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Date:   Tue, 5 Oct 2021 07:22:23 -0400
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Halil Pasic <pasic@linux.ibm.com>
Cc:     Cornelia Huck <cohuck@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Xie Yongji <xieyongji@bytedance.com>,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, markver@us.ibm.com,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        linux-s390@vger.kernel.org, virtio-dev@lists.oasis-open.org
Subject: Re: [virtio-dev] Re: [RFC PATCH 1/1] virtio: write back features
 before verify
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On Tue, Oct 05, 2021 at 01:17:51PM +0200, Halil Pasic wrote:
> On Mon, 4 Oct 2021 16:01:12 -0400
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > > 
> > > Ok, so what about something like
> > > 
> > > "If FEATURES_OK is not set, the driver MAY change the set of features it
> > > accepts."
> > > 
> > > in the device initialization section?  
> > 
> > Maybe "as long as". However Halil implied that some features are not
> > turned off properly if that happens. Halil could you pls provide
> > some examples?
> 
> 
> 
> static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
> {
> ...
>     if (virtio_has_feature(features, VIRTIO_NET_F_STANDBY)) {
>         qapi_event_send_failover_negotiated(n->netclient_name);
>         qatomic_set(&n->failover_primary_hidden, false);
>         failover_add_primary(n, &err);
>         if (err) {
>             warn_report_err(err);
>         }
>     }
> }
> 
> This is probably the only one in QEMU. Back then I stopped looking
> after the first hit.
> 
> Regards,
> Halil

Hmm ok more failover issues :(
This stuff really should be moved to set_status.

-- 
MST