Intel® Processor Identification and the CPUID Instruction Application Note
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Intel® Processor Identification and the CPUID Instruction Application Note 485 May 2012 Order Number: 241618-039 INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH INTEL® PRODUCTS. NO LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. EXCEPT AS PROVIDED IN INTEL'S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, INTEL ASSUMES NO LIABILITY WHATSOEVER, AND INTEL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO SALE AND/OR USE OF INTEL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. Intel products are not intended for use in medical, life saving, life sustaining, critical control or safety systems, or in nuclear facility applications. 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All rights reserved. * Other brands and names may be claimed as the property of others. 2 Application Note Contents 1Introduction............................................................................................................ 11 1.1 Update Support................................................................................................. 12 1.2 Reference Documents ........................................................................................ 12 2 Usage Guidelines ..................................................................................................... 13 3 Detecting the CPUID Instruction ............................................................................. 15 4 Proper Identification Sequence ............................................................................... 17 5 Output of the CPUID Instruction.............................................................................. 19 5.1 Standard CPUID Functions.................................................................................. 21 5.1.1 Vendor-ID and Largest Standard Function (Function 0)................................ 21 5.1.2 Feature Information (Function 01h) .......................................................... 21 5.1.3 Cache Descriptors (Function 02h) ............................................................. 33 5.1.4 Processor Serial Number (Function 03h) .................................................... 37 5.1.5 Deterministic Cache Parameters (Function 04h).......................................... 37 5.1.6 MONITOR / MWAIT Parameters (Function 05h)........................................... 39 5.1.7 Digital Thermal Sensor and Power Management Parameters (Function 06h) ... 39 5.1.8 Structured Extended Feature Flags Enumeration (Function 07h) ................... 40 5.1.9 Reserved (Function 08h) ......................................................................... 40 5.1.10 Direct Cache Access (DCA) Parameters (Function 09h) ................................ 41 5.1.11 Architectural Performance Monitor Features (Function 0Ah).......................... 41 5.1.12 x2APIC Features / Processor Topology (Function 0Bh) ................................. 41 5.1.13 Reserved (Function 0Ch) ......................................................................... 43 5.1.14 XSAVE Features (Function 0Dh) ............................................................... 44 5.2 Extended CPUID Functions ................................................................................. 44 5.2.1 Largest Extended Function # (Function 80000000h) ................................... 44 5.2.2 Extended Feature Bits (Function 80000001h) ............................................. 45 5.2.3 Processor Brand String (Function 80000002h, 80000003h, 80000004h) ........ 46 5.2.4 Reserved (Function 80000005h)............................................................... 47 5.2.5 Extended L2 Cache Features (Function 80000006h) .................................... 48 5.2.6 Advanced Power Management (Function 80000007h) .................................. 48 5.2.7 Virtual and Physical Address Sizes (Function 80000008h) ............................ 49 6 Processor Serial Number ......................................................................................... 51 6.1 Presence of Processor Serial Number ................................................................... 51 6.2 Forming the 96-bit Processor Serial Number ......................................................... 52 7 Brand ID and Brand String....................................................................................... 53 7.1 Brand ID .......................................................................................................... 53 7.2 Brand String..................................................................................................... 54 8 Denormals Are Zero................................................................................................. 55 9 Operating Frequency ............................................................................................... 57 10 Program Examples .................................................................................................. 59 Application Note 3 Figures 3-1 Flag Register Evolution .......................................................................................15 4-1 Flow of Processor get_cpu_type Procedure ............................................................18 5-1 CPUID Instruction Outputs ..................................................................................20 5-2 EDX Register After RESET ...................................................................................22 5-3 Processor Signature Format on Intel386™ Processors .............................................23 5-4 L2 Cache Details................................................................................................48 10-1 Flow of Processor Identification Extraction Procedure ..............................................59 10-2 Flow of Processor Frequency Calculation Procedure.................................................60 Tables 5-1 CPUID Feature Information .................................................................................21 5-2 Processor Type (Bit Positions 13 and 12)...............................................................22 5-3 Intel386™ Processor Signatures ..........................................................................23 5-4 Intel486™ and Subsequent Processor Signatures ...................................................23 5-5 Feature Flags Reported in the ECX Register ...........................................................29 5-6 Feature Flags Reported in the EDX Register...........................................................31 5-7 Descriptor Formats ............................................................................................33 5-8 Cache and TLB Descriptor Decode Values ..............................................................33 5-9 Intel® Core™ i7 Processor, Model 1Ah with 8-MB L3 Cache CPUID (EAX=2) ..............36 5-10 Deterministic Cache Parameters ..........................................................................37