From: Gary Hade <garyhade@us.ibm.com>
To: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>,
Tony Luck <tony.luck@intel.com>,
linuxppc-dev@ozlabs.org, linux-pci@vger.kernel.org,
Peter Haight <peterh@sapros.com>, Gary Hade <garyhade@us.ibm.com>,
linux-kernel@vger.kernel.org,
Jesse Barnes <jbarnes@virtuousgeek.org>,
linux-acpi@vger.kernel.org, linux-am33-list@redhat.com,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Yinghai Lu <yinghai@kernel.org>,
Larry Finger <Larry.Finger@lwfinger.net>
Subject: Re: [PATCH v4 0/5] PCI: try "pci=use_crs" again
Date: Thu, 18 Feb 2010 16:58:36 -0800 [thread overview]
Message-ID: <20100219005836.GA26564@us.ibm.com> (raw)
In-Reply-To: <20100217201654.4013.70201.stgit@bob.kio>
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 <garyhade@us.ibm.com>
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
prev parent reply other threads:[~2010-02-19 0:58 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-17 20:19 [PATCH v4 0/5] PCI: try "pci=use_crs" again Bjorn Helgaas
2010-02-17 20:19 ` [PATCH v4 1/5] PCI: split up pci_read_bridge_bases() Bjorn Helgaas
2010-02-23 0:23 ` Jesse Barnes
2010-02-23 1:13 ` Jesse Barnes
2010-02-17 20:19 ` [PATCH v4 2/5] PCI: read bridge windows before filling in subtractive decode resources Bjorn Helgaas
2010-02-17 20:20 ` [PATCH v4 3/5] PCI: add pci_bus_for_each_resource(), remove direct bus->resource[] refs Bjorn Helgaas
2010-02-17 20:20 ` [PATCH v4 4/5] PCI: augment bus resource table with a list Bjorn Helgaas
2010-02-23 16:08 ` Bjorn Helgaas
2010-02-17 20:20 ` [PATCH v4 5/5] x86/PCI: use host bridge _CRS info by default on 2008 and newer machines Bjorn Helgaas
2010-02-19 0:58 ` Gary Hade [this message]
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