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    SubjectRe: [PATCHv4] uio: add generic driver for PCI 2.3 devices
    On Mon, Jul 20, 2009 at 10:17:02AM -0700, Jesse Barnes wrote:
    > On Wed, 15 Jul 2009 23:39:11 +0200
    > "Hans J. Koch" <hjk@linutronix.de> 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.

    Yes, and Greg seems satisfied :). See 20090716181919.GB27811@suse.de.
    Chris Wright (author of pci-stub that was mentioned) also acked the
    patch.

    > --
    > Jesse Barnes, Intel Open Source Technology Center


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