Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753370AbYJCO6e (ORCPT ); Fri, 3 Oct 2008 10:58:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752335AbYJCO6W (ORCPT ); Fri, 3 Oct 2008 10:58:22 -0400 Received: from gw-d.mimosa.com ([209.161.207.149]:55616 "EHLO gw-d.mimosa.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752429AbYJCO6V (ORCPT ); Fri, 3 Oct 2008 10:58:21 -0400 Date: Fri, 3 Oct 2008 10:57:41 -0400 (EDT) From: "D. Hugh Redelmeier" Reply-To: "D. Hugh Redelmeier" To: "H. Peter Anvin" cc: Ingo Molnar , =?ISO-8859-15?Q?=22J=2EA=2E_Magall=F3n=22?= , Linux-Kernel , Yinghai Lu , Thomas Gleixner Subject: Re: [PATCH 2/2] x86: mtrr_cleanup try gran_size to less than 1M In-Reply-To: <48E5CBFC.3090702@zytor.com> Message-ID: References: <1222739652-17169-1-git-send-email-yhlu.kernel@gmail.com> <1222739652-17169-2-git-send-email-yhlu.kernel@gmail.com> <20081003003237.04469201@werewolf.home> <20081003073727.GC4950@elte.hu> <48E5CBFC.3090702@zytor.com> User-Agent: Alpine 2.00 (LRH 1167 2008-08-23) MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-1603562624-1223045862=:4688" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2191 Lines: 56 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-1603562624-1223045862=:4688 Content-Type: TEXT/PLAIN; charset=UTF-8 Content-Transfer-Encoding: 8BIT | From: H. Peter Anvin | Ingo Molnar wrote: | > * J.A. Magallón wrote: | > > +++ arch/x86/kernel/cpu/mtrr/if.c 2008-10-03 00:22:34.000000000 +0200 | > > @@ -16,7 +16,7 @@ | > > static const char *const mtrr_strings[MTRR_NUM_TYPES] = | > > { | > > "uncachable", /* 0 */ | > > - "write-combining", /* 1 */ | > > + "write-combine", /* 1 */ | > | > hm, maybe this bit could confuse versions of Xorg that modifies /proc/mtrr - | > i.e. this could be part of the ABI towards user-space. We'll see. | > | | This *IS* part of the ABI toward userspace, although I think Xorg uses the | ioctl() interface. My mtrr-uncover program uses this interface. One reason is that the ioctl interface is broken. See http://lkml.org/lkml/2008/8/5/62 I too understand that Xorg drivers uses the ioctl interface. Since they only use it on video device buffers, and those buffers always seem to start and end below 4GiB, the ioctl bugs probably don't affect Xorg. The ioctl bugs do mean that Xorg drivers cannot even see the MTRR nesting problems let alone address them. The ib_path driver apparently uses MTRRs in a way analogous to Xorg drivers. There is a script that is part of Fedora that uses the /proc/mtrr interface to attempt to fix nested MTRRs: http://cvs.fedora.redhat.com/viewvc/devel/rdma/rdma-fixup-mtrr.awk There may well be other users of this API. Or is it an ABI. I'm not sure. It would be useful to know what code exists that uses the MTRR-changing interfaces. I only know about the ones I've mentioned above. Does anyone know of others? --8323328-1603562624-1223045862=:4688-- -- 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/