From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Prof. Dr. Klaus Kusche" Subject: Re: [Feature request] Multiple X servers on one graphics card? Date: Tue, 02 Aug 2011 10:17:53 +0200 Message-ID: <4E37B2B1.5040305@computerix.info> References: <4E3451E9.6000309@computerix.info> <4E37015E.10004@computerix.info> <20110801212256.4d34b7f2@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" Content-Transfer-Encoding: quoted-printable Return-path: Received: from www74.your-server.de (www74.your-server.de [213.133.104.74]) by gabe.freedesktop.org (Postfix) with ESMTP id 2A5489E99B for ; Tue, 2 Aug 2011 01:18:06 -0700 (PDT) In-Reply-To: <20110801212256.4d34b7f2@lxorguk.ukuu.org.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org Errors-To: dri-devel-bounces+sf-dri-devel=m.gmane.org@lists.freedesktop.org To: Alan Cox Cc: dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org On 2011-08-01 22:22, Alan Cox wrote: > There are also some interesting security issues with a lot of GPUs where > you'd be very very hard pushed to stop one task spying on the display of > another as there isn't much in the way of MMU contexts on the GPU side. > > Alan But I believe this is a problem of all approaches which provide multiple hardware-accelerated (or Xv-enabled) seats on a single GPU, no matter if based on multiple DRM devices, on Xephyr or Xnest with some kind of OpenGL or DRI passthrough, or on Wayland: If one has direct access to the graphics engine, he also can access any video memory he wants. Hence, that's no argument against multiple DRM devices on a single card, because the other solutions suffer from the same problem. In the long term, it needs to be fixed, but in a classroom environment, that's not my primary concern (and I believe 90 % of all multiseat installations will be classroom or home environments). Klaus. -- = Prof. Dr. Klaus Kusche Private address: Rainstra=DFe 9/1, 88316 Isny, Germany +49 7562 6211377 Klaus.Kusche@computerix.info http://www.computerix.info Office address: NTA Isny gGmbH, Seidenstra=DFe 12-35, 88316 Isny, Germany +49 7562 9707 36 kusche@nta-isny.de http://www.nta-isny.de