Re: [PATCH net-next] hv_netvsc: add ethtool support for set and get of settings

[David Miller]

From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Date: Mon, 29 Feb 2016 22:34:38 +0000

> On Mon, 2016-02-29 at 17:09 -0500, David Miller wrote:
>> From: Simon Xiao <sixiao@xxxxxxxxxxxxx>
>> Date: Thu, 25 Feb 2016 15:24:08 -0800
>> 
>> > This patch allows the user to set and retrieve speed and duplex of the
>> > hv_netvsc device via ethtool.
>> > 
>> > Example:
>> > $ ethtool eth0
>> > Settings for eth0:
>> > ...
>> >     Speed: Unknown!
>> >     Duplex: Unknown! (255)
>> > ...
>> > $ ethtool -s eth0 speed 1000 duplex full
>> > $ ethtool eth0
>> > Settings for eth0:
>> > ...
>> >     Speed: 1000Mb/s
>> >     Duplex: Full
>> > ...
>> > 
>> > This is based on patches by Roopa Prabhu and Nikolay Aleksandrov.
>> > 
>> > Signed-off-by: Simon Xiao <sixiao@xxxxxxxxxxxxx>
>> 
>> Applied, thanks.
> 
> I missed this due to flu, but now I look at it - I don't see the point.
> Link speed isn't meaingful for a memory-based transport, so "unknown"
> is correct.  The link is effectively full duplex though.
> 
> If the issue is that ethtool is a bit shouty about unknowns, let's
> consider changing that in ethtool, not teaching drivers to lie.

The issue is that certain bonding modes do not work properly without
a speed being reported by a device.

We're doing this for other "virtual" devices already thanks to changes
that went in last week, so there is precedence.