From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: Re: [RFC] VirtFS support on Xen Date: Mon, 25 Jan 2016 15:13:45 +0000 Message-ID: <20160125151345.GC1943@citrix.com> References: <20160121102844.GP1691@citrix.com> <56A0B7E0.20606@citrix.com> <20160121105958.GR1691@citrix.com> <56A2084A.8010803@oracle.com> <20160122105035.GZ1691@citrix.com> <56A310B4.3080808@oracle.com> <20160123145030.GA9393@citrix.com> <393D2BE6-1E09-47BF-B50D-1B1E688A81FD@oracle.com> <20160125112915.GC1691@citrix.com> <56A6088E.2080803@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aNiq2-0006Fq-Oy for xen-devel@lists.xenproject.org; Mon, 25 Jan 2016 15:13:54 +0000 Content-Disposition: inline In-Reply-To: <56A6088E.2080803@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: David Vrabel Cc: Xen-devel , Wei Liu List-Id: xen-devel@lists.xenproject.org On Mon, Jan 25, 2016 at 11:35:42AM +0000, David Vrabel wrote: > On 25/01/16 11:29, Wei Liu wrote: > > > > That goes back to the old topic of how to make VirtIO work on Xen (PV in > > particular). It's not easy task by any means. > > This is a (very) useful thing to solve anyway so why not go down this > route? Particularly, since the latest discussion had reached a > conclusion about how to do this (white-listing virtio devices that need > to use the DMA API, if I remember correctly). > I thought about that before. The changes made by Andy doesn't make VirtIO work for PV guest automatically. To make it work for PV guest, we either need to make virtio-mmio / virtio-pci work for PV guests (is there a way to register QEMU as emulator for PV guests?) or develop virtio-xen transport for VirtIO. (I think virtio-xen makes more sense fwiw) Then inevitably we will get hit by questions with performance issues like [0] once we open the flood gate to allow all virtio devices to be used on Xen and claim it is "supported". If there is no clear plan to make VirtIO on Xen functional and performant by default I'm afraid it's not a good way forward at the moment. Wei. [0] <56701113.1080107@sinte.net> > David