Re: [PATCH v3 2/3] uio_pci_generic: add MSI/MSI-X support

From: Michael S. Tsirkin
Date: Tue Oct 06 2015 - 10:56:19 EST


On Tue, Oct 06, 2015 at 05:43:50PM +0300, Vlad Zolotarov wrote:
> The only "like VFIO" behavior we implement here is binding the MSI-X
> interrupt notification to eventfd descriptor.

There will be more if you add some basic memory protections.

Besides, that's not true.
Your patch queries MSI capability, sets # of vectors.
You even hinted you want to add BAR mapping down the road.

VFIO does all of that.

> This doesn't justifies the
> hassle of implementing IOMMU-less VFIO mode.

This applies to both VFIO and UIO really. I'm not sure the hassle of
maintaining this functionality in tree is justified. It remains to be
seen whether there are any users that won't taint the kernel.
Apparently not in the current form of the patch, but who knows.

--
MST
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