From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:48357)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <stefanha@gmail.com>) id 1TTXVZ-0002IC-Ul
	for qemu-devel@nongnu.org; Wed, 31 Oct 2012 08:34:59 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <stefanha@gmail.com>) id 1TTXVT-0002Rw-Sr
	for qemu-devel@nongnu.org; Wed, 31 Oct 2012 08:34:57 -0400
Received: from mail-lb0-f173.google.com ([209.85.217.173]:42039)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <stefanha@gmail.com>) id 1TTXVT-0002PC-LQ
	for qemu-devel@nongnu.org; Wed, 31 Oct 2012 08:34:51 -0400
Received: by mail-lb0-f173.google.com with SMTP id gj3so955491lbb.4
	for <qemu-devel@nongnu.org>; Wed, 31 Oct 2012 05:34:50 -0700 (PDT)
MIME-Version: 1.0
In-Reply-To: <50911ABA.4050003@redhat.com>
References: <1348226255-4226-1-git-send-email-vasilis.liaskovitis@profitbricks.com>
	<1348226255-4226-6-git-send-email-vasilis.liaskovitis@profitbricks.com>
	<20121023122532.GE19977@stefanha-thinkpad.redhat.com>
	<CAJnKYQk7k=AFpN1LwzDpuOYZcLmYNAaG3BPCBmNDDa+brFWJJQ@mail.gmail.com>
	<50910848.7000002@redhat.com>
	<CAJSP0QULwAE=tis-1fhW1yDCGiVK_F8pMij6eRPs4r4XTCWzhg@mail.gmail.com>
	<50911ABA.4050003@redhat.com>
Date: Wed, 31 Oct 2012 13:34:49 +0100
Message-ID: <CAJSP0QVFW4DvqRqUHVUoRiXoFqROXMULnRfD9MMRrKCH6k9Zfg@mail.gmail.com>
From: Stefan Hajnoczi <stefanha@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Subject: Re: [Qemu-devel] [RFC PATCH v3 05/19] Implement dimm device
	abstraction
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Avi Kivity <avi@redhat.com>
Cc: blauwirbel@gmail.com, kvm@vger.kernel.org, gleb@redhat.com, seabios@seabios.org, liu ping fan <qemulist@gmail.com>, qemu-devel@nongnu.org, Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>, kevin@koconnor.net, kraxel@redhat.com, anthony@codemonkey.ws, imammedo@redhat.com, Paolo Bonzini <pbonzini@redhat.com>

On Wed, Oct 31, 2012 at 1:34 PM, Avi Kivity <avi@redhat.com> wrote:
> On 10/31/2012 02:18 PM, Stefan Hajnoczi wrote:
>>>
>>> IMO we should use the same mechanism as proposed for other devices:
>>> address_space_map() should grab a reference on the dimm device, and
>>> address_space_unmap() can release it.  This way device destruction will
>>> be deferred as soon as all devices complete I/O.
>>>
>>> We will have to be careful with network receive buffers though, since
>>> they can be held indefinitely.
>>
>> Network receive buffers aren't mapped.  Net receive is not zero-copy.
>> For example, virtio-net does virtqueue_pop() inside
>> virtio_net_receive().
>>
>> I don't see a problem with networking.
>
> What about vhost-net?  But that is managed separately with a MemoryListener.

Yep.  It should find out when memory regions change through its listener.

Stefan