Re: [PATCH 6/6] Add MSI support to XEN

[Neil Turton <nturton@solarflare.com>]

I tried the latest unstable tree on a NIC which supports both MSI and
MSI-X.  When the driver was configured to use MSI mode, everything
worked fine but when it was configured to use MSI-X, the call to
pci_enable_msix succeeded but the interrupt didn't work.  Have these
patches been seen to work on an MSI-X device?

In msix_capability_init (drivers/pci/msi-xen.c), there's a loop which
unmaps the old pirqs.  Shouldn't there be some similar code in
msi_capability_init?  I can't see any reason for the inconsistency
between the two functions.

Would it be possible to extend this code so that a PV backend driver
could map different MSI-X entries on a PCI device into different guests?
We already have frontend/backend drivers which allow multiple guests to
securely access the PCI memory of a single NIC and would like to extend
those drivers to map MSI-X interrupts directly to guests.  I
still don't understand enough about the new hypercalls to see how that
would work.

Cheers, Neil.