multi-byte no ops in x86

http://www.asmpedia.org/index.php?title=NOP


90                    nop
6690                xchg    ax,ax ; 66: switch to 16-bit operand 90: opcode
0f1f00              nop     dword ptr [eax] ; 0f1f: 2-byte opcode 00: mod=00 reg=000 rm=000 [EAX]
0f1f4000           nop     dword ptr [eax] ; 0f1f: 2-byte opcode 40: mod=01 reg=000 rm=000 [EAX+0x00]
0f1f440000       nop     dword ptr [eax+eax] ; 0f1f: 2-byte opcode 44: mod=01 reg=000 rm=100 SIB + 0x00
660f1f440000    nop     word ptr [eax+eax] ; 66: switch to 16-bit operand 0f1f: 2-byte opcode 44: mod=01 reg=000 rm=100 SIB + 0x00
0f1f8000000000 nop     dword ptr [eax] ; 0f1f: 2-byte opcode 80: mod=10 reg=000 rm=000 [EAX+0x00000000]