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Vol. 3 8-57
MULTIPLE-PROCESSOR MANAGEMENT
int DeriveCore_Mask_Offsets (void)
{
if (!HWMTSupported()) return -1;
execute cpuid with eax = 11, ECX = 0;
while( ECX[15:8] ) { // level type encoding is valid
If (returned level type encoding in ECX[15:8] matches CORE) {
Mask_Core_shift = EAX[4:0]; // needed to distinguish different physical packages
COREPlusSMT_MASK = ~( (-1) << Mask_Core_shift);
CORE_MASK = COREPlusSMT_MASK ^ SMT_MASK;
PACKAGE_MASK = (-1) << Mask_Core_shift;
return 0
}
ECX ++;
execute cpuid with eax = 11;
}
return -1;
}
c. Query the x2APIC ID of a logical processor.
APIC_IDs for each logical processor.
unsigned char Getx2APIC_ID (void)
{
unsigned reg_edx = 0;
execute cpuid with eax = 11, ECX = 0
store returned value of edx
return (unsigned) (reg_edx) ;
}
Example 8-20. Support Routines for Identifying Package, Core and Logical Processors from 8-
bit Initial APIC ID
a. Find the size of address space for logical processors in a physical processor
package.
#define NUM_LOGICAL_BITS 0x00FF0000
// Use the mask above and CPUID.1.EBX[23:16] to obtain the max number of addressable IDs
// for logical processors in a physical package,
//Returns the size of address space of logical processors in a physical processor package;
// Software should not assume the value to be a power of 2.