From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758753AbYENXrS (ORCPT ); Wed, 14 May 2008 19:47:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755124AbYENXrJ (ORCPT ); Wed, 14 May 2008 19:47:09 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:60516 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753440AbYENXrH (ORCPT ); Wed, 14 May 2008 19:47:07 -0400 From: "Rafael J. Wysocki" To: "Eric W. Biederman" Subject: Re: [linux-pm] [PATCH -mm] kexec jump -v9 Date: Thu, 15 May 2008 01:47:23 +0200 User-Agent: KMail/1.9.6 (enterprise 20070904.708012) Cc: Alan Stern , Pavel Machek , nigel@nigel.suspend2.net, Kexec Mailing List , linux-kernel@vger.kernel.org, Andrew Morton , linux-pm@lists.linux-foundation.org, Vivek Goyal , Len Brown References: <200803222229.45673.rjw@sisk.pl> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200805150147.24968.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, 15 of May 2008, Eric W. Biederman wrote: > "Rafael J. Wysocki" writes: > > > On Saturday, 22 of March 2008, Alan Stern wrote: > > > The spec doesn't say much about that, so we'll need to carry out some > > experiments. > > > Still, as far as I can figure out what the spec authors _might_ mean, I think > > that it would be inappropriate to restore the ACPI NVS area if S5 was entered > > on "power off". The idea seems to be that the restoration of the ACPI NVS area > > should complement whatever has been preserved by the platform over the > > hibernation/resume cycle. > > > IMO, if S5 was entered on "powe off", there are two possible ways to go. > > Either ACPI is initialized by the boot kernel, in which case the image kernel > > should not touch things like _WAK and similar, just throw away whatever > > ACPI-related state it got from the image and try to rebuild the ACPI-related > > data from scratch. Or the boot kernel doesn't touch ACPI and the image kernel > > initializes it in the same way as during a fresh boot (that might be difficult, > > though). > > Just an added data partial point. In the kexec case I have had not heard > anyone screaming to me that ACPI doesn't work after we switch kernels. You don't remove power from devices while doing that. > So I expect shutting down ACPI and restarting it should work reliably > and that is easy to test as that is already implemented with kexec. You can't program devices to generate wakeup events without ACPI, among other things. Anyway, I don't think you should focus on replacing the current hibernation code entirely so much. Thanks, Rafael