From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gary Hade Subject: Re: [PATCH v4 0/5] PCI: try "pci=use_crs" again Date: Thu, 18 Feb 2010 16:58:36 -0800 Message-ID: <20100219005836.GA26564@us.ibm.com> References: <20100217201654.4013.70201.stgit@bob.kio> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from e37.co.us.ibm.com ([32.97.110.158]:53151 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750717Ab0BSA6s (ORCPT ); Thu, 18 Feb 2010 19:58:48 -0500 Content-Disposition: inline In-Reply-To: <20100217201654.4013.70201.stgit@bob.kio> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Bjorn Helgaas Cc: Jesse Barnes , Matthew Garrett , Tony Luck , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, Peter Haight , Gary Hade , linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org, linux-am33-list@redhat.com, Yinghai Lu , Ingo Molnar , Linus Torvalds , Larry Finger On Wed, Feb 17, 2010 at 01:19:47PM -0700, Bjorn Helgaas wrote: > Historically, Linux has assumed a single PCI host bridge, with that bridge > claiming all the address space left after RAM and legacy devices are taken out. > > If the system contains multiple host bridges, we can no longer operate under > that assumption. We have to know what parts of the address space are claimed > by each bridge so that when we assign resources to a PCI device, we take them > from a range claimed by the upstream host bridge. > > On x86 and ia64, we use ACPI to enumerate all the PCI host bridges in the > system, and part of the host bridge description is the "_CRS" (current resource > settings" property, which lists the address space used by the bridge. On x86, > we currently ignore most of the _CRS information. This patch series changes > this, so we will use _CRS to learn about the host bridge windows. > > Since most x86 machines with multiple host bridges are relatively new, this > series only turns this on for machines with BIOS dates of 2008 or newer. I just tried your changes on an IBM x3850 with a 12/01/2008 BIOS date. After booting without pci=use_crs I observed the expected PCI: Using host bridge windows from ACPI; if necessary, use "pci=nocrs" and report a bug message. I then loaded 'acpiphp' and was able to successfully hot-remove and hot-add PCI-X and PCIe cards. Without pci=use_crs a hot-add operation would have previously caused a machine check. Tested-by: Gary Hade 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