Intel® Architecture Instruction Set Extensions Programming Reference

INPUT EAX = 1: Returns Additional Information in EBX
APPLICATION PROGRAMMING MODEL
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.
• Local APIC ID (high byte of EBX) — this number is the 8-bit ID that is assigned to the local APIC on the
processor during power up. This field was introduced in the Pentium 4 processor.
INPUT EAX = 1: Returns Feature Information in ECX and EDX
When CPUID executes with EAX set to 1, feature information is returned in ECX and EDX.
• Figure 2-3 and Table 2-26 show encodings for ECX.
• Figure 2-4 and Table 2-27 show encodings for EDX.
For all feature flags, a 1 indicates that the feature is supported. Use Intel to properly interpret feature flags.
NOTE
Software must confirm that a processor feature is present using feature flags returned by CPUID
prior to using the feature. Software should not depend on future offerings retaining all features.
ECX
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
RDRAND
F16C
AVX
OSXSAVE
XSAVE
AES
TSC-Deadline
POPCNT
MOVBE
x2APIC
SSE4_2 — SSE4.2
SSE4_1 — SSE4.1
DCA — Direct Cache Access
PCID — Process-context Identifiers
PDCM — Perf/Debug Capability MSR
xTPR Update Control
CMPXCHG16B
FMA — Fused Multiply Add
CNXT-ID — L1 Context ID
SSSE3 — SSSE3 Extensions
TM2 — Thermal Monitor 2
EST — Enhanced Intel SpeedStep® Technology
SMX — Safer Mode Extensions
VMX — Virtual Machine Extensions
DS-CPL — CPL Qualified Debug Store
MONITOR — MONITOR/MWAIT
DTES64 — 64-bit DS Area
PCLMULQDQ — Carryless Multiplication
SSE3 — SSE3 Extensions
Reserved
0
Figure 2-3. Feature Information Returned in the ECX Register
OM16524b
Ref. # 319433-014 2-37
9
8
7
6
5
4
3
2
1
0