From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Hartmann Subject: Re: [RFC PATCH] vfio: VFIO PCI driver for Qemu Date: Thu, 26 Jul 2012 11:28:35 +0200 Message-ID: <50110DC3.7000708@01019freenet.de> References: <20120725165948.17260.82862.stgit@bling.home> <50104973.3090302@redhat.com> <1343246026.2229.374.camel@bling.home> <50110163.30209@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Alex Williamson , kvm@vger.kernel.org, aik@ozlabs.ru, benh@kernel.crashing.org To: Avi Kivity Return-path: Received: from mout6.freenet.de ([195.4.92.96]:38333 "EHLO mout6.freenet.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750766Ab2GZJbW (ORCPT ); Thu, 26 Jul 2012 05:31:22 -0400 In-Reply-To: <50110163.30209@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity wrote: > On 07/25/2012 10:53 PM, Alex Williamson wrote: >> On Wed, 2012-07-25 at 22:30 +0300, Avi Kivity wrote: >>> On 07/25/2012 08:03 PM, Alex Williamson wrote: >>>> This adds PCI based device assignment to Qemu using the Linux VFIO >>>> userspace driver interface. After setting up VFIO device access, >>>> devices can be added to Qemu guests using the vfio-pci device >>>> option: >>>> >>>> -device vfio-pci,host=1:10.1,id=net0 >>>> >>>> >>> >>> Let's use the same syntax as for kvm device assignment. Then we can >>> fall back on kvm when vfio is not available. We can also have an >>> optional parameter kernel-driver to explicitly select vfio or kvm. >> >> This seems confusing to me, pci-assign already has options like >> prefer_msi, share_intx, and configfd that vfio doesn't. I'm sure vfio >> will eventually get options that pci-assign won't have. How is a user >> supposed to figure out what options are actually available from -device >> pci-assign,? > > Read the documentation. > >> Isn't this the same as asking to drop all model specific >> devices and just use -device net,model=e1000... hey, we've been there >> before ;) Thanks, > > It's not. e1000 is a guest visible feature. vfio and kvm assignment do > exactly the same thing, as far as the guest is concerned, The big difference between vfio and old kvm assignment is: vfio does work for PCI here, kvm doesn't! Please let the users decide them self which tool to use! Sorry, kind regards, Andreas