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    SubjectRe: [GIT PULL] AlacrityVM guest drivers for 2.6.33
    On Tue, 22 Dec 2009, Gregory Haskins wrote:

    > On 12/22/09 1:53 PM, Avi Kivity wrote:
    > > I asked why the irqfd/ioeventfd mechanisms are insufficient, and you did not reply.
    > >
    >
    > BTW: the ioeventfd issue just fell through the cracks, so sorry about
    > that. Note that I have no specific issue with irqfd ever since the
    > lockless IRQ injection code was added.
    >
    > ioeventfd turned out to be suboptimal for me in the fast path for two
    > reasons:
    >
    > 1) the underlying eventfd is called in atomic context. I had posted
    > patches to Davide to address that limitation, but I believe he rejected
    > them on the grounds that they are only relevant to KVM.

    I thought we addressed this already, in the few hundreds of email we
    exchanged back then :)



    > 2) it cannot retain the data field passed in the PIO. I wanted to have
    > one vector that could tell me what value was written, and this cannot be
    > expressed in ioeventfd.

    Like might have hinted in his reply, couldn't you add data support to the
    ioeventfd bits in KVM, instead of leaking them into mainline eventfd?



    - Davide




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