From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Borntraeger Subject: Re: [PATCH 3/4] s390/kvm: Add a channel I/O based virtio transport driver. Date: Wed, 15 Aug 2012 09:48:44 +0200 Message-ID: <502B545C.8000904@de.ibm.com> References: <1344351168-2568-1-git-send-email-cornelia.huck@de.ibm.com> <1344351168-2568-4-git-send-email-cornelia.huck@de.ibm.com> <87fw7ps0x4.fsf@codemonkey.ws> <878vdgr4v2.fsf@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <878vdgr4v2.fsf@rustcorp.com.au> Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: Rusty Russell Cc: Anthony Liguori , Cornelia Huck , KVM , linux-s390 , qemu-devel , Avi Kivity , Marcelo Tosatti , Carsten Otte , Alexander Graf , Heiko Carstens , Martin Schwidefsky , Sebastian Ott List-ID: >> Have you written an appendix for the virtio specification for >> virtio-ccw? I think it would be good to include in this series for the >> purposes of review. > > Might be nice, but don't get fancy about it. Text will be fine and I > can cut & paste it in once it's finalized. There was a patch against the virtio spec in the patch series. Did it not make it to you? But Anthony is right, the spec is important, because the two main things that we need to get right are the 2 interfaces guest<->host and userspace(qemu)<->kvm. Everything else is not an ABI and can be fixed later on if necessary. Regarding the guest<->host interface a lot of things are mandated by the channel-IO architecture. We have also reserved some IDs for virtio (control unit type 0x3832, channel path type 0x32 and channel subsystem id 0xfe) so we just have to focus on the virtio part (thanks Rusty for the good feedback already). Regarding the qemu<->kvm interface it is important to have an interface that - allows us to be architectural compliant - which is fast - which must not prevent features like vhost - which allows to implement live migration - ...? Christian From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:37829) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T1YLS-0003No-Km for qemu-devel@nongnu.org; Wed, 15 Aug 2012 03:48:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T1YLR-0001eJ-H7 for qemu-devel@nongnu.org; Wed, 15 Aug 2012 03:48:50 -0400 Received: from e06smtp10.uk.ibm.com ([195.75.94.106]:37941) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T1YLR-0001e2-8j for qemu-devel@nongnu.org; Wed, 15 Aug 2012 03:48:49 -0400 Received: from /spool/local by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 15 Aug 2012 08:48:47 +0100 Received: from d06av10.portsmouth.uk.ibm.com (d06av10.portsmouth.uk.ibm.com [9.149.37.251]) by b06cxnps4076.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q7F7md2e14811302 for ; Wed, 15 Aug 2012 07:48:39 GMT Received: from d06av10.portsmouth.uk.ibm.com (loopback [127.0.0.1]) by d06av10.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q7F7JrKo027632 for ; Wed, 15 Aug 2012 03:19:53 -0400 Message-ID: <502B545C.8000904@de.ibm.com> Date: Wed, 15 Aug 2012 09:48:44 +0200 From: Christian Borntraeger MIME-Version: 1.0 References: <1344351168-2568-1-git-send-email-cornelia.huck@de.ibm.com> <1344351168-2568-4-git-send-email-cornelia.huck@de.ibm.com> <87fw7ps0x4.fsf@codemonkey.ws> <878vdgr4v2.fsf@rustcorp.com.au> In-Reply-To: <878vdgr4v2.fsf@rustcorp.com.au> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 3/4] s390/kvm: Add a channel I/O based virtio transport driver. List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Rusty Russell Cc: linux-s390 , Anthony Liguori , KVM , Carsten Otte , Sebastian Ott , Marcelo Tosatti , Heiko Carstens , qemu-devel , Alexander Graf , Martin Schwidefsky , Avi Kivity , Cornelia Huck >> Have you written an appendix for the virtio specification for >> virtio-ccw? I think it would be good to include in this series for the >> purposes of review. > > Might be nice, but don't get fancy about it. Text will be fine and I > can cut & paste it in once it's finalized. There was a patch against the virtio spec in the patch series. Did it not make it to you? But Anthony is right, the spec is important, because the two main things that we need to get right are the 2 interfaces guest<->host and userspace(qemu)<->kvm. Everything else is not an ABI and can be fixed later on if necessary. Regarding the guest<->host interface a lot of things are mandated by the channel-IO architecture. We have also reserved some IDs for virtio (control unit type 0x3832, channel path type 0x32 and channel subsystem id 0xfe) so we just have to focus on the virtio part (thanks Rusty for the good feedback already). Regarding the qemu<->kvm interface it is important to have an interface that - allows us to be architectural compliant - which is fast - which must not prevent features like vhost - which allows to implement live migration - ...? Christian