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authorGary Hade <garyhade@us.ibm.com>2008-05-12 13:57:46 -0700
committerJesse Barnes <jbarnes@virtuousgeek.org>2008-06-10 10:59:50 -0700
commitbb71ad880204b79d60331d3384103976e086cb9f (patch)
tree612b14aed172db36ddbdae2287ffdd65e6baef00 /arch/x86/pci/pci.h
parent5ca5c02f0e81c094c19d30dc0d13be4e929a994a (diff)
PCI: boot parameter to avoid expansion ROM memory allocation
Contention for scarce PCI memory resources has been growing due to an increasing number of PCI slots in large multi-node systems. The kernel currently attempts by default to allocate memory for all PCI expansion ROMs so there has also been an increasing number of PCI memory allocation failures seen on these systems. This occurs because the BIOS either (1) provides insufficient PCI memory resource for all the expansion ROMs or (2) provides adequate PCI memory resource for expansion ROMs but provides the space in kernel unexpected BIOS assigned P2P non-prefetch windows. The resulting PCI memory allocation failures may be benign when related to memory requests for expansion ROMs themselves but in some cases they can occur when attempting to allocate space for more critical BARs. This can happen when a successful expansion ROM allocation request consumes memory resource that was intended for a non-ROM BAR. We have seen this happen during PCI hotplug of an adapter that contains a P2P bridge where successful memory allocation for an expansion ROM BAR on device behind the bridge consumed memory that was intended for a non-ROM BAR on the P2P bridge. In all cases the allocation failure messages can be very confusing for users. This patch provides a new 'pci=norom' kernel boot parameter that can be used to disable the default PCI expansion ROM memory resource allocation. This provides a way to avoid the above described issues on systems that do not contain PCI devices for which drivers or user-level applications depend on the default PCI expansion ROM memory resource allocation behavior. Signed-off-by: Gary Hade <garyhade@us.ibm.com> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'arch/x86/pci/pci.h')
-rw-r--r--arch/x86/pci/pci.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/pci/pci.h b/arch/x86/pci/pci.h
index 720c4c55453..291dafec07b 100644
--- a/arch/x86/pci/pci.h
+++ b/arch/x86/pci/pci.h
@@ -27,6 +27,7 @@
#define PCI_CAN_SKIP_ISA_ALIGN 0x8000
#define PCI_USE__CRS 0x10000
#define PCI_CHECK_ENABLE_AMD_MMCONF 0x20000
+#define PCI_NOASSIGN_ROMS 0x40000
extern unsigned int pci_probe;
extern unsigned long pirq_table_addr;