From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161125AbVKYPvs (ORCPT ); Fri, 25 Nov 2005 10:51:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161126AbVKYPvs (ORCPT ); Fri, 25 Nov 2005 10:51:48 -0500 Received: from clock-tower.bc.nu ([81.2.110.250]:47781 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1161125AbVKYPvr (ORCPT ); Fri, 25 Nov 2005 10:51:47 -0500 Subject: Re: 2.6.14-rt4: via DRM errors From: Alan Cox To: Lee Revell Cc: Thomas =?ISO-8859-1?Q?Hellstr=F6m?= , linux-kernel , Dave Airlie , "dri-devel@lists.sourceforge.net" In-Reply-To: <1132829378.3473.11.camel@mindpipe> References: <1132807985.1921.82.camel@mindpipe> <8964.192.138.116.230.1132825958.squirrel@192.138.116.230> <1132829378.3473.11.camel@mindpipe> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Fri, 25 Nov 2005 16:24:23 +0000 Message-Id: <1132935863.3298.36.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Iau, 2005-11-24 at 05:49 -0500, Lee Revell wrote: > BTW can you point me to a good explanation of DRM locking? There's so > much indirection in the DRM code I can't even tell whether there's one > DRM lock or several, what kind of lock it is or what it's protecting > (beyond "access to the hardware"). Is it just an advisory lock used by > DRM clients to keep from stepping on each other? It doesn't seem > related to spinlocks or mutexes or any of the other types of lock in the > kernel. It co-ordinates access between the X server and various 3D clients so that they don't step on each others drawing. A shared memory area is used to co-ordinate other things like clip lists and what context may have been stomped by another user if when you retake the lock you were not last holder. Precisely what it protects is board dependant