From mboxrd@z Thu Jan 1 00:00:00 1970 From: Yinghai Lu Subject: Re: [PATCH] x86/pci: do assign root bus res if _CRS is used Date: Mon, 27 Apr 2009 13:15:33 -0700 Message-ID: <49F61265.10201@kernel.org> References: <49ED22EC.2040204@kernel.org> <200904271344.04099.bjorn.helgaas@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200904271344.04099.bjorn.helgaas@hp.com> Sender: linux-pci-owner@vger.kernel.org To: Bjorn Helgaas 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 List-Id: linux-acpi@vger.kernel.org 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. maybe we could try to use DMI whitelist them? YH