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Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor |
Date: |
Wed, 3 Jan 2018 15:49:21 +0200 |
On Thu, Dec 28, 2017 at 10:53:54AM -0500, Jason Baron wrote:
>
>
> On 12/27/2017 04:43 PM, David Miller wrote:
> > From: Jason Baron <address@hidden>
> > Date: Fri, 22 Dec 2017 16:54:01 -0500
> >
> >> The ability to set speed and duplex for virtio_net in useful in various
> >> scenarios as described here:
> >>
> >> 16032be virtio_net: add ethtool support for set and get of settings
> >>
> >> However, it would be nice to be able to set this from the hypervisor,
> >> such that virtio_net doesn't require custom guest ethtool commands.
> >>
> >> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
> >> the hypervisor to export a linkspeed and duplex setting. The user can
> >> subsequently overwrite it later if desired via: 'ethtool -s'.
> >>
> >> Signed-off-by: Jason Baron <address@hidden>
> >> Cc: "Michael S. Tsirkin" <address@hidden>
> >> Cc: Jason Wang <address@hidden>
> >
> > Looks mostly fine to me but need some virtio_net reviewers on this one.
> >
> >> @@ -57,6 +57,8 @@
> >> * Steering */
> >> #define VIRTIO_NET_F_CTRL_MAC_ADDR 23 /* Set MAC address */
> >>
> >> +#define VIRTIO_NET_F_SPEED_DUPLEX 63 /* Host set linkspeed and
> >> duplex */
> >> +
> >
> > Why use a value so far away from the largest existing one?
> >
> > Just curious.
> >
>
> So that came from a discussion with Michael about which bit to use for
> this, and he suggested using 63:
>
> "
> Transports started from bit 24 and are growing up.
> So I would say devices should start from bit 63 and grow down.
> "
>
> https://patchwork.ozlabs.org/patch/848814/#1826669
>
> I will add a comment to explain it.
Maybe in the commit log. I don't think we need it in the header.
> Thanks,
>
> -Jason
- Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor,
Michael S. Tsirkin <=