Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758439AbZD0Ujy (ORCPT ); Mon, 27 Apr 2009 16:39:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761028AbZD0Ujm (ORCPT ); Mon, 27 Apr 2009 16:39:42 -0400 Received: from g1t0026.austin.hp.com ([15.216.28.33]:31138 "EHLO g1t0026.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759721AbZD0Ujk (ORCPT ); Mon, 27 Apr 2009 16:39:40 -0400 From: Bjorn Helgaas To: Yinghai Lu Subject: Re: [PATCH] x86/pci: do assign root bus res if _CRS is used Date: Mon, 27 Apr 2009 14:39:36 -0600 User-Agent: KMail/1.9.10 Cc: Jesse Barnes , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , "linux-kernel@vger.kernel.org" , linux-pci@vger.kernel.org, Gary Hade , Alex Chiang , linux-acpi@vger.kernel.org, Matthew Wilcox References: <49ED22EC.2040204@kernel.org> <200904271344.04099.bjorn.helgaas@hp.com> <49F61265.10201@kernel.org> In-Reply-To: <49F61265.10201@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200904271439.37396.bjorn.helgaas@hp.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2189 Lines: 59 On Monday 27 April 2009 02:15:33 pm Yinghai Lu wrote: > Bjorn Helgaas wrote: > > On Monday 20 April 2009 07:35:40 pm Yinghai Lu wrote: > >> it wil be overwriten later if _CRS is used, so don't bother to set it. > >> > >> [ Impact: cleanup ] > >> > >> Signed-off-by: Yinghai Lu > >> > >> --- > >> arch/x86/pci/amd_bus.c | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> Index: linux-2.6/arch/x86/pci/amd_bus.c > >> =================================================================== > >> --- linux-2.6.orig/arch/x86/pci/amd_bus.c > >> +++ linux-2.6/arch/x86/pci/amd_bus.c > >> @@ -100,6 +100,10 @@ void x86_pci_root_bus_res_quirks(struct > >> int j; > >> struct pci_root_info *info; > >> > >> + /* don't go for it if _CRS is used */ > >> + if (pci_probe & PCI_USE__CRS) > >> + return; > >> + > >> /* if only one root bus, don't need to anything */ > >> if (pci_root_num < 2) > >> return; > > > > This isn't a comment on this patch per se. > > > > I am concerned about the fact that "pci=use_crs" is not the default. > > From the changelog of 62f420f8282, it sounds like you have to boot an > > IBM x3850 with "pci=use_crs" to make hot-plug work, even though ACPI > > tells us everything we need to know. That's backwards. > > > > We shouldn't need an option to tell Linux that the firmware is > > trustworthy. We should have an option to *ignore* it for the times > > when we trip over something broken and haven't figured out a way to > > work around it yet. > > other system may have broken _CRS. Do you have examples of problems here, or are you just worried that there *may* be problems? > maybe we could try to use DMI whitelist them? I don't like a whitelist because it requires ongoing maintenance for correctly-working machines. A blacklist is nicer because it only requires maintenance for *broken* machines. A date-based solution would be better from that point of view. 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/