CPUID—CPU Identification

INSTRUCTION SET REFERENCE, A-L

Vol. 2A 3-215

INPUT EAX = 12H: Returns Intel SGX Enumeration Information

When CPUID executes with EAX set to 12H and ECX = 0H, the processor returns information about Intel SGX capa-
bilities. See Table 3-8. 
When CPUID executes with EAX set to 12H and ECX = 1H, the processor returns information about Intel SGX attri-
butes. See Table 3-8. 
When CPUID executes with EAX set to 12H and ECX = n (n > 1), the processor returns information about Intel SGX 
Enclave Page Cache. See Table 3-8.

INPUT EAX = 14H: Returns Intel Processor Trace Enumeration Information

When CPUID executes with EAX set to 14H and ECX = 0H, the processor returns information about Intel Processor 
Trace extensions. See Table 3-8. 
When CPUID executes with EAX set to 14H and ECX = n (n > 0 and less than the number of non-zero bits in 
CPUID.(EAX=14H, ECX= 0H).EAX), the processor returns information about packet generation in Intel Processor 
Trace. See Table 3-8. 

INPUT EAX = 15H: Returns Time Stamp Counter/Core Crystal Clock Information

When CPUID executes with EAX set to 15H and ECX = 0H, the processor returns information about Time Stamp 
Counter/Core Crystal Clock. See Table 3-8.

INPUT EAX = 16H: Returns Processor Frequency Information

When CPUID executes with EAX set to 16H, the processor returns information about Processor Frequency Informa-
tion. See Table 3-8. 

INPUT EAX = 17H: Returns System-On-Chip Information

When CPUID executes with EAX set to 17H, the processor returns information about the System-On-Chip Vendor 
Attribute Enumeration. See Table 3-8. 

METHODS FOR RETURNING BRANDING INFORMATION

Use the following techniques to access branding information:
1. Processor brand string method.
2. Processor brand index; this method uses a software supplied brand string table.
These two methods are discussed in the following sections. For methods that are available in early processors, see 
Section: “Identification of Earlier IA-32 Processors” in Chapter 19 of the Intel® 64 and IA-32 Architectures Soft-
ware Developer’s Manual, Volume 1.

The Processor Brand String Method

Figure 3-9 describes the algorithm used for detection of the brand string. Processor brand identification software 
should execute this algorithm on all Intel 64 and IA-32 processors. 
This method (introduced with Pentium 4 processors) returns an ASCII brand identification string and the Processor 
Base frequency of the processor to the EAX, EBX, ECX, and EDX registers.