Re: [PATCH 0/1] uio_pci_generic: extensions to allow access for non-privilegedprocesses

From: Avi Kivity
Date: Fri Apr 02 2010 - 02:44:00 EST

On 04/01/2010 10:24 PM, Tom Lyon wrote:

But there are multiple msi-x interrupts, how do you know which one
You don't. This would suck for KVM, I guess, but we'd need major rework of the
generic UIO stuff to have a separate event channel for each MSI-X.

Doesn't it suck for non-kvm in the same way? Multiple vectors are there for a reason. For example, if you have a multiqueue NIC, you'd have to process all queues instead of just the one that triggered.

For my purposes, collapsing all the MSI-Xs into one MSI-look-alike is fine,
because I'd be using MSI anyways if I could. The weird Intel 82599 VF only
supports MSI-X.

So one big question is - do we expand the whole UIO framework for KVM
requirements, or do we split off either KVM or non-VM into a separate driver?
Hans or Greg - care to opine?

Currently kvm does device assignment with its own code, I'd like to unify it with uio, not split it off.

Separate notifications for msi-x interrupts are just as useful for uio as they are for kvm.

Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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