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    SubjectRe: PCIE
    Roland Dreier wrote:
    > I have a hard time imagining a PCI host bus controller that converts
    > MSI interrupts back to wire interrupts that go to pins on the CPU.
    > For one thing it would be hard to maintain the guarantee that
    > MSI interrupts can't pass DMAs. And it would be an absolutely silly
    > architecture too.

    Well, on pretty much all CPUs interrupts sooner or later are combined to
    an interrupt signal (not necessarily an external pin) on the CPU
    indicating that an interrupt has happened. On many CPUs demultiplex is
    then done in software.

    As I said, I have seen at least one architecture where MSIs are treated
    as nothing other than another PCI interrupt -- you get five status bits
    from the PCI unit -- INTA, INTB, INTC, INTD, MSI. Needless to say, I
    didn't bother enabling MSI on that platform. Even if it had worked
    correctly, which I kind of doubt, it would probably have been a net loss.

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      Last update: 2007-05-28 07:27    [W:0.019 / U:4.744 seconds]
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