From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [RFC PATCH] vfio: VFIO PCI driver for Qemu Date: Thu, 26 Jul 2012 12:40:20 +0300 Message-ID: <50111084.1080700@redhat.com> References: <20120725165948.17260.82862.stgit@bling.home> <50104973.3090302@redhat.com> <1343246026.2229.374.camel@bling.home> <50110163.30209@redhat.com> <50110DC3.7000708@01019freenet.de> 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: Andreas Hartmann Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53289 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751758Ab2GZJkd (ORCPT ); Thu, 26 Jul 2012 05:40:33 -0400 In-Reply-To: <50110DC3.7000708@01019freenet.de> Sender: kvm-owner@vger.kernel.org List-ID: On 07/26/2012 12:28 PM, Andreas Hartmann wrote: > 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! Do we know why it doesn't work? > Please let the users decide them self which tool to use! -device pci-assign,kernel-driver=vfio (it will be the default in any case) -- error compiling committee.c: too many arguments to function