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In the x86 architecture, the CPUID instruction (identified by a CPUID opcode) is a processor supplementary instruction (its name derived from CPU Identification) ...
CPUID model numbers are 30h-3Fh. AMD Excavator Family 15h (4th-gen) – fourth-generation Bulldozer (Final optimisation). CPUID model numbers are 60h-6Fh, later updated revisions have model numbers 70h-7Fh. AMD Zen – family of microarchitectures. The successor to Bulldozer. Included in the Ryzen and Epyc CPU lines.
CPU-Z is more comprehensive in virtually all areas compared to the tools provided in the Windows to identify various hardware components, and thus assists in identifying certain components without the need of opening the case; particularly the core revision and RAM clock rate.
The instructions below are those enabled by the BMI bit in CPUID. Intel officially considers LZCNT as part of BMI, but advertises LZCNT support using the ABM CPUID feature flag. [3] BMI1 is available in AMD's Jaguar, [5] Piledriver [6] and newer processors, and in Intel's Haswell [7] and newer processors.
Takes as input a CPUID leaf index in EAX and, depending on leaf, a sub-index in ECX. Result is returned in EAX,EBX,ECX,EDX. [d] Instruction is serializing, and causes a mandatory #VMEXIT under virtualization. Support for CPUID can be checked by toggling bit 21 of EFLAGS (EFLAGS.ID) – if this bit can be toggled, CPUID is present. Usually 3 [e]
In the model 23 (cpuid 01067xh), Intel started marketing stepping with full (6 MB) and reduced (3 MB) L2 cache at the same time, and giving them identical cpuid values. All steppings have the new SSE4.1 instructions. Stepping C1/M1 was a bug fix version of C0/M0 specifically for quad core processors and only used in those.
An x86-64 processor acts identically to an IA-32 processor when running in real mode or protected mode, which are supported modes when the processor is not in long mode.. A bit in the CPUID extended attributes field informs programs in real or protected modes if the processor can go to long mode, which allows a program to detect an x86-64 processor.
The CPUID instruction can be used on both AMD and Intel CPUs to check whether the RDRAND instruction is supported. If it is, bit 30 of the ECX register is set after calling CPUID standard function 01H. [10] AMD processors are checked for the feature using the same test. [11] RDSEED availability can be checked on Intel CPUs in a similar manner.