Hi Jason,

From: Jason Wang <jasowang@redhat.com>
Sent: Monday, August 9, 2021 8:38 AM

quoted

For example creator (hypervisor) of the vdpa devices knows that a
guest VM is given 4 vcpus, So hypervisor creates a vdpa devices with
config space layout as, max_virtqueue_pairs = 4.
And the MAC address chosen by hypervisor in mac[6].

Guest VM ethtool can still chose to use less number of channels.

Typically,
ethtool is for guest VM.
vdpa device is in hypevisor.

How can hypervisor compose a vdpa device without any tool?
How can it tell ethtool, what is supported and what are the defaults?

Reread the cover letter:

"

This patchset enables users to set the mac address and mtu of the vdpa
device once the device is created.

"

It looks to me the mechanism that introduced in the series is not for
provisioning but for post-creation configuration?

quoted

I must be misunderstanding your comment about ethtool.
Can you please explain?

I guess the meaning is that, if the vDPA is assigned to guest, it's the
charge of guest to configure the MTU/MAC/RSS via the existing management
interface like ethtool/iproute2 netlink protocol. The control virtqueue
is designed for this.

But if it was used for provisioning, it looks like another topic which
should be done during the device creation.

We already discussed and agreed, that I should change these params as creation time params instead post-creation.
We were waiting for Michael to respond if he is ok with either 
(a) extendible individual param or 
(b) should prefer to see a typecast based structure blob coming through netlink.
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