Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752520AbZIXN0w (ORCPT ); Thu, 24 Sep 2009 09:26:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752368AbZIXN0v (ORCPT ); Thu, 24 Sep 2009 09:26:51 -0400 Received: from g1t0029.austin.hp.com ([15.216.28.36]:29454 "EHLO g1t0029.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752231AbZIXN0v (ORCPT ); Thu, 24 Sep 2009 09:26:51 -0400 Subject: Re: fixing "pci=use_crs" From: Bjorn Helgaas To: Yinghai Lu Cc: Larry Finger , Gary Hade , Jesse Barnes , Jaswinder Singh Rajput , Thomas Gleixner , Ingo Molnar , Len Brown , Linus Torvalds , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <86802c440909232142p3e5d4974g51eb519d5d0ef58e@mail.gmail.com> References: <200909161715.24376.bjorn.helgaas@hp.com> <200909211520.56800.bjorn.helgaas@hp.com> <4AB95F41.1070500@lwfinger.net> <200909231723.31786.bjorn.helgaas@hp.com> <86802c440909231628t6b35aae4u706c0c35590bc0d3@mail.gmail.com> <1253762502.12653.4.camel@dc7800.home> <86802c440909232142p3e5d4974g51eb519d5d0ef58e@mail.gmail.com> Content-Type: text/plain Date: Thu, 24 Sep 2009 07:24:18 -0600 Message-Id: <1253798658.14132.9.camel@dc7800.home> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2542 Lines: 61 On Wed, 2009-09-23 at 21:42 -0700, Yinghai Lu wrote: > On Wed, Sep 23, 2009 at 8:21 PM, Bjorn Helgaas wrote: > > On Wed, 2009-09-23 at 16:28 -0700, Yinghai Lu wrote: > >> On Wed, Sep 23, 2009 at 4:23 PM, Bjorn Helgaas wrote: > > > >> > P.S. Yinghai, you posted some patches earlier dealing with "only one > >> > HT chain." You apparently have some insight into what's going on here, > >> > but unfortunately, the changelogs mean absolutely nothing to me. Can > >> > you give me any clues? > >> > >> which commit? > >> > >> normally we only need to have split root resource into several pieces > >> when we have two HT chains or other io chains... > > > > I meant the patches here: > > http://lkml.org/lkml/2009/6/24/557 > > > > My opinion is that ACPI is there to give us an abstract description of > > the machine, and we shouldn't have to introduce knowledge like "this > > machine has two HT chains" or add checks in amd_bus.c about > > "pci_root_num <= 1". > > > > But maybe if I knew what an HT chain was and why you think it affects > > the description returned by _CRS, it would give me a clue about how to > > deal with this in a generic way. > > we could use _CRS, but lots of BIOS just provide messed up resources > in _CRS to OS. We do have to assume there are BIOS defects here, but in most cases, I look for Linux deficiencies first. I'm assuming (without real evidence) that Windows does look at the _CRS, so the worst BIOS defects should be weeded out by Windows testing. > for example, the HW conf register does have mmio high range there, but > _CRS doesn't report them. On Larry's box, _CRS reports *more* ranges than Linux was prepared for. This would be a bug in the other direction, where _CRS reports *less* than it should. > thought we can use whilelist to use _CRS for them. I'm opposed to a whitelist for this issue because it means we have to continually update the whitelist for new, correctly working machines. If we can't figure out anything better, we could use a date-based blacklist (ignore _CRS for all machines older than today). But first, we have to establish that there really is a requirement to look at _CRS, then have a good try at making Linux smart enough to deal with whatever it finds. Bjorn -- 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/