Date:   Sun, 5 Mar 2023 04:53:58 -0500
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Jakub Kicinski <kuba@kernel.org>
Cc:     Jason Wang <jasowang@redhat.com>, rbradford@rivosinc.com,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] virtio-net: Fix probe of virtio-net on kvmtool
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On Fri, Mar 03, 2023 at 04:46:03PM -0800, Jakub Kicinski wrote:
> On Thu, 2 Mar 2023 04:48:38 -0500 Michael S. Tsirkin wrote:
> > > Looks not the core can try to enable and disable features according to
> > > the diff between features and hw_features
> > > 
> > > static inline netdev_features_t netdev_get_wanted_features(
> > >         struct net_device *dev)
> > > {
> > >         return (dev->features & ~dev->hw_features) | dev->wanted_features;
> > > }
> > 
> > yes what we do work according to code.  So the documentation is wrong then?
> 
> It's definitely incomplete but which part are you saying is wrong?

So it says:
  2. netdev->features set contains features which are currently enabled
     for a device.

ok so far.
But this part:

  This should be changed only by network core or in
     error paths of ndo_set_features callback.

seems to say virtio should not touch netdev->features, no?

-- 
MST