Re: [PATCH 5/7] I/OAT: Add support for MSI and MSI-X

[Roland Dreier]

 > In a case where you have a device that which supports MSI-X (multiple
 > interrupts) but the device in default is in MSI mode, ie some
 > configuration change is needed on the device. In such a case, how
 > would one handle between MSI-X and MSI ?
 > 
 > ie the device initially doesn't support MSI-X

I don't understand the question really.  Does the PCI spec even allow
a device to be in MSI mode by default?  Surely the OS must initialize
the address/message before the device can generate an MSI?

What device do you have in mind?  I guess the interesting case is a
PCIe device that supports MSI and MSI-X but not legacy interrupts.
However I would assume such a device would come up with both MSI and
MSI-X disabled.

 - R.
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