Monthly Archives: August 2009

VMWorld Challenge – Find Xen Shirt

For those of you attending the VMWorld conference next week, here is a challenge from the community manager. Can you find someone wearing this shirt:


Please take a picture with that person wearing the shirt and then send to me at I will award a prize to all participants.

Good Luck!

Backport of igb driver to linux-2.6.18-xen

From xen-devel (Simon Horman):

I am happy to announce a refreshed backport of the IGB driver to linux-2.6.18-xen.

To allow the creation of virtual functions (VF) on the 82576 that can be passed through to domUs. This back-port is successful in that regard.

The current igb driver in linux-2.6.18-xen seems to be a back-port of a driver from RHEL5 that predates anything present in Linus’s kernel tree.

This makes back-porting of changes from Linus’s tree difficult. In particular, the original commit to Linus’s tree includes multi-queue support, a non-trivial feature, whereas the code currently in linux-2.6.18-xen does not.

With this in mind the method used was to back-port the original commit made to Linus’s tree and then back-port subsequent commits to Linus’s tree.

Although somewhat verbose this method appears to have worked quite well.

Some patches were not back-ported, in particular GRO. This is because the back-port seemed to be quite difficult for little gain. I’m happy to re-consider any non-back-ported patches if there is interest.

In total there are 191 patches on top of linux-2.6.18-xen

“xen/x86: make do_settimeofday() return -EPERM when clock can’t be changed”

(930:506133327116). Apart from one patch written by myself they all correspond to patches in Linus’s kernel tree. Where the patches have been modified I have noted this in the changelog and added my own Signed-off-by line. The majority of patches are unmodified.

Due to the large number of patches I am providing this backport as an hg tree,

At this time it should be possible to pull this tree into linux-2.6.18-xen or to use it independently.

I am happy to post the patches to xen-devel if that is of value.

However my experience in the past has shown that posting more than a handful of patches results in a re-send-fest due to mangling issues.

There is also an issue that the first patch “igb: port to driver originally committed to Linus’s tree” (931:6b25a2daf6bc) is rather large at 192Kbytes.

Known Limitations

* This back-port does not include the VF driver (igbvf). This means that VFs created using the igb driver can’t be used by dom0. They can, however, be passed through to domUs.

* removing the igb module while a VF is passed-through results in a hypervisor panic. This is after several pciback messages which explain that you have done something that you sholdn’t.

pciback: ****** removing device 0000:02:10.1 while still in-use! ******

pciback: ****** driver domain may still access this device’s i/o resources!

pciback: ****** shutdown driver domain before binding device

pciback: ****** to other drivers or domains

(XEN) [VT-D]iommu.c:1271:d0 domain_context_unmap:PCIe: bdf = 2:10.1

(XEN) Xen BUG at msi.c:776

* The tree does not compile with PCI_IOV enabled between changesets

– “igb: this patch addes the sr-iov enablement option via num_vfs parameter”


– “igb: remove sysfs entry that was used to set the number of vfs”


This is because the first patch makes use of netdev->dev which does not exist. However the need for this is removed by the second patch.

IO controller Mini-Summit 2009

From xen-devel mailing list:

As I have notified before, The 1st Linux IO controller Mini-Summit will be held in Tokyo Japan on Oct 17 — day before the 9th Linux kernel summit. So I would like to propose the following topics for the mini-summit and discuss about them.
– Multiple IO controller development projects
– There are two activities for the development of IO controller,
Vivek’s io-controller and dm-ioband. Do we have to pick one of
them to put into the mainline? How to advance the development?
– Extensions of struct bio
– Make a bio point to the io_context of a process which creates the
I/O request. This allows to pass the IO scheduling class and
priority information to IO controller even if the IO is submitted
by another process which does not create the request, such as a
worker thread.
– Add a new flag to struct bio to identify the bio as urgent. This gives IO controller a chance to handle the bio as high priority.
This flag should be set if the bio is created for the page-out operation.
– I/O tracking and charging policy
– Which process, a page-requesting process or a page-returning
process, should be charged for the I/O caused by page reclaim?
We should consider two cases where the IO flushes anonymous pages
and file mapped pages.

I think this is a good opportunity to meet face-to-face to discuss about IO controller development. I would like to many developers to join this mini-summit. Please visit the following URL for more information about the mini-summit.

If you would like to join the mini-summit, please e-mail to me or post on the wiki page, (You need an account on to edit the wiki page.)

All comments, questions, suggestions and anything else are appreciated.

Ryo Tsuruta

Xen 4.0 Feature Discussion

There has been some recent blog discussions about the next feature set for the community hypervisor. The feature list at is a collection of “wants” gathered from the general community and is not a definitive roadmap. The Xen hypervisor developers monitor this list when determining what features to work on, but as with any open source project – there is no guarantee that a given feature will be developed.

Also, the plan to move the next version from 3.4 to 4.0 instead of 3.5 is based on the change of the underlying Linux kernel for Dom0.

New XCI Mailing List Available

XCI Developers:

For those of you working on the XCI project (“Xen Client Initiative”); I have created a new mailing list for developers to work from:

Registration for this new mailing list is at

NOTE: I have not setup a xci-users mailing list as the product is still in active development.

Xen Users Commonly Asked Questions Guide – UPDATED

I have taken the last 4 weeks of xen-users questions and added some of them to the always growing Xen Users Commonly Asked Questions Guide.  As always, feel free to send me new items for the guide and don’t forget to tell your friends about it; much quicker answers to common questions than asking again on the mailing lists.

Finally, don’t forget that you can always search all Xen community emails at