From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:56701) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Sycwt-0002gR-18 for qemu-devel@nongnu.org; Tue, 07 Aug 2012 02:07:23 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Sycws-0007wH-0w for qemu-devel@nongnu.org; Tue, 07 Aug 2012 02:07:22 -0400 Received: from gate.crashing.org ([63.228.1.57]:59804) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Sycwr-0007w2-Oh for qemu-devel@nongnu.org; Tue, 07 Aug 2012 02:07:21 -0400 Message-ID: <1344319635.2698.14.camel@pasglop> From: Benjamin Herrenschmidt Date: Tue, 07 Aug 2012 16:07:15 +1000 In-Reply-To: <5020A800.9010902@redhat.com> References: <1343629462.21647.32.camel@pasglop> <50165D0A.6060608@redhat.com> <1343647217.21647.40.camel@pasglop> <50166F2A.1040507@redhat.com> <1343649267.21647.44.camel@pasglop> <501676D7.3010504@redhat.com> <878ve11j70.fsf@codemonkey.ws> <501FC480.8060707@redhat.com> <1344287768.24037.107.camel@pasglop> <5020A800.9010902@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Subject: Re: [Qemu-devel] Cirrus bugs vs endian: how two bugs cancel each other out List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: Avi Kivity , Anthony Liguori , qemu-devel@nongnu.org On Tue, 2012-08-07 at 07:30 +0200, Gerd Hoffmann wrote: > On 08/06/12 23:16, Benjamin Herrenschmidt wrote: > > On Mon, 2012-08-06 at 15:20 +0200, Gerd Hoffmann wrote: > >> There are discussions about re-doing the guest/host interface (command > >> rings etc) now and then, by adding a qxl2 device (or maybe even extend > >> stdvga), dropping a bunch of backward compatibility stuff in qxl.c. > >> > >> Sending the spice commands over virtio is certainly an option here. > >> I'm > >> not sure it is possible to drive virtio rings from userspace (Xorg > >> driver), but that issue should go away with the qxl kms driver in the > >> works. > > > > Anything that gets rid of the qxl memory region API is welcome ;-) Some > > of that stuff is really gross. > > Well, it is needed for sanity checking memory references (to images etc) > in qxl commands, so we can't just zap it. But having a kms driver in > kernel space makes things easier again: You could simply register a > single memory region for the guest ram, then basically use guest > physical addresses for qxl memory references. qxl commands & data can > live in guest ram and you can stick references to the commands into > virtio rings ... Or you use a sane model in the first place that hides memory references behind object IDs :-) Yes, going via a KMS driver will go a long way toward fixing some of that. I would still like to experiment a bit if time permits with a different model which is basically GL paravirt via a virtio channel on top of virtio-vga (possibly limited to GL/ES at least initially). Guest side, we'd then have a simple DRM and use Glamor to turn all 2D rendering into GL. Cheers, Ben.