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    SubjectRe: [PATCH v10 0/7] PCI: Linux kernel SR-IOV support
    Yang, Sheng wrote:
    >>> Patches 2 and 3 of the patchset that enables SR/IOV in kvm [1] suggest
    >>> that at the config space is only partially implemented.
    >>>
    >>> [1] http://thread.gmane.org/gmane.comp.emulators.kvm.devel/29034
    >>>
    >> Hi Avi
    >>
    >> For kernel side, patch 2 is not necessary. Because kernel would read
    >> VID/DID directly from pci_dev rather than configuration space, which have
    >> been set properly already.
    >>
    >> And very sorry, for the patch 3. We haven't known exactly what's happened.
    >> I think the problem is caused by guest driver, but didn't confirm(and I
    >> have some misunderstandings with ZhaoYu for I thought we are agree on the
    >> reason, but after confirm with him, he didn't agree). I am doing more
    >> investigations to find the real cause.
    >>
    >
    > Found the reason of patch 3.
    >
    > After insert guest driver module(vf driver), the driver would do a RMW to the
    > command register to enable Bus Master bit(bit 2). And before that, MMIO bit
    > have been set in the register. But without the patch 3, guest driver won't see
    > the MMIO bit(bit 1), then just set 0x4 to the command register, with the side
    > effect to unmap MMIO in QEmu. So patch 3 is needed(and what I thought before
    > is right).
    >
    > Unset the bit only affect the QEmu, which would unmap the mapping for MMIO.
    > Kernel side don't need this, so it's OK.
    >

    Thanks for the explanations!

    --
    error compiling committee.c: too many arguments to function



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