Specification Sheet
Intel
®
 Xeon
®
 Processor E5-1600/E5-2600/E5-4600 v2 Product Families 63
Datasheet Volume One of Two
Interfaces
Description: Returns the data maintained in the processor IA MSR space as specified 
by the ‘Processor ID’ and ‘MSR Address’ fields. The Read Length dictates the desired 
data return size. This command supports only qword responses. All command 
responses are prepended with a completion code that contains additional pass/fail 
status information. Refer to Section 2.5.5.2 for details regarding completion codes.
2.5.2.7.2 Processor ID Enumeration
The ‘Processor ID’ field that is used to address the IA MSR space refers to a specific 
logical processor wit
hin the CPU. The ‘Processor ID’ always refers to the same physical 
location in the processor regardless of configuration as shown in the example in 
Figure 2-42. For example, if certain logical processors are disabled by BIOS, the 
Processor ID mapping will not change. The total number of Processor IDs on a CPU is 
product-specific. 
‘Processor ID’ enumeration involves discovering the logical processors enabled within 
the CPU package. This can be accomplished by reading the ‘Max Thread ID’ value 
through the RdPkgConfig() command (Index 0, Parameter 3) described in 
Section 2.5.2.6.12 and subsequently querying each of the supported processor 
threads. Unavailable processor threads will return a completion code of 0x90.
Alternatively, this information may be obtained from the RESOLVED_CORES_MASK 
register readable through the RdPCIConfigLocal() PECI command described in 
Section 2.5.2.9 or other means. Bits [7:0] and [9:8] of this register contain the ‘Core 
Mask’ and ‘Thread Mask’ information respectively. The ‘Thread Mask’ applies to all the 
enabled cores within the processor package as indicated by the ‘Core Mask’. For  
the processor PECI clients, the ‘Processor ID’ may take on values in the range 0 
through 23.
Figure 2-42. Processor ID Construction Example
T0T1T0T1T0T1T0T1T0T1T0T1T0T1T0T1
C0C1C2C3…………………C10C11C12
0123456………………181920212223
Processor 
ID (0...23)
Cores 0,1,2...12
Thread (0,1) Mask for Core10
7










