Intel 64 and IA-32 Architectures Software Developers Manual Volume 2A, Instruction Set Reference, A-M

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INSTRUCTION SET REFERENCE, A-M
A vendor identification string is also returned in EBX, EDX, and ECX. For Intel
processors, the string is “GenuineIntel” and is expressed:
EBX ← 756e6547h (* "Genu", with G in the low nibble of BL *)
EDX ← 49656e69h (* "ineI", with i in the low nibble of DL *)
ECX ← 6c65746eh (* "ntel", with n in the low nibble of CL *)
INPUT EAX = 80000000H: Returns CPUID’s Highest Value for Extended Processor
Information
When CPUID executes with EAX set to 0, the processor returns the highest value the
processor recognizes for returning extended processor information. The value is
returned in the EAX register (see Table 3-13) and is processor specific.
Table 3-13. Highest CPUID Source Operand for Intel 64 and IA-32 Processors
Intel 64 or IA-32 Processors
Highest Value in EAX
Basic Information Extended Function
Information
Earlier Intel486 Processors CPUID Not Implemented CPUID Not Implemented
Later Intel486 Processors and
Pentium Processors
01H Not Implemented
Pentium Pro and Pentium II
Processors, Intel
®
Celeron
®
Processors
02H Not Implemented
Pentium III Processors 03H Not Implemented
Pentium 4 Processors 02H 80000004H
Intel Xeon Processors 02H 80000004H
Pentium M Processor 02H 80000004H
Pentium 4 Processor
supporting Hyper-Threading
Technology
05H 80000008H
Pentium D Processor (8xx) 05H 80000008H
Pentium D Processor (9xx) 06H 80000008H
Intel Core Duo Processor 0AH 80000008H
Intel Xeon Processor 5100
Series
0AH 80000008H