Multiple vector domain support

Hi,

I'm attaching the series of patches for handling huge number of interrtupt sources. This patch is to increase vector spaces by separating processors into some domains. This idea is the same as "per node IDT" posted by Zwane Mwaikambo at:

    http://marc.theaimsgroup.com/?l=linux-kernel&m2103551401596&w=2

The ia64 linux already have vector sharing to handle huge number of level-triggered interrupt sources via I/O SAPIC, but I think we also need per domain vector approach because:

o Supporting vector shairng for edge-triggered interrupts is difficult (or impossible)

o Vector domain approach has better performance than vector sharing

o Need to support MSI based interrupts

This series of patches is still under development, and has following TBD items.

o How to create vector domains

Need to consider how to create vector domains(per CPU?, per node? or others...)

o MSI support

Attached patch only supports vector domain for I/O SAPIC interrupts. We need to consider how to support vector domain for MSI interrupts.

o /proc interface

o How to handle CPU hotplug

o and so on..

Any comments and questions are welcomed.

Thanks,
Kenji Kaneshige