Bug 697725

Summary: Failed enable VFs of 82576NIC on 32bits host
Product: Red Hat Enterprise Linux 5 Reporter: Yuyu Zhou <yuzhou>
Component: kernel-xenAssignee: Xen Maintainance List <xen-maint>
Status: CLOSED NOTABUG QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 5.7CC: drjones, leiwang, qwan, xen-maint
Target Milestone: rcKeywords: Regression
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-04-19 08:17:31 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description Flags
dmesg log none

Description Yuyu Zhou 2011-04-19 03:24:24 UTC
Description of problem:
Failed to enable VFs of Intel 82576 NIC on 32bits host.

Version-Release number of selected component (if applicable):
kernel-xen-2.6.18-257.el5.i686
xen-3.0.3-128.el5

How reproducible:
100%

Steps to Reproduce:
1- boot up xen host with iommu and pci_pt_e820_access enabled
   Add "iommu=1" in kernel line
   Add "pci_pt_e820_access=on" in module line
   Example:
      title Red Hat Enterprise Linux Server (2.6.18-164.9.1.el5xen)
         root (hd0,0)
         kernel /xen.gz-2.6.18-164.9.1.el5 iommu=1 loglvl=all guest_loglvl=all
         module /vmlinuz-2.6.18-164.9.1.el5xen ro root=/dev/VolGroup01/LogVol00  pci_pt_e820_access=on
         module /initrd-2.6.18-164.9.1.el5xen.img

2- Check whether PF enabled in Dom0
   Example:
   # lspci | grep 82576
   Two PF NIC should be shown

3- Reload igb (driver for intel 82576 NIC) module with max_vfs=7 parameter
   # modprobe -r igb
   # modprobe igb max_vfs=7

4- - Check whether N VFs enabled in Dom0
   # lspci | grep 82576
   Corresponding number of VFs should be shown.

Actual results:
On Step 4, only 2 PFs should be shown

Expected results:
On Step 4, 14 VFs and 2 PFs should be shown

Addition info:
It works fine with kernel-xen-2.6.18-257.el5.x86_64 for 64bits host. 
It also works fine for for kernel-xen-2.6.18-256.el5 on both 32bit and 64bit host.
Furthermore, it also works fine with bare metal kernel (kernel-2.6.18-257.el5.i686).

Comment 1 Yuyu Zhou 2011-04-19 03:25:12 UTC
Created attachment 493061 [details]
dmesg log

Comment 3 Andrew Jones 2011-04-19 06:36:48 UTC
At first glance I don't see any suspicious commits in the kernel between -256 and -257, and nothing changed in the hypervisor. Can we get the dmesg from the working 32-bit -256 kernel? Actually, it might be easier if we just get access to the machine.

Comment 4 Andrew Jones 2011-04-19 08:17:31 UTC
Diffing the dmesgs revealed a typo on the -257 command line

< Kernel command line: ro root=LABEL=/ pci_pt_e820_access=on
< pci_pt_e820_access: enabled
---
> Kernel command line: ro root=LABEL=/ pci_pt_e820=access=on

note the extra = that should be a '_' in pci_pt_e820=access=on

Correcting the typo in grub and rebooting restores the functionality.