From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH] VFIO driver: Non-privileged user level PCI drivers Date: Wed, 2 Jun 2010 11:42:01 +0200 Message-ID: <20100602094201.GC964@8bytes.org> References: <4C025999.7080706@redhat.com> <20100530124949.GI27611@redhat.com> <4C0261C1.9090204@redhat.com> <20100530130332.GM27611@redhat.com> <4C026497.8070901@redhat.com> <20100530145309.GO27611@redhat.com> <4C03A285.7060902@redhat.com> <20100531171007.GA6516@redhat.com> <4C04C085.1030107@redhat.com> <20100601095532.GA9178@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Tom Lyon , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, chrisw@sous-sol.org, hjk@linutronix.de, gregkh@suse.de, aafabbri@cisco.com, scofeldm@cisco.com To: "Michael S. Tsirkin" Return-path: Content-Disposition: inline In-Reply-To: <20100601095532.GA9178@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Tue, Jun 01, 2010 at 12:55:32PM +0300, Michael S. Tsirkin wrote: > There seems to be some misunderstanding. The userspace interface > proposed forces a separate domain per device and forces userspace to > repeat iommu programming for each device. We are better off sharing a > domain between devices and programming the iommu once. > > The natural way to do this is to have an iommu driver for programming > iommu. IMO a seperate iommu-userspace driver is a nightmare for a userspace interface. It is just too complicated to use. We can solve the problem of multiple devices-per-domain with an ioctl which allows binding one uio-device to the address-space on another. Thats much simpler. Joerg