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SubjectRe: [PATCH 1/2] msi: Invert the sense of the MSI enables.
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 > > In addition to PCI INTx compatible interrupt emulation, PCI Express
> > requires support of MSI or MSI-X or both.
> Which suggests that INTx support is required.
>
> I do not find any wording that suggest the opposite.
> I do see it stated that it is intended to EOL support for INTx at
> some point.
>
> Where did you see it mentioned that INTx was optional?

I don't see any requirement that a device that generates MSI
interrupts must also be able to signal the same interrupts via INTx.
The spec explicitly says:

"All PCI Express device Functions that are capable of generating
interrupts must support MSI or MSI-X or both."

but there is no corresponding explicit requirement that legacy INTx
mode be supported, so it certainly seems permitted for a device not to
generate INTx interrupts. In fact as you alluded to, the spec says,

"The legacy INTx emulation mechanism may be deprecated in a future
version of this specification."

and I wouldn't think the intention would be for one version of the
spec to *require* something that is planned on being deprecated later.

And the Pathscale guys were pretty confident that their device was
compliant with the PCIe spec.

- R.
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