From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755621AbZHKXRu (ORCPT ); Tue, 11 Aug 2009 19:17:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755605AbZHKXRt (ORCPT ); Tue, 11 Aug 2009 19:17:49 -0400 Received: from mga09.intel.com ([134.134.136.24]:26566 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755599AbZHKXRs (ORCPT ); Tue, 11 Aug 2009 19:17:48 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.43,363,1246863600"; d="scan'208";a="438155136" Date: Tue, 11 Aug 2009 16:17:46 -0700 From: Jesse Barnes To: Dave Airlie Cc: Benjamin Herrenschmidt , linux-kernel@vger.kernel.org, dri-devel@lists.sf.net, Tiago Vignatti Subject: Re: [PATCH] vga: implements VGA arbitration on Linux Message-ID: <20090811161746.7b8878aa@jbarnes-g45> In-Reply-To: <1249969927-884-1-git-send-email-airlied@gmail.com> References: <1249969927-884-1-git-send-email-airlied@gmail.com> X-Mailer: Claws Mail 3.7.2 (GTK+ 2.17.5; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 11 Aug 2009 15:52:06 +1000 Dave Airlie wrote: > From: Tiago Vignatti > > Background: > Graphic devices are accessed through ranges in I/O or memory space. > While most modern devices allow relocation of such ranges, some > "Legacy" VGA devices implemented on PCI will typically have the same > "hard-decoded" addresses as they did on ISA. For more details see > "PCI Bus Binding to IEEE Std 1275-1994 Standard for Boot > (Initialization Configuration) Firmware Revision 2.1" Section 7, > Legacy Devices. > > The Resource Access Control (RAC) module inside the X server > currently does the task of arbitration when more than one legacy > device co-exists on the same machine. But the problem happens when > these devices are trying to be accessed by different userspace > clients (e.g. two server in parallel). Their address assignments > conflict. Therefore an arbitration scheme _outside_ of the X server > is needed to control the sharing of these resources. This document > introduces the operation of the VGA arbiter implemented for Linux > kernel. > > Signed-off-by: Tiago Vignatti > Signed-off-by: Dave Airlie Ok, applied this to my linux-next branch, but I'd like to get Ben's s-o-b before pushing it to Linus. Ben? Thanks, -- Jesse Barnes, Intel Open Source Technology Center