A.5.320 UD0, UD1, UD2: Undefined Instruction
UD0 ; 0F FF [186,UNDOC]
UD1 ; 0F B9 [186,UNDOC]
UD2 ; 0F 0B [186]
UDx can be used to generate an invalid opcode exception, for testing
purposes.
UD0 is specifically documented by AMD as being reserved for this
purpose.
UD1 is documented by Intel as being available for this purpose.
UD2 is specifically documented by Intel as being reserved for this
purpose. Intel document this as the preferred method of generating an
invalid opcode exception.
All these opcodes can be used to generate invalid opcode exceptions on
all currently available processors.