Description of problem:
when I executed "modprobe -r ixgbe; modprobe ixgbe max_vfs=2" to create SR-IOV VF,
these error messages occurred:
...
PCI: Enabling device 0000:11:00.0 (0040 -> 0042)
ixgbe 0000:11:00.0: not enough MMIO resources for SR-IOV
ixgbe 0000:11:00.0: (unregistered net_device): Failed to enable PCI sriov: -12
PCI: Enabling device 0000:11:00.1 (0040 -> 0042)
ixgbe 0000:11:00.1: not enough MMIO resources for SR-IOV
ixgbe 0000:11:00.1: (unregistered net_device): Failed to enable PCI sriov: -12

and I did the same actions on the two machines:
hp-dl580g7-01.rhts.eng.nay.redhat.com
sun-cp3270-01.rhts.eng.bos.redhat.com
the result was similar.
also I found the PCI messages when the system boot:
...
...
15200n81 rhgb quiet
   [Linux-bzImage, setup=0x1e00, size=0x20203c]
initrd /initrd-2.6.18-294.el5.img
   [Linux-initrd @ 0x37c49000, 0x3a6063 bytes]

Memory for crash kernel (0x0 to 0x0) notwithin permissible range
PCI: Failed to allocate mem resource #12:100000@0 for 0000:11:00.0
PCI: Failed to allocate mem resource #15:100000@0 for 0000:11:00.0
PCI: Failed to allocate mem resource #12:100000@0 for 0000:11:00.1
PCI: Failed to allocate mem resource #15:100000@0 for 0000:11:00.1
�Red Hat nash version 5.1.19.6 starting
  Reading all physical volumes.  This may take a while...
  Found volume group "VolGroup00" using metadata type lvm2
  2 logical volume(s) in volume group "VolGroup00" now active
		Welcome to Red Hat Enterprise Linux Server
		Press 'I' to enter interactive startup.
Setting clock  (localtime): Thu Nov 17 03:56:13 EST 2011 [  OK  ]
Starting udev: [  OK  ]
Loading default keymap (us): [  OK  ]
Setting hostname hp-dl580g7-01.rhts.eng.nay.redhat.com:  [  OK  ]
Setting up Logical Volume Management:   2 logical volume(s) in volume group "VolGroup00" now active
...
...
FYI: I guessed the "PCI: Failed" maybe caused the bug.

Version-Release number of selected component (if applicable):
CPU: intel Xeon
os tree: RHEL5.8-Server-20111030.0
[root@hp-dl580g7-01 ~]# cat /proc/cmdline 
ro root=/dev/VolGroup00/LogVol00 console=ttyS0,115200n81 intel_iommu=on rhgb quiet
[root@hp-dl580g7-01 ~]# lspci | grep Eth
04:00.0 Ethernet controller: NetXen Incorporated NX3031 Multifunction 1/10-Gigabit Server Adapter (rev 42)
04:00.1 Ethernet controller: NetXen Incorporated NX3031 Multifunction 1/10-Gigabit Server Adapter (rev 42)
04:00.2 Ethernet controller: NetXen Incorporated NX3031 Multifunction 1/10-Gigabit Server Adapter (rev 42)
04:00.3 Ethernet controller: NetXen Incorporated NX3031 Multifunction 1/10-Gigabit Server Adapter (rev 42)
0b:00.0 Ethernet controller: Emulex Corporation OneConnect 10Gb NIC (rev 02)
0b:00.1 Ethernet controller: Emulex Corporation OneConnect 10Gb NIC (rev 02)
11:00.0 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01)
11:00.1 Ethernet controller: Intel Corporation 82599EB 10-Gigabit SFI/SFP+ Network Connection (rev 01)
[root@hp-dl580g7-01 ~]# uname -ri
2.6.18-294.el5 x86_64

How reproducible:


Steps to Reproduce:
1. add intel_iommu=on to kernel command line, reboot
2. # modprobe -r ixgbe; modprobe ixgbe max_vfs=number
3. # dmesg
  
Actual results:
...
ixgbe 0000:11:00.1: not enough MMIO resources for SR-IOV
ixgbe 0000:11:00.1: (unregistered net_device): Failed to enable PCI sriov: -12
ixgbe 0000:11:00.1: Multiqueue Enabled: Rx Queue count = 16, Tx Queue count = 1
ixgbe 0000:11:00.1: (PCI Express:5.0GT/s:Width x8) 00:1b:21:4a:fe:99
ixgbe 0000:11:00.1: MAC: 2, PHY: 15, SFP+: 6, PBA No: E66562-003
ixgbe 0000:11:00.1: Intel(R) 10 Gigabit Network Connection
...
Expected results:
no the above messages

Additional info: