Description of problem:
When loading a driver for a PCIe device which supports SR-IOV, the BARs
associated with the SR-IOV capability may not be reliably requested, even if
there is space.
The bug is similar (identical?) to 523341
(https://bugzilla.redhat.com/show_bug.cgi?id=523341)

Version-Release number of selected component (if applicable):
RHEL 5.5 2.6.18-190.el5xen

How reproducible:
Platform dependent, but when it happens it happens 100% of the time.


Steps to Reproduce:
1. Enable SR-IOV in system BIOS
2. Boot RHEL-5.4
3. Load relevant driver (for SR-IOV capable device)
  
Actual results:
Driver modprobe fails and produces an error like:
“PCI: Failed to allocate mem resource #12:1800000@b4800000 for 0000:02:00.0
vxge 0000:02:00.0: not enough MMIO resources for SR-IOV”

This means the physical device (aka Physical Function or PF) will not work,
and, of course, no virtual devices (aka Virtual Function or VF) associated w/
that PF can be allocated.

Expected results:
Driver is successfully loaded and VFs are successfully allocated making both
the PF and its VFs functional.

Additional info: