From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52835) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c6jF4-0003WG-B9 for qemu-devel@nongnu.org; Tue, 15 Nov 2016 14:18:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c6jF1-0003j5-7V for qemu-devel@nongnu.org; Tue, 15 Nov 2016 14:18:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:52670) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c6jF0-0003i5-Vf for qemu-devel@nongnu.org; Tue, 15 Nov 2016 14:17:59 -0500 Date: Tue, 15 Nov 2016 21:17:56 +0200 From: "Michael S. Tsirkin" Message-ID: <20161115211703-mutt-send-email-mst@kernel.org> References: <20161115134629.23161-1-pbonzini@redhat.com> <20161115134629.23161-4-pbonzini@redhat.com> <20161115172336-mutt-send-email-mst@kernel.org> <9f83bd81-b077-4234-d2e2-1ffea4d35168@redhat.com> <20161115173913-mutt-send-email-mst@kernel.org> <61184b66-b6dc-b766-a629-537537a92776@redhat.com> <20161115184631-mutt-send-email-mst@kernel.org> <20161115104815.61c1f539@t450s.home> <20161115195346-mutt-send-email-mst@kernel.org> <20161115112155.688f0bf2@t450s.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161115112155.688f0bf2@t450s.home> Subject: Re: [Qemu-devel] [PATCH 3/3] virtio: set ISR on dataplane notifications List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: Paolo Bonzini , qemu-devel@nongnu.org, borntraeger@de.ibm.com, felipe@nutanix.com On Tue, Nov 15, 2016 at 11:21:55AM -0700, Alex Williamson wrote: > On Tue, 15 Nov 2016 19:58:52 +0200 > "Michael S. Tsirkin" wrote: > > > On Tue, Nov 15, 2016 at 10:48:15AM -0700, Alex Williamson wrote: > > > On Tue, 15 Nov 2016 19:38:30 +0200 > > > "Michael S. Tsirkin" wrote: > > > > > > > On Tue, Nov 15, 2016 at 05:22:49PM +0100, Paolo Bonzini wrote: > > > > > > > > > > > > > > > On 15/11/2016 16:44, Michael S. Tsirkin wrote: > > > > > > True. We could drop it from non-data plane, it's just that we never had > > > > > > a reason to. vhost in kernel does not set ISR in MSI mode, either. > > > > > > > > > > Yeah, I suspected that. But dropping it from non-dataplane would break > > > > > Windows hibernation and crashdump, just like it did for Alex. > > > > > > > > I guess it's just a question of updating the drivers, > > > > isn't it? To me, hibernation/crashdump doesn't sound important > > > > enough to warrant work-arounds, but if you feel otherwise, > > > > I'm fine with doing this work-around for dataplane. > > > > > > The fact that Windows is trying to do some sort of hibernation is not > > > visible to the user, I'm simply trying to shutdown the VM. That's > > > rather important on my scale of functionality. If we have drivers in > > > the wild doing this, does it matter what's in the spec? > > > > It matters that latest drivers are already OK. "Update drivers" > > has been the advice for any kind of windows problem for years. > > > > > Smells like a > > > regression from an end user perspective. Thanks, > > > > > > Alex > > > > This exposes a driver bug, yes. The right fix is easy to point > > out, whether we want a work-around I'm not sure - I understand that > > you feel strongly that we do, is that right? OK, just let's document > > what's going on and which versions are affected. > > I don't mind updating my drivers, I'm just guessing that the average > user doesn't know what virtio driver version they're running, doesn't > read release notes, and will be at least slightly annoyed by this > behavior that looks and smells like a regression from v2.7. If it > hit me, then there are probably others affected as well. It's up to you > to weigh maintaining not-entirely-spec-complaint behavior vs user angst. > Thanks, > > Alex I think I'll merge the work-around if it's better documented. If you think it should go in, can you provide your tested-by tag? -- MST