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

3-170 Vol. 2
INSTRUCTION SET REFERENCE, A-M
NOTE
See AP-485, Intel Processor Identification and the CPUID Instruction
(Order Number 241618) and Chapter 14 in the Intel® 64 and IA-32
Architectures Software Developer’s Manual, Volume 1, for
information on identifying earlier IA-32 processors.
The Extended Family ID needs to be examined only when the Family ID is 0FH. Inte-
grate the fields into a display using the following rule:
IF Family_ID
≠ 0FH
THEN Displayed_Family = Family_ID;
ELSE Displayed_Family = Extended_Family_ID + Family_ID;
(* Right justify and zero-extend 4-bit field. *)
FI;
(* Show Display_Family as HEX field. *)
The Extended Model ID needs to be examined only when the Family ID is 06H or 0FH.
Integrate the field into a display using the following rule:
IF (Family_ID = 06H or Family_ID = 0FH)
THEN Displayed_Model = (Extended_Model_ID << 4) + Model_ID;
(* Right justify and zero-extend Extended_Model_ID and Model_ID. *)
ELSE Displayed_Model = Model_ID;
FI;
(* Show Display_Model as HEX field. *)
INPUT EAX = 1: Returns Additional Information in EBX
When CPUID executes with EAX set to 1, additional information is returned to the
EBX register:
• Brand index (low byte of EBX) — this number provides an entry into a brand
string table that contains brand strings for IA-32 processors. More information
about this field is provided later in this section.
• CLFLUSH instruction cache line size (second byte of EBX) — this number
indicates the size of the cache line flushed with CLFLUSH instruction in 8-byte
increments. This field was introduced in the Pentium 4 processor.
Table 3-14. Processor Type Field
Type Encoding
Original OEM Processor 00B
Intel OverDrive
®
Processor 01B
Dual processor (not applicable to Intel486
processors)
10B
Intel reserved 11B