From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754112AbbDNIZF (ORCPT ); Tue, 14 Apr 2015 04:25:05 -0400 Received: from e06smtp15.uk.ibm.com ([195.75.94.111]:47586 "EHLO e06smtp15.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753978AbbDNIYu (ORCPT ); Tue, 14 Apr 2015 04:24:50 -0400 Date: Tue, 14 Apr 2015 10:24:38 +0200 From: Cornelia Huck To: Rusty Russell Cc: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, Pawel Moll , virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v3 0/6] virtio_balloon: virtio 1 support Message-ID: <20150414102438.11d12347.cornelia.huck@de.ibm.com> In-Reply-To: <87h9sjtsvb.fsf@rustcorp.com.au> References: <1427884468-23930-1-git-send-email-mst@redhat.com> <20150412170141-mutt-send-email-mst@redhat.com> <87h9sjtsvb.fsf@rustcorp.com.au> Organization: IBM Deutschland Research & Development GmbH Vorsitzende des Aufsichtsrats: Martina Koederitz =?UTF-8?B?R2VzY2jDpGZ0c2bDvGhydW5nOg==?= Dirk Wittkopp Sitz der Gesellschaft: =?UTF-8?B?QsO2Ymxpbmdlbg==?= Registergericht: Amtsgericht Stuttgart, HRB 243294 X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15041408-0021-0000-0000-00000390E53A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 14 Apr 2015 10:42:56 +0930 Rusty Russell wrote: > "Michael S. Tsirkin" writes: > > On Wed, Apr 01, 2015 at 02:57:35PM +0200, Michael S. Tsirkin wrote: > >> Virtio 1.0 doesn't include a modern balloon device. At some point we'll likely > >> define an incompatible interface with a different ID and different > >> semantics. But for now, it's not a big effort to support a transitional > >> balloon device: this has the advantage of supporting existing drivers, > >> transparently, as well as transports that don't allow mixing virtio 0 and > >> virtio 1 devices. And balloon is an easy device to test, so it's also useful > >> for people to test virtio core handling of transitional devices. > >> > >> The only interface issue is with the stats buffer, which has misaligned > >> fields. We could leave it as is, but this sets a bad precedent that > >> others might copy by mistake. > >> > >> As we need to change stats code to do byteswaps for virtio 1.0, it seems easy > >> to fix by prepending a 6 byte reserved field. I also had to change config > >> structure field types from __le32 to __u32 to match other devices. This means > >> we need a couple of __force tags for legacy path but that seems minor. > > > > Rusty, what are your thoughts here? > > How about merging this for 4.1? > > I disagree with making any changes, other than allowing it to be used > with VIRTIO_F_VERSION_1. > > However it doesn't seem to bother anyone else, so I've applied it for > 4.1. I'm still not really convinced about the stats change either, FWIW. Still time to reconsider? And should we perhaps wait with merging until the spec change allowing version 1 has been accepted? From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH v3 0/6] virtio_balloon: virtio 1 support Date: Tue, 14 Apr 2015 10:24:38 +0200 Message-ID: <20150414102438.11d12347.cornelia.huck@de.ibm.com> References: <1427884468-23930-1-git-send-email-mst@redhat.com> <20150412170141-mutt-send-email-mst@redhat.com> <87h9sjtsvb.fsf@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87h9sjtsvb.fsf@rustcorp.com.au> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Rusty Russell Cc: virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Pawel Moll , "Michael S. Tsirkin" List-Id: virtualization@lists.linuxfoundation.org On Tue, 14 Apr 2015 10:42:56 +0930 Rusty Russell wrote: > "Michael S. Tsirkin" writes: > > On Wed, Apr 01, 2015 at 02:57:35PM +0200, Michael S. Tsirkin wrote: > >> Virtio 1.0 doesn't include a modern balloon device. At some point we'll likely > >> define an incompatible interface with a different ID and different > >> semantics. But for now, it's not a big effort to support a transitional > >> balloon device: this has the advantage of supporting existing drivers, > >> transparently, as well as transports that don't allow mixing virtio 0 and > >> virtio 1 devices. And balloon is an easy device to test, so it's also useful > >> for people to test virtio core handling of transitional devices. > >> > >> The only interface issue is with the stats buffer, which has misaligned > >> fields. We could leave it as is, but this sets a bad precedent that > >> others might copy by mistake. > >> > >> As we need to change stats code to do byteswaps for virtio 1.0, it seems easy > >> to fix by prepending a 6 byte reserved field. I also had to change config > >> structure field types from __le32 to __u32 to match other devices. This means > >> we need a couple of __force tags for legacy path but that seems minor. > > > > Rusty, what are your thoughts here? > > How about merging this for 4.1? > > I disagree with making any changes, other than allowing it to be used > with VIRTIO_F_VERSION_1. > > However it doesn't seem to bother anyone else, so I've applied it for > 4.1. I'm still not really convinced about the stats change either, FWIW. Still time to reconsider? And should we perhaps wait with merging until the spec change allowing version 1 has been accepted?