From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:44343)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1YSPvS-0007QL-GH
	for qemu-devel@nongnu.org; Mon, 02 Mar 2015 07:58:23 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1YSPvN-0000mr-I5
	for qemu-devel@nongnu.org; Mon, 02 Mar 2015 07:58:22 -0500
Received: from mx1.redhat.com ([209.132.183.28]:47583)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kraxel@redhat.com>) id 1YSPvN-0000mj-Ae
	for qemu-devel@nongnu.org; Mon, 02 Mar 2015 07:58:17 -0500
Message-ID: <1425301078.8058.8.camel@nilsson.home.kraxel.org>
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Mon, 02 Mar 2015 13:57:58 +0100
In-Reply-To: <CAPM=9tzSPNtbAe8sM-ji2UgrUM-iP7xj2CyDxfYPLYLgoQu-Zw@mail.gmail.com>
References: <1424687012-18524-1-git-send-email-kraxel@redhat.com>
	<1424687012-18524-7-git-send-email-kraxel@redhat.com>
	<54EF44F1.1090507@redhat.com>
	<CAPM=9tzSPNtbAe8sM-ji2UgrUM-iP7xj2CyDxfYPLYLgoQu-Zw@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [RfC PATCH 06/15] virtio-gpu/2d: add virtio gpu
 core code
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: Dave Airlie <airlied@gmail.com>
Cc: Dave Airlie <airlied@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Anthony Liguori <aliguori@amazon.com>, Max Reitz <mreitz@redhat.com>

  Hi,

> Gerd, btw I think we mighr want to support a set scanout with no
> resource, as it might make Linux atomic modesetting easier in the
> future, we'd just scanout black.

Makes sense, and should be easy to implement.

> > However, I think it's best to simply limit ab->nr_entries to some sane value
> > (I guess it shouldn't be even in the double digits for a single resource, so
> > restricting it to 256 or something seems sane to me...) and return an error
> > to the guest if that limit is exceeded.
> 
> please be careful about limiting this, limits should be pessimistic, as if the
> the GPU allocates one page per iov, so a 1280x1024x32bpp resource will
> have 1280 iovs.

I've already picked 1024 as 256 looked a bit low to me.  Guess we should
better go for 16k instead, that is enough even for ultra hd ...

cheers,
  Gerd