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    SubjectRe: [PATCH RFC] pass write value to in_range pointers
    On 06/22/2009 07:08 PM, Michael S. Tsirkin wrote:
    > On Mon, Jun 22, 2009 at 11:45:00AM -0400, Gregory Haskins wrote:
    >
    >> Michael S. Tsirkin wrote:
    >>
    >>> It seems that a lot of complexity and trickiness with iosignalfd is
    >>> handling the group/item relationship, which comes about because kvm does
    >>> not currently let a device on the bus claim a write transaction based on the
    >>> value written. This could be greatly simplified if the value written
    >>> was passed to the in_range check for write operation. We could then
    >>> simply make each kvm_iosignalfd a device on the bus.
    >>>
    >>> What does everyone think of the following lightly tested patch?
    >>>
    >>>
    >> Hi Michael,
    >> Its interesting, but I am not convinced its necessary. We created the
    >> group/item layout because iosignalfds are unique in that they are
    >> probably the only IO device that wants to do some kind of address
    >> aliasing.
    >>
    >
    > We actually already have aliasing: is_write flag is used for this
    > purpose. Actually, it's possible to remove is_write by passing
    > a null pointer in write_val for reads. I like this a bit less as
    > the code generated is less compact ... Avi, what do you think?
    >

    Greg, won't Michael's patch eliminate a big chunk from your iosignalfd
    patches? Seems like a win to me.

    > One is enough :)
    > Seriously, do you see that this saves you all of RCU, linked lists and
    > counters? You don't need to keep track of iofds, you don't need to
    > implement your own lookup logic - you just use the kvm device
    > and that's it.
    >
    >

    Yup.

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



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