It's a usermode header for users of /dev/xen/evtchn.
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
[corresponds to b60e48cec12f in git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>