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3-164 Vol. 2A CPUID—CPU Identification
INSTRUCTION SET REFERENCE, A-M
CPUID leaves > 3 < 80000000 are visible only when
IA32_MISC_ENABLES.BOOT_NT4[bit 22] = 0 (default).
Deterministic Cache Parameters Leaf
04H NOTES:
04H output depends on the initial value in ECX.
See also: “INPUT EAX = 4: Returns Deterministic Cache Parameters
for each level on page 3-180.
EAX Bits 4-0: Cache Type Field
0 = Null - No more caches 3 = Unified Cache
1 = Data Cache 4-31 = Reserved
2 = Instruction Cache
Bits 7-5: Cache Level (starts at 1)
Bits 8: Self Initializing cache level (does not need SW initialization)
Bits 9: Fully Associative cache
Bit 10: Write-Back Invalidate/Invalidate
0 = WBINVD/INVD from threads sharing this cache acts upon lower
level caches for threads sharing this cache
1 = WBINVD/INVD is not guaranteed to act upon lower level caches
of non-originating threads sharing this cache.
Bit 11: Cache Inclusiveness
0 = Cache is not inclusive of lower cache levels.
1 = Cache is inclusive of lower cache levels.
Bits 13-12: Reserved
Bits 25-14: Maximum number of threads sharing this cache in a physi-
cal package*
Bits 31-26: Maximum number of processor cores in the physical
package* **
EBX Bits 11-00: L = System Coherency Line Size*
Bits 21-12: P = Physical Line partitions*
Bits 31-22: W = Ways of associativity*
ECX
EDX
Bits 31-00: S = Number of Sets*
Reserved = 0
NOTES:
* Add one to the return value to get the result.
** The returned value is constant for valid initial values in ECX. Valid
ECX values start from 0.
Table 3-12. Information Returned by CPUID Instruction (Contd.)
Initial EAX
Value Information Provided about the Processor