From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753615Ab0FWPgo (ORCPT ); Wed, 23 Jun 2010 11:36:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:26647 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753250Ab0FWPgn (ORCPT ); Wed, 23 Jun 2010 11:36:43 -0400 Message-ID: <4C2229DB.6060706@redhat.com> Date: Wed, 23 Jun 2010 18:35:55 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-3.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: virtualization@lists.linux-foundation.org, Anthony Liguori , linux-pci@vger.kernel.org, Matt Carlson , linux-kernel@vger.kernel.org, Jesse Barnes , "Rafael J. Wysocki" , Kenji Kaneshige , Tejun Heo , "David S. Miller" , Bjorn Helgaas Subject: Re: [PATCH for-2.6.35] virtio-pci: disable msi at startup References: <20100610152252.GA3510@redhat.com> <4C22132F.4060307@redhat.com> <20100623135946.GA30526@redhat.com> <4C221871.6020509@redhat.com> <20100623144307.GB30526@redhat.com> <4C222508.2060804@redhat.com> <20100623152633.GC30526@redhat.com> In-Reply-To: <20100623152633.GC30526@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/23/2010 06:26 PM, Michael S. Tsirkin wrote: > > >>> >>> >>>>>> Shouldn't a reset be equivalent to power cycling? >>>>>> >>>>>> >>>>>> >>>>> If we did this, driver would need to restore registers >>>>> such as BAR etc. >>>>> >>>>> >>>>> >>>> We could save/restore the registers we care about. >>>> >>>> >>> It seems easier to clear registers we care about. >>> >> We know the registers we care about, we don't know the ones we don't. >> > If/when we use more registers, we can update driver to clear them on start. > The kdump kernel may not load drivers for those extra devices. >> I'm talking about FLRing all cards, not just those you want to use. >> > reset using FLR/PM is complex because of the need to save/restore > config space. Doing this on a crashing kernel sounds scary. > Well, you only need to save/restore for the devices you use. The rest you reset and forget. I don't really see why copying some config space is crazy. >>> It's also too late >>> now: changing behaviour will break old drivers. >>> >>> >> Why? the FLR is triggered by the guest kernel, so all drivers will be >> aware it was FLRed. >> > Not for FLR. Too late to reset on PA write. > > What's PA write? -- error compiling committee.c: too many arguments to function