Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759339AbXHTMiL (ORCPT ); Mon, 20 Aug 2007 08:38:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757482AbXHTMhf (ORCPT ); Mon, 20 Aug 2007 08:37:35 -0400 Received: from nz-out-0506.google.com ([64.233.162.229]:23504 "EHLO nz-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755443AbXHTMgs (ORCPT ); Mon, 20 Aug 2007 08:36:48 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:mime-version:content-type:content-transfer-encoding:content-disposition; b=oby6wX8TZFW9aFW2jQDLAbnXOXd70xcxtGTQSe0ZB+bCMLC2CW10Qy1lUcntZwDMAj23hR3E9vq3CudqMJj5t1mJlUe86N40n6Ae+cAavm6oL5fHYDsTTqSgDLhtVPjeVf8wZvyZIwkduZykU9xHnUaepSc73bKdGrn5p5CrToQ= Message-ID: <6278d2220708200536r786ee72ere7522547c375a428@mail.gmail.com> Date: Mon, 20 Aug 2007 13:36:46 +0100 From: "Daniel J Blueman" To: "Dave Airlie" Subject: Re: uncached page allocator Cc: "Linux Kernel" MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1437 Lines: 37 On 20 Aug, 01:50, "Dave Airlie" wrote: > Hi all, > > I've started doing some work with using the new DRM memory manager > from TG for pixmaps in the X server using Intel 9xx series hardware. > > The intel hardware pretty much requires pages to be uncached for the > GPU to access them. It can use cached memory for some operations but > it isn't very useful and my attempts to use it ended in a lot of > crashiness.. Write-combining access seems the correct thing here, followed by a wmb(). Uncached writing would be horrendously slow. [snip] > So after all that I'd like to have some sort of uncached page list I > can allocate pages from This is exactly what Intel's PAT mechanism exists for - just mark the desired access type (index) on the pages you've been allocated. It's documented in the Intel Architecture Software Design manuals, but Linux's support is lacking in certain areas [discussions on LKML], which a number of developers have been trying to move forward. Quite a few significant graphics/HPC etc vendors are forced to use it without this complete support, so it would be good to get this additional impetus involved... Daniel -- Daniel J Blueman - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/