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@xxxxxxxxxx> Gary -- Gary Hade System x Enablement IBM Linux Technology Center 503-578-4503 IBM T/L: 775-4503 garyhade@xxxxxxxxxx http://www.ibm.com/linux/ltc -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
