x86 Opcode FXSAVE

Opcode FXSAVE

CPU: Pentium II (Deschutes) +
Type of Instruction: User

Instruction: FXSAVE dest

Description:
Fast Save 94 (16-bit mode) or 108 (32-bit mode) byte of
F.P. context to memory.
Format of context as in standart x86 instruction: FSAVE.

Note: Check CPUID, EAX=1, bit 24 for knew CPU support this feature.
And then look at CR4.bit9.

Format of F.P./MMX Save Area:
Offset
(hex) Size Description
+00 WORD FCW (Control word)
+02 WORD FSW (Status word)
+04 WORD FTW (Tag word)
+06 WORD FOP (lower 11-bit F.P. opcode)
+08 DWORD IP (F.P. Instruction pointer)
+0C WORD CS
+10 DWORD DP (F.P. Data pointer)
+14 WORD DS
+18 DWORD MXCSR (Pentium III+)
see LDMXCSR instruction for more info
+20 TBYTE ST0/MM0
+30 TBYTE ST1/MM1
+40 TBYTE ST2/MM2
+50 TBYTE ST3/MM3
+60 TBYTE ST4/MM4
+70 TBYTE ST5/MM5
+80 TBYTE ST6/MM6
+90 TBYTE ST7/MM7

+A0 16BYTE XMM0 (Pentium III+)
+B0 16BYTE XMM1 (Pentium III+)
+C0 16BYTE XMM2 (Pentium III+)
+D0 16BYTE XMM3 (Pentium III+)
+E0 16BYTE XMM4 (Pentium III+)
+F0 16BYTE XMM5 (Pentium III+)
+100 16BYTE XMM6 (Pentium III+)
+110 16BYTE XMM7 (Pentium III+)

All other fields are reserved.
Full length of Save/Restore area is 512 byte. (200h)

Flags Affected: None

CPU mode: any

+++++++++++++++++++++++
Physical Form & COPs:

FXSAVE mem512byte 0F AE mm000mmm

Clocks: n/a