When a xenbus watch fires the event can contain some additional data as well as the path which fired and the watch token. This additional data is not passed through to userspace xenbus clients. This functionality is implemented by upstream changeset http://xenbits.xensource.com/linux-2.6.18-xen.hg?cs=8523584ffaa3. All RHEL 4 and RHEL 5 kernels have this problem.
Please state which/what userspace xenbus clients need the additional information, and how those clients work or don't work w/o the additional information currently.
Ian, any feedback on the need info request?
Sorry for not getting back to you sooner. I have attempted to contact the customer who originally made this request to me to find out what they are doing but with no luck. My impression at the time was that they had a simple message passing layer where you watch a node and when it fires you can get a bit of extra detail in the watch message itself rather than having to go to xenstore again to find out what happened, or something like that... Since the original impetus seems to have gone as far as I am concerned you are welcome to close this, or to leave it as a low priority wishlist bug.
I'm closing this for now, as it doesn't seem relevant at the moment. If the customer that needs this comes back, we can re-open this or open up a new BZ. Chris Lalancette