Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757158Ab0DIUbI (ORCPT ); Fri, 9 Apr 2010 16:31:08 -0400 Received: from imr2.ericy.com ([198.24.6.3]:38353 "EHLO imr2.ericy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757123Ab0DIUbE (ORCPT ); Fri, 9 Apr 2010 16:31:04 -0400 X-Greylist: delayed 5750 seconds by postgrey-1.27 at vger.kernel.org; Fri, 09 Apr 2010 16:31:04 EDT Subject: Re: [PATCH] x86: Reserve legacy VGA MMIO area for x86_64 as well as x86_32 From: Guenter Roeck Reply-To: guenter.roeck@ericsson.com To: "H. Peter Anvin" , linux-kernel@vger.kernel.org CC: Yinghai , Linus Torvalds , Bjorn Helgaas , Thomas Gleixner , Ingo Molnar , "linux-pci@vger.kernel.org" , "x86@kernel.org" , Andy Isaacson , Thomas Renninger In-Reply-To: <4BBF89FE.5040909@zytor.com> References: <20100407210628.28364.96982.stgit@bob.kio> <201004071705.07176.bjorn.helgaas@hp.com> <4BBD13C3.2060404@oracle.com> <201004091004.39857.bjorn.helgaas@hp.com> <4BBF5987.3010100@zytor.com> <4BBF626A.3060800@oracle.com> <4BBF70BC.3080809@zytor.com> <1270839357.1477.758.camel@groeck-laptop> <4BBF89FE.5040909@zytor.com> Content-Type: text/plain Organization: Ericsson Date: Fri, 9 Apr 2010 13:31:48 -0700 Message-ID: <1270845108.1477.784.camel@groeck-laptop> MIME-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1755 Lines: 48 On Fri, 2010-04-09 at 16:11 -0400, H. Peter Anvin wrote: > On 04/09/2010 11:55 AM, Guenter Roeck wrote: > > On Fri, 2010-04-09 at 14:23 -0400, H. Peter Anvin wrote: > >> [Adding Guenter Roeck as he was commenting on something writing to the > >> VGA area...] > >> > >> On 04/09/2010 10:22 AM, Yinghai wrote: > >>> > >>> then please check this one > >>> > >>> update e820 at first, and later put them resource tree, but give pci BAR chance to claim > >>> the range, before assign unassigned resources. > >>> > >>> in case some system doesn't have VGA, and use [0xa0000, ..] for mmio of some other pci devices. > >>> > >> > >> Do we have any evidence of any such system? > >> > >> Either which way, the patch looks saner... > >> > > Yes, we have a system which does not have VGA and uses the VGA memory > > space for another device. I don't know exactly what for, but I can find > > out if it is relevant. > > > > Quite. We really need to consider if that kind of devices should be > supported. It is used for a custom FPGA implementing a watchdog timer and some other functionality. This is not a matter of supporting such a device in Linux, it is a matter of explicitly excluding non-VGA devices from using VGA memory space. If that is the decision, it might be worthwhile mentioning it somewhere in the documentation, to prevent others from ever using that memory space in an embedded system (and to save them the time needed to find out about it and to identify and implement a workaround). Guenter -- 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/