From: "Michael S. Tsirkin" <mst@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>,
Changpeng Liu <changpeng.liu@intel.com>,
qemu-devel@nongnu.org, marcandre.lureau@redhat.com,
felipe@nutanix.com, james.r.harris@intel.com
Subject: Re: [Qemu-devel] [PATCH v5 1/4] vhost-user: add new vhost user messages to support virtio config space
Date: Tue, 21 Nov 2017 05:12:58 +0200 [thread overview]
Message-ID: <20171121051156-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <776f5005-8bb8-773a-1f16-56b5675e7d74@redhat.com>
On Tue, Nov 21, 2017 at 01:16:12AM +0100, Paolo Bonzini wrote:
> On 20/11/2017 21:44, Michael S. Tsirkin wrote:
> > Live migrations is supposed to be migrating guest writeable state too.
> > If you mean migrating RO fields like size, then
> > I don't think it's a good idea to reuse SET_CONFIG for that.
> > SET_CONFIG should obey exactly the virtio semantics.
> >
> > And I agree, it should say that slave must treat it as a write,
> > and get config as a read according to virtio semantics.
> >
> > If someone needs to pass configuration from qemu to
> > slave, let's add specific messages with precisely defined semantics.
>
> Fair enough, but I'd add nevertheless a 32-bit flags field to both
> GET_CONFIG and SET_CONFIG, and document that the slave MUST check that
> it is zero and otherwise fail.
>
> Paolo
We generally just use protocol feature bits for extensions.
But I have no problem with reserved padding if desired
which seems to be what's described here.
--
MST
next prev parent reply other threads:[~2017-11-21 3:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-16 20:44 [Qemu-devel] [PATCH v5 0/4] *** Introduce a new vhost-user-blk host device to Qemu *** Changpeng Liu
2017-11-16 20:44 ` [Qemu-devel] [PATCH v5 1/4] vhost-user: add new vhost user messages to support virtio config space Changpeng Liu
2017-11-20 16:26 ` Stefan Hajnoczi
2017-11-20 20:44 ` Michael S. Tsirkin
2017-11-21 0:16 ` Paolo Bonzini
2017-11-21 3:12 ` Michael S. Tsirkin [this message]
2017-11-22 14:36 ` Paolo Bonzini
2017-11-22 2:27 ` Liu, Changpeng
2017-11-22 2:28 ` Liu, Changpeng
2017-11-22 2:25 ` Liu, Changpeng
2017-11-22 14:49 ` Michael S. Tsirkin
2017-11-16 20:44 ` [Qemu-devel] [PATCH v5 2/4] vhost-user-blk: introduce a new vhost-user-blk host device Changpeng Liu
2017-11-16 20:44 ` [Qemu-devel] [PATCH v5 3/4] contrib/libvhost-user: enable virtio config space messages Changpeng Liu
2017-11-16 20:44 ` [Qemu-devel] [PATCH v5 4/4] contrib/vhost-user-blk: introduce a vhost-user-blk sample application Changpeng Liu
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