Thanks to Bart Van Assche the valgrind patches to support Xen privcmd ioctls which I posted previously have now been committed to the Valgrind trunk branch (which will eventually become 3.9.0). Unlike the previous iteration of the patches posted to the list what is no in tree do not require building against a specific set of Xen headers. The code currently supports Xen 4.1, 4.2 and unstable versions of the interfaces used by xl domain create and select other toolstack operations. I will fault in additional hypercalls and versions on demand so please report them here if you see messages such as "WARNING: unhandled hypercall" or "WARNING: unhandled XXX subop". You can find the code in svn://svn.valgrind.org/valgrind/trunk revision 1308 onwards. Cheers, Ian.