On Mon, Aug 09, 2021 at 09:51:49AM +0000, Parav Pandit wrote: > > From: Michael S. Tsirkin <mst@xxxxxxxxxx> > > Sent: Monday, August 9, 2021 3:10 PM > > > > On Fri, Aug 06, 2021 at 08:55:56AM +0000, Parav Pandit wrote: > > > > > > > > > > > > > > The point is to try and not reinvent a dedicated vpda interface > > > > where a generic one exits. > > > > E.g. for phy things such as mac speed etc, I think most people are > > > > using ethtool things right? > > > > > > As you know vdpa is the backend device for the front-end netdevice > > accessed by the ethtool. > > > vdpa management tool here is composing the vdpa device. > > > > > > 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? > > > > > > I must be misunderstanding your comment about ethtool. > > > Can you please explain? > > > > > > I am basically saying that we probably want to be able to change MAC of a > > VDPA device on the host without desroying and recreating the device as long > > as it's not in use. > Ok. I understood your comment now. > Yes, this was the objective which is why they are present as independent config knob. > Jason was suggesting to have them as creation only knobs, which requires recreate. > > I don't have strong opinion for either method. > > Passing them at creation time is simpler for user. > If user needs the ability to modify and reuse same device with different config, extending such support in future like this patch should possible. > > So there are two questions to close. > 1. Can we start with config params at vdpa device creation time? I'm not sure whether we need both but I'd like to see a full API and I think we all agree host wants ability to tweak mac after device creation even if guest is not allowed to change mac, right? > 2. Is it ok to have these config params as individual fields at netlink U->K UAPI level? > This is the method proposed in this patch series. > (Similar to incrementally growing vxlan ip link command). > > Or > They should be packed in a structure between U-> K and deal with typecasting based on size and more? > (Jason's input). I'm inclined to say vxlan is closer to a model to follow. -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
