CPUID—CPU Identification

INSTRUCTION SET REFERENCE, A-L

Vol. 2A 3-201

System-On-Chip Vendor Attribute Enumeration Sub-leaves (EAX = 17H, ECX > MaxSOCID_Index)

17H

NOTES:

Leaf 17H output depends on the initial value in ECX.

EAX

Bits 31 - 00: Reserved = 0.

EBX

Bits 31 - 00: Reserved = 0.

ECX

Bits 31 - 00: Reserved = 0.

EDX

Bits 31 - 00: Reserved = 0.

Unimplemented CPUID Leaf Functions

40000000H 

-

4FFFFFFFH

Invalid. No existing or future CPU will return processor identification or feature information if the initial 

EAX value is in the range 40000000H to 4FFFFFFFH.

Extended Function CPUID Information

80000000H EAX

Maximum Input Value for Extended Function CPUID Information.

EBX

Reserved.

ECX

Reserved.

EDX

Reserved.

80000001H EAX

Extended Processor Signature and Feature Bits.

EBX

Reserved.

ECX

Bit 00: LAHF/SAHF available in 64-bit mode.

Bits 04 - 01: Reserved.

Bit 05: LZCNT.

Bits 07 - 06: Reserved.

Bit 08: PREFETCHW.

Bits 31 - 09: Reserved.

EDX

Bits 10 - 00: Reserved.

Bit 11: SYSCALL/SYSRET available in 64-bit mode.

Bits 19 - 12: Reserved = 0.

Bit 20: Execute Disable Bit available.

Bits 25 - 21: Reserved = 0.

Bit 26: 1-GByte pages are available if 1.

Bit 27: RDTSCP and IA32_TSC_AUX are available if 1.

Bit 28: Reserved = 0.
Bit 29: Intel

®

 64 Architecture available if 1.

Bits 31 - 30: Reserved = 0.

80000002H EAX

EBX

ECX

EDX

Processor Brand String.

Processor Brand String Continued.

Processor Brand String Continued.

Processor Brand String Continued.

80000003H EAX

EBX

ECX

EDX

Processor Brand String Continued.

Processor Brand String Continued.

Processor Brand String Continued.

Processor Brand String Continued.

Table 3-8.  Information Returned by CPUID Instruction (Contd.)

Initial EAX 

Value

Information Provided about the Processor