefer if my luks device did not > remember the key accross a hibernation; I want to be forced to > reenter the phrase. However I don't know what the best thing > to do to partitions/applications using the luks device is. Encryption is possible with both the userland hibernation (aka uswsusp) and TuxOnIce (formerly known as suspend2). Still, I don't consider it as a "must have" feature for a framework to be generally useful (many users don't use it anyway). > 2) Some level of debugging needs to be available so that users can > provide something so you can see why something hasn't hibernated > or why (as in the case of this tosh laptop) it still takes power > during hibernation. I agree. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth