Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 1690

WBINVD—Write-Back and Invalidate Cache (Continued)
Virtual 8086 Mode Exceptions
#GP(0)
Intel Architecture Compatibility
The WDINVD instruction implementation-dependent; its function may be implemented
differently on future Intel architecture processors. The instruction is not supported on
Intel architecture processors earlier than the Intel486 processor.
4:388
The WBINVD instruction cannot be executed at the virtual 8086
mode.
Volume 4: Base IA-32 Instruction Reference