Microsoft documentation describes the half-duplex synchronization mode as "Not Appropriate for Shipped Products". Full-duplex provides better performance and system responsiveness.
This request was evaluated by Red Hat Product Management for
inclusion in the current release of Red Hat Enterprise Linux.
Because the affected component is not scheduled to be updated in the
current release, Red Hat is unfortunately unable to address this
request at this time. Red Hat invites you to ask your support
representative to propose this request, if appropriate and relevant,
in the next release of Red Hat Enterprise Linux.
Fixed as part of xenpv-win-1.2.0-1 (distributed with RHBA-2010:0514-06).