From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: Hibernation considerations Date: Tue, 17 Jul 2007 23:45:42 +0200 Message-ID: <200707172345.43574.rjw@sisk.pl> References: <871wf6g1q1.fsf@jbms.ath.cx> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <871wf6g1q1.fsf@jbms.ath.cx> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-pm-bounces@lists.linux-foundation.org Errors-To: linux-pm-bounces@lists.linux-foundation.org To: Jeremy Maitin-Shepard Cc: david@lang.hm, LKML , Kyle Moffett , Al Boldi , "Eric W. Biederman" , Pavel Machek , "Huang, Ying" , Andrew Morton , pm list List-Id: linux-pm@vger.kernel.org On Tuesday, 17 July 2007 23:27, Jeremy Maitin-Shepard wrote: > david@lang.hm writes: > > [snip] > > >> How do you guarantee that no tasks are scheduled when you get back to the > >> hibernated kernel? > > > just don't schedule any userspace tasks. all you need to do is to execute the > > ACPI sleep functions. you normally do that after stopping userspace > > anyway. > > What does "stopping userspace" mean? You already said it does not mean > disabling interrupts. But using the freezer is also not an option, > since the avoidance of that is the main reason for the kexec approach in > the first place. > > [snip] > > >> Well, not exactly. If your battery runs out of power while you're suspended, > >> but you have the image saved, it's still better to restore from the image, > > even > >> if something may not work correctly after the restore, than to risk a loss of > >> data. > > > if things don't work correctly you are still risking the loss of data, the user > > just doesn't know it. > > It should be possible on any system to do a hibernate followed by a > shutdown (and then resume properly, without any problems). Thus, for > handling suspend to both, you resume as if the system had been shutdown, > rather than resuming as if the system came from S4. Exactly. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth