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From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: virtio-net mq vq initialization
Date: Sun, 14 Apr 2013 21:35:56 +0300
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Cc: Rusty Russell <rusty@rustcorp.com.au>,
	Will Deacon <will.deacon@arm.com>, kvm@vger.kernel.org,
	penberg@kernel.org, marc.zyngier@arm.com
To: Sasha Levin <sasha.levin@oracle.com>
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On Sun, Apr 14, 2013 at 11:59:42AM -0400, Sasha Levin wrote:
> On 04/14/2013 11:53 AM, Michael S. Tsirkin wrote:
> >> >=20
> >> > Initializing them only when they're actually needed will do the =
trick here.
> > Not initializing, adding the buffers. In the current spec, initiali=
zation
> > is always done before DRIVER_OK.
>=20
> Yeah, that's better, but we're going to need a spec change either way=
 since even
> adding the buffers is specifically stated to happen before DRIVER_OK:
>=20
> """
> 	6. The receive virtqueues should be filled with receive buffers. Thi=
s is described
> in detail below in =E2=80=9CSetting Up Receive Buffers=E2=80=9D.
> """
>=20
> Thanks,
> Sasha

Yes but that's a minor point, specific to virio-net.
The main point was to ensure that VQs should have buffers before they g=
et
any packets.

OTOH VQ init bere DRIVER_OK is a generic virtio thing: DRIVER_OK means
we can start sending interrupts and we expect driver to be ready to get
them.

Let's solve the real problem with buffers, a couple of pages per VQ
shouldn't be an issue.

--=20
MST