From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:38713) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QcCs5-0006Ar-Cy for qemu-devel@nongnu.org; Thu, 30 Jun 2011 04:45:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QcCs3-00078H-Q9 for qemu-devel@nongnu.org; Thu, 30 Jun 2011 04:45:13 -0400 Received: from mail-iw0-f173.google.com ([209.85.214.173]:58917) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QcCs3-00078A-Eh for qemu-devel@nongnu.org; Thu, 30 Jun 2011 04:45:11 -0400 Received: by iwn3 with SMTP id 3so1982829iwn.4 for ; Thu, 30 Jun 2011 01:45:10 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Wei Liu Date: Thu, 30 Jun 2011 16:44:40 +0800 Message-ID: Content-Type: text/plain; charset=UTF-8 Subject: Re: [Qemu-devel] Questions on DeviceState and Virtio infrastructure List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexander Graf Cc: Anthony Perard , "qemu-devel@nongnu.org" , Stefano Stabellini On Thu, Jun 30, 2011 at 4:31 PM, Alexander Graf wrote: > > On 29.06.2011, at 15:59, Wei Liu wrote: > >> Hi, QEMU folks >> >> I know that I might have a bad title for this post, but I just don't >> have better idea for the title. >> >> I'm developing virtio support for Xen pv guest, hoping to reuse the >> virtio infrastructure in qemu, i.e. I'm planning to use qemu as >> "virtio backend" for Xen pv. And qemu can be run as pv backend if >> proper "machine" option is given. >> >> Maybe you've known that Xen pv guest utilizes Xenbus/Xenstore to >> configure its paravirt devices. So I'm to configure virtio devices >> with Xenbus/Xenstore as well. But in nowdays XenDevice in qemu does >> not include a DeviceState. To my understanding, it is not connected to >> qemu's internal buses or whatever (correct me if I'm wrong, I'm >> relatively new to qemu). > > I'm not a huge fan of adding multiple different transports for virtio if we don't have to. IIRC Xen PV guests can do PCI device assignment, right? That means there is a PCI bus for them which we could reuse to run virtio-pci on. > > By then, you'd get all the virtio code for free and don't have to worry about maintaining yet another transport (which _is_ cumbersome) > Good point, I will check this. I thought that Xen pv pci assignment is only used for pci passthrough. But I will check the possibility to assign pv backend to guest. Stefano, how would you say about this? Wei.