From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753271AbXLHXxT (ORCPT ); Sat, 8 Dec 2007 18:53:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752990AbXLHXxM (ORCPT ); Sat, 8 Dec 2007 18:53:12 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:48340 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752875AbXLHXxL (ORCPT ); Sat, 8 Dec 2007 18:53:11 -0500 Date: Sun, 9 Dec 2007 00:53:44 +0100 From: Pavel Machek To: "Huang, Ying" Cc: "Eric W. Biederman" , nigel@nigel.suspend2.net, "Rafael J. Wysocki" , Andrew Morton , Jeremy Maitin-Shepard , linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, Kexec Mailing List Subject: Re: [PATCH 1/4 -mm] kexec based hibernation -v7 : kexec jump Message-ID: <20071208235344.GA17005@elf.ucw.cz> References: <1197042810.24045.61.camel@caritas-dev.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1197042810.24045.61.camel@caritas-dev.intel.com> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! > This patch implements the functionality of jumping between the kexeced > kernel and the original kernel. > > To support jumping between two kernels, before jumping to (executing) > the new kernel and jumping back to the original kernel, the devices > are put into quiescent state, and the state of devices and CPU is > saved. After jumping back from kexeced kernel and jumping to the new > kernel, the state of devices and CPU are restored accordingly. The > devices/CPU state save/restore code of software suspend is called to > implement corresponding function. > > To support jumping without reserving memory. One shadow backup page > (source page) is allocated for each page used by new (kexeced) kernel > (destination page). When do kexec_load, the image of new kernel is > loaded into source pages, and before executing, the destination pages > and the source pages are swapped, so the contents of destination pages > are backupped. Before jumping to the new (kexeced) kernel and after > jumping back to the original kernel, the destination pages and the > source pages are swapped too. > > A jump back protocol for kexec is defined and documented. It is an > extension to ordinary function calling protocol. So, the facility > provided by this patch can be used to call ordinary C function in real > mode. > > A set of flags for sys_kexec_load are added to control which state are > saved/restored before/after real mode code executing. For example, you > can specify the device state and FPU state are saved/restored > before/after real mode code executing. > > The states (exclude CPU state) save/restore code can be overridden > based on the "command" parameter of kexec jump. Because more states > need to be saved/restored by hibernating/resuming. > > Signed-off-by: Huang Ying I'm not kexec hacker... but maybe this is in good enough state to be merged? It is useful on its own: kexec jump and back means we can dump system then continue running, for example... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html