From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesse Barnes Subject: Re: [PATCHv4] uio: add generic driver for PCI 2.3 devices Date: Mon, 20 Jul 2009 10:17:02 -0700 Message-ID: <20090720101702.68fee1ab@jbarnes-g45> References: <20090715201340.GA12279@redhat.com> <20090715213909.GA3637@local> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: "Michael S. Tsirkin" , anthony@codemonkey.ws, avi@redhat.com, kvm@vger.kernel.org, chrisw@redhat.com, hjk@linutronix.de, gregkh@suse.de, linux-kernel@vger.kernel.org To: "Hans J. Koch" Return-path: In-Reply-To: <20090715213909.GA3637@local> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Wed, 15 Jul 2009 23:39:11 +0200 "Hans J. Koch" wrote: > On Wed, Jul 15, 2009 at 11:13:40PM +0300, Michael S. Tsirkin wrote: > > This adds a generic uio driver that can bind to any PCI device. > > First user will be virtualization where a qemu userspace process > > needs to give guest OS access to the device. > > > > Interrupts are handled using the Interrupt Disable bit in the PCI > > command register and Interrupt Status bit in the PCI status > > register. All devices compliant to PCI 2.3 (circa 2002) and all > > compliant PCI Express devices should support these bits. Driver > > detects this support, and won't bind to devices which do not > > support the Interrupt Disable Bit in the command register. > > > > It's expected that more features of interest to virtualization will > > be added to this driver in the future. Possibilities are: mmap for > > device resources, MSI/MSI-X, eventfd (to interface with kvm), iommu. > > Well, I'm not enough of a PCI expert to tell whether your 2.3-test > works or not (can it have side effects, e.g. trigger an interrupt > when you toggle that bit?). I've added Jesse Barnes to Cc: since you > modify a PCI core header file. If there are no objections from the > PCI people, I guess we can take this. pci_reg.h portion looks fine to me, and only supporting devices with the interrupt disable bit certainly simplifies things. There were some other questions on the thread though (like Greg's similar driver); not sure if you've answered those yet. -- Jesse Barnes, Intel Open Source Technology Center