Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760243AbZD3AG0 (ORCPT ); Wed, 29 Apr 2009 20:06:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754496AbZD3AGP (ORCPT ); Wed, 29 Apr 2009 20:06:15 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.144]:39303 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753140AbZD3AGO (ORCPT ); Wed, 29 Apr 2009 20:06:14 -0400 Date: Wed, 29 Apr 2009 17:06:11 -0700 From: Gary Hade To: Bjorn Helgaas Cc: Yinghai Lu , 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 Subject: Re: [PATCH] x86/pci: do assign root bus res if _CRS is used Message-ID: <20090430000611.GA22030@us.ibm.com> References: <49ED22EC.2040204@kernel.org> <200904271344.04099.bjorn.helgaas@hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200904271344.04099.bjorn.helgaas@hp.com> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2299 Lines: 68 On Mon, Apr 27, 2009 at 01:44:01PM -0600, 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. Sorry, I am behind on my email and just noticed this. When I posted the patches to add "pci=use_crs" it was only needed to enable PCI hotplug on a subset of our systems. At that time it was not apparent that others were interested. I was also concerned that real or anticipated breakage on on other systems might delay or prevent acceptance. As long as there is an option to disable it I am also in favor of trying to make it the default. Thanks! Gary -- Gary Hade System x Enablement IBM Linux Technology Center 503-578-4503 IBM T/L: 775-4503 garyhade@us.ibm.com http://www.ibm.com/linux/ltc -- 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/