Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261414AbVDZJkb (ORCPT ); Tue, 26 Apr 2005 05:40:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261436AbVDZJka (ORCPT ); Tue, 26 Apr 2005 05:40:30 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:52368 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S261414AbVDZJkG (ORCPT ); Tue, 26 Apr 2005 05:40:06 -0400 Date: Tue, 26 Apr 2005 11:39:39 +0200 From: Pavel Machek To: Dave Jones , Andrew Morton , Alan Stern , alexn@dsv.su.se, greg@kroah.com, gud@eth.net, linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, jgarzik@pobox.com, cramerj@intel.com, linux-usb-devel@lists.sourceforge.net Subject: Re: [PATCH] PCI: Add pci shutdown ability Message-ID: <20050426093939.GC4175@elf.ucw.cz> References: <1114458325.983.17.camel@localhost.localdomain> <20050425145831.48f27edb.akpm@osdl.org> <20050425221326.GC15366@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050425221326.GC15366@redhat.com> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.6+20040907i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2034 Lines: 43 On Po 25-04-05 18:13:27, Dave Jones wrote: > On Mon, Apr 25, 2005 at 02:58:31PM -0700, Andrew Morton wrote: > > Alan Stern wrote: > > > > > > On Mon, 25 Apr 2005, Alexander Nyberg wrote: > > > > > > > Not sure what you mean by "make kexec work nicer" but if it is because > > > > some devices don't work after a kexec I have some objections. > > > > > > That was indeed the reason, at least in my case. The newly-rebooted > > > kernel doesn't work too well when there are active devices, with no driver > > > loaded, doing DMA and issuing IRQs because they were never shut down. > > > > I have vague memories of this being discussed at some length last year. > > Nothing comprehensive came of it, except that perhaps the kdump code should > > spin with irqs off for a couple of seconds so the DMA and IRQs stop. > > > > (Ongoing DMA is not a problem actually, because the kdump kernel won't be > > using that memory anyway) > > Actually, some cpufreq drivers *should* do their speed transitions with > all PCI mastering disabled. The lack of any infrastructure to quiesce drivers > and prevent new DMA transactions from occuring whilst the transition occurs > means that currently.. we don't. So +1 for any driver model work that > may lead to something we can use here. Well, you can do "half suspend to ram; change your frequency; half resume" today, and it should work, but I do not think you'll like the speed. In a ideal world, calling device_suspend(PMSG_FREEZE) gets you exactly that, and we'll do our best to make it fast enough. OTOH it *needs* to switch consoles to text one (because X may be running DMA, right?); I do not think you'll like that one. Pavel -- Boycott Kodak -- for their patent abuse against Java. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/