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From: Johannes Berg <johannes@sipsolutions.net>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [RFC v2 1/2] docs: vhost-user: add in-band kick/call messages
Date: Mon, 16 Sep 2019 13:40:35 +0200	[thread overview]
Message-ID: <674086baeed5fce100d0882e668d5e36f026bd71.camel@sipsolutions.net> (raw)
In-Reply-To: <fedd74ed3e9cc554287b202e73b047a938515113.camel@sipsolutions.net>

Hi Michael,

I had just wanted to prepare a resend, but

> > Hmm I don't like this. I propose that with VHOST_USER_PROTOCOL_F_IN_BAND_NOTIFICATIONS
> > we just don't allow VHOST_USER_SET_VRING_CALL (if you think it's
> > important to allow them, we can say that we do not require them).
> 
> You can't actually skip SET_VRING_CALL, it's necessary to start a vring,
> so libvhost-user for example calls dev->iface->queue_set_started() only
> in this case. The docs in the "Starting and stopping rings" section also
> explain this.

[...]

> See above. But I guess we could put a flag into bit 9 indicating that
> you want to use messages instead of polling or a file descriptor, if you
> prefer.

Personally, I don't think it matters since right now I can see the in-
band notification as being really necessary/useful only for simulation
work, and in that case no polling will be doable.

If you do think it's important to not make the two mutually exclusive,
how would you prefer to have this handled? With a new flag, e.g. in bit
9, indicating "use inband signalling instead of polling or eventfd"?

Thanks,
johannes



  reply	other threads:[~2019-09-16 11:41 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-11 13:45 [Qemu-devel] [RFC v2 0/2] vhost-user: in-band notifications Johannes Berg
2019-09-11 13:45 ` [Qemu-devel] [RFC v2 1/2] docs: vhost-user: add in-band kick/call messages Johannes Berg
2019-09-11 14:07   ` Michael S. Tsirkin
2019-09-11 15:09     ` Johannes Berg
2019-09-16 11:40       ` Johannes Berg [this message]
2019-09-16 15:30         ` Michael S. Tsirkin
2019-09-17 12:01           ` Johannes Berg
2019-09-11 19:15   ` Dr. David Alan Gilbert
2019-09-11 19:18     ` Johannes Berg
2019-09-12  8:09       ` Dr. David Alan Gilbert
2019-09-12  8:13         ` Johannes Berg
2019-09-11 13:45 ` [Qemu-devel] [RFC v2 2/2] libvhost-user: implement in-band notifications Johannes Berg
2019-09-11 15:01 ` [Qemu-devel] [RFC v2 0/2] vhost-user: " no-reply

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