Intel 253666-024US User Manual
Page 464
3-418 Vol. 2A
FXSAVE—Save x87 FPU, MMX Technology, SSE, and SSE2 State
INSTRUCTION SET REFERENCE, A-M
FXSAVE—Save x87 FPU, MMX Technology, SSE, and SSE2 State
Description
Saves the current state of the x87 FPU, MMX technology, XMM, and MXCSR registers
to a 512-byte memory location specified in the destination operand. The content
layout of the 512 byte region depends on whether the processor is operating in non-
64-bit operating modes or 64-bit sub-mode of IA-32e mode. The operation of
FXSAVE in non-64-bit modes are described first.
Non-64-Bit Mode Operation
Table 3-48 shows the layout of the state information in memory when the processor
is operating in legacy modes.
Opcode
Instruction
64-Bit
Mode
Compat/
Leg Mode
Description
0F AE /0
FXSAVE m512byte
Valid
Valid
Save the x87 FPU, MMX, XMM,
and MXCSR register state to
m512byte.
Table 3-48. Non-64-bit-Mode Layout of FXSAVE and FXRSTOR
Memory Region
15
14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Rsrvd
CS
FPU IP
FOP
FTW
FSW
FCW
0
MXCSR_MASK
MXCSR
Rsrvd
DS
FPU DP
16
Reserved
ST0/MM0
32
Reserved
ST1/MM1
48
Reserved
ST2/MM2
64
Reserved
ST3/MM3
80
Reserved
ST4/MM4
96
Reserved
ST5/MM5
112
Reserved
ST6/MM6
128
Reserved
ST7/MM7
144
XMM0
160
XMM1
176
XMM2
192
XMM3
208
XMM4
224