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Date: Mon, 18 Aug 2014 13:42:23 +0200
From: William Dauchy <william@gandi.net>
Message-ID: <20140818114223.GA13779@gandi.net>
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Subject: [Qemu-devel] vhost-net issue with multiples interfaces using MQ
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Hello,

Using qemu2.1.0, a linux v3.14.X x86_64 as host and a linux v3.12.X x86_64 =
as guest
I'm starting a VM with these network interfaces:

[netdev "vifA.0"]
=A0 type =3D "tap"
=A0 vhost =3D "on"
=A0 ifname =3D "vifA.0"
=A0 downscript =3D "no"
=A0 script =3D "no"
=A0 queues =3D "2"

[device "vifA.0"]
=A0 driver =3D "virtio-net-pci"
=A0 netdev =3D "vifA.0"
=A0 mac =3D "00:16:3e:1a:4e:11"
=A0 mq =3D "on"
=A0 vectors =3D "5"

(and same config for two other interfaces but with a different MAC address)

In the error message I'm getting during startup:
unable to start vhost net: 95: falling back on userspace virtio

I saw that it's failing in `vhost_dev_start` where `vhost_dev_set_features`=
 is returning an error.
r =3D vhost_dev_set_features(hdev, hdev->log_enabled);
I'm hitting the issue starting from three interfaces, i.e no problem with o=
ne or two.
I also don't have the issue with disabling multi queue.

Am I wrong on something? What can I do to help debug this situation?

Regards,
--=20
William

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