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62f420f828
Use _CRS for PCI resource allocation This patch resolves an issue where incorrect PCI memory and i/o ranges are being assigned to hotplugged PCI devices on some IBM systems. The resource mis-allocation not only makes the PCI device unuseable but often makes the entire system unuseable due to resulting machine checks. The hotplug capable PCI slots on the affected systems are not located under a standard P2P bridge but are instead located under PCI root bridges or subtractive decode P2P bridges. For example, the IBM x3850 contains 2 hotplug capable PCI-X slots and 4 hotplug capable PCIe slots with the PCI-X slots each located under a PCI root bridge and the PCIe slots each located under a subtractive decode P2P bridge. The current i386/x86_64 PCI resource allocation code does not use _CRS returned resource information. No other resource information source is available for slots that are not below a standard P2P bridge so incorrect ranges are being allocated from e820 hole causing the bad result. This patch causes the kernel to use _CRS returned resource info. It is roughly based on a change provided by Matthew Wilcox for the ia64 kernel in 2005. Due to possible buggy BIOS factor and possible yet to be discovered kernel issues the function is disabled by default and can be enabled with pci=use_crs. Signed-off-by: Gary Hade <gary.hade@us.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
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