• Gary Hade's avatar
    PCI: remove default PCI expansion ROM memory allocation · 9f8dacca
    Gary Hade authored
    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 addresses the issue by changing the kernel default behavior
    so that expansion ROM memory allocations are no longer attempted by
    default when the BIOS has not assigned a specific address range to the
    expansion ROM BAR.  This was done by changing the 'pci=rom' boot option
    behavior for BIOS unassigned expansion ROMs to actually match it's
    current kernel-parameters.txt description which already implies "off" by
    default. Behavior for BIOS assigned expansion ROMs implemented in
    pcibios_assign_resources() [arch/x86/pci/i386.c] is unchanged.
    Signed-off-by: default avatarGary Hade <garyhade@us.ibm.com>
    Cc: Greg KH <greg@kroah.com>
    Cc: Jan Beulich <jbeulich@novell.com>
    Acked-by: default avatar"Jun'ichi Nomura" <j-nomura@ce.jp.nec.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    9f8dacca
common.c 12.5 KB