CPUID

Article

51 sections

Contents

History
Calling CPUID
EAX=0: Highest Function Parameter and Manufacturer ID
EAX=1: Processor Info and Feature Bits
EAX=2: Cache and TLB Descriptor Information
EAX=3: Processor Serial Number
EAX=4 and EAX=8000'001Dh: Cache Hierarchy and Topology
EAX=4 and EAX=Bh: Intel Thread/Core and Cache Topology
EAX=5: MONITOR/MWAIT Features
EAX=6: Thermal and Power Management
EAX=7, ECX=0: Extended Features
EAX=7, ECX=1: Extended Features
EAX=7, ECX=2: Extended Features
EAX=0Dh: XSAVE Features and State Components
EAX=12h: SGX Capabilities
EAX=14h: Processor Trace
EAX=15h and EAX=16h: CPU, TSC, Bus and Core Crystal Clock Frequencies
EAX=17h: SoC Vendor Attribute Enumeration
EAX=19h: Intel Key Locker Features
EAX=1Dh: Intel AMX Tile Information
EAX=1Eh: Intel AMX Tile Multiplier (<code>TMUL</code>) Information
EAX=21h: Reserved for TDX enumeration
EAX=24h, ECX=0: AVX10 Converged Vector ISA
EAX=24h, ECX=1: Discrete AVX10 Features
EAX=2000'0000h: Highest Xeon Phi Function Implemented
EAX=2000'0001h: Xeon Phi Feature Bits
EAX=4000'0000h-4FFFF'FFFh: Reserved for [[Hypervisor]]s
EAX=8000'0000h: Highest Extended Function Implemented
EAX=8000'0001h: Extended Processor Info and Feature Bits
EAX=8000'0002h,8000'0003h,8000'0004h: Processor Brand String
EAX=8000'0005h: L1 Cache and TLB Identifiers
EAX=8000'0006h: Extended L2 Cache Features
EAX=8000'0007h: Processor Power Management Information and RAS Capabilities
EAX=8000'0008h: Virtual and Physical Address Sizes
EAX=8000'000Ah: SVM features
EAX=8000'001Fh: Encrypted Memory Capabilities
EAX=8000'0021h: Extended Feature Identification
EAX=8000'0025h: Encrypted Memory Capabilities 2
EAX=8C86'0000h: Hygon Extended Feature Flags
EAX=8FFF'FFFEh and EAX=8FFF'FFFFh: AMD Easter Eggs
EAX=C000'0000h: Highest [[Centaur Technology|Centaur]] Extended Function
EAX=C000'0001h: Centaur Feature Information
EAX=C000'0006h, ECX=0: Zhaoxin Feature Information
CPUID usage from high-level languages
Inline assembly
Wrapper functions
CPU-specific information outside x86
See also
References
Further reading
External links

In the x86 architecture, the CPUID instruction (identified by a CPUID opcode) is a processor supplementary instruction (its name derived from "CPU Identification") allowing software to discover details of the processor. It was introduced by Intel in 1993 with the launch of the Pentium and late 486 processors.

A program can use the CPUID to determine processor type and whether features such as MMX/SSE are implemented.