From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: virtio_net: ethtool supported link modes Date: Fri, 1 Sep 2017 18:43:07 +0300 Message-ID: <20170901183517-mutt-send-email-mst@kernel.org> References: <1504199044.22080.11.camel@arista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Jason Wang , virtio-dev@lists.oasis-open.org To: Radu Rendec Return-path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Content-Disposition: inline In-Reply-To: <1504199044.22080.11.camel@arista.com> List-Id: netdev.vger.kernel.org On Thu, Aug 31, 2017 at 06:04:04PM +0100, Radu Rendec wrote: > Hello, > > Looking at the code in virtnet_set_link_ksettings, it seems the speed > and duplex can be set to any valid value. The driver will "remember" > them and report them back in virtnet_get_link_ksettings. > > However, the supported link modes (link_modes.supported in struct > ethtool_link_ksettings) is always 0, indicating that no speed/duplex > setting is supported. > > Does it make more sense to set (at least a few of) the supported link > modes, such as 10baseT_Half ... 10000baseT_Full? > > I would expect to see consistency between what is reported in > link_modes.supported and what can actually be set. Could you please > share your opinion on this? > > Thank you, > Radu Rendec I would like to know more about why this is desirable. We used not to support the modes at all, but it turned out some tools are confused by this: e.g. people would try to bond virtio with a hardware device, tools would see a mismatch in speed and features between bonded devices and get confused. See commit 16032be56c1f66770da15cb94f0eb366c37aff6e Author: Nikolay Aleksandrov Date: Wed Feb 3 04:04:37 2016 +0100 virtio_net: add ethtool support for set and get of settings as well as the discussion around it https://www.spinics.net/lists/netdev/msg362111.html If you think we need to add more hacks like this, a stronger motivation than "to see consistency" would be needed. -- MST