Re: [virtio-dev] [pci PATCH v7 2/5] virtio_pci: Add support for unmanaged SR-IOV on virtio_pci devices

From: Rustad, Mark D
Date: Tue Apr 03 2018 - 15:18:33 EST

On Apr 3, 2018, at 11:27 AM, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:

I'm not sure why you would need a feature bit. The capability is
controlled via PCI configuration space. If it is present the device
has the capability. If it is not then it does not.

Basically if the PCI configuration space is not present then the sysfs
entries will not be spawned and nothing will attempt to use this

- ALex

It's about compability with older guests which ignore the

The feature is thus helpful so host knows whether guest supports VFs.

This is not about a guest creating its own VFs. This is about a host PF that happens to have a virtio interface to be able to create virtio VFs that can be assigned to guests. Nothing changes at all from a guest perspective. Or maybe I am not understanding what you mean by "whether guest supports VFs".

Mark Rustad, Networking Division, Intel Corporation

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