CPUID — CPU Identification
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CPUID— CPU Identification
https://www.felixcloutier.com/x86/cpuid
目录
Instruction Operand Encoding ¶
INPUT EAX = 80000000H: Returns CPUID’s Highest Value for Extended Processor Information ¶
IA32_BIOS_SIGN_ID Returns Microcode Update Signature ¶
INPUT EAX = 01H: Returns Model, Family, Stepping Information ¶
INPUT EAX = 01H: Returns Additional Information in EBX ¶
INPUT EAX = 01H: Returns Feature Information in ECX and EDX ¶
INPUT EAX = 02H: TLB/Cache/Prefetch Information Returned in EAX, EBX, ECX, EDX ¶
Example 3-1. Example of Cache and TLB Interpretation ¶
INPUT EAX = 04H: Returns Deterministic Cache Parameters for Each Level ¶
INPUT EAX = 05H: Returns MONITOR and MWAIT Features ¶
INPUT EAX = 06H: Returns Thermal and Power Management Features ¶
INPUT EAX = 07H: Returns Structured Extended Feature Enumeration Information ¶
INPUT EAX = 09H: Returns Direct Cache Access Information ¶
INPUT EAX = 0AH: Returns Architectural Performance Monitoring Features ¶
INPUT EAX = 0BH: Returns Extended Topology Information ¶
INPUT EAX = 0DH: Returns Processor Extended States Enumeration Information ¶
INPUT EAX = 12H: Returns Intel SGX Enumeration Information ¶
INPUT EAX = 14H: Returns Intel Processor Trace Enumeration Information ¶
INPUT EAX = 15H: Returns Time Stamp Counter and Nominal Core Crystal Clock Information ¶
INPUT EAX = 16H: Returns Processor Frequency Information ¶
INPUT EAX = 17H: Returns System-On-Chip Information ¶
INPUT EAX = 18H: Returns Deterministic Address Translation Parameters Information ¶
INPUT EAX = 1FH: Returns V2 Extended Topology Information ¶
METHODS FOR RETURNING BRANDING INFORMATION ¶
The Processor Brand String Method ¶
Extracting the Processor Frequency from Brand Strings ¶
The Processor Brand Index Method ¶
IA-32 Architecture Compatibility ¶
Exceptions (All Operating Modes) ¶
CPUID — CPU Identification
| Opcode | Instruction | Op/En | 64-Bit Mode | Compat/Leg Mode | Description |
|---|---|---|---|---|---|
| 0F A2 | CPUID | ZO | Valid | Valid | Returns processor identification and feature information to the EAX, EBX, ECX, and EDX registers, as determined by input entered in EAX (in some cases, ECX as well). |
Instruction Operand Encoding ¶
| Op/En | Operand 1 | Operand 2 | Operand 3 | Operand 4 |
| ZO | NA | NA | NA | NA |
Description ¶
The ID flag (bit 21) in the EFLAGS register indicates support for the CPUID instruction. If a software procedure can set and clear this flag, the processor executing the procedure supports the CPUID instruction. This instruction operates the same in non-64-bit modes and 64-bit mode.
CPUID returns processor identification and feature information in the EAX, EBX, ECX, and EDX registers.1 The instruction’s output is dependent on the contents of the EAX register upon execution (in some cases, ECX as well). For example, the following pseudocode loads EAX with 00H and causes CPUID to return a Maximum Return Value and the Vendor Identification String in the appropriate registers:
MOV EAX, 00H
CPUID
Table 3-8 shows information returned, depending on the initial value loaded into the EAX register.
Two types of information are returned: basic and extended function information. If a value entered for CPUID.EAX is higher than the maximum input value for basic or extended function for that processor then the data for the highest basic information leaf is returned. For example, using some Intel processors, the following is true:
CPUID.EAX = 05H (* Returns MONITOR/MWAIT leaf. *)
CPUID.EAX = 0AH (* Returns Architectural Performance Monitoring leaf. *) CPUID.EAX = 0BH (* Returns Extended Topology Enumeration leaf. *)2 CPUID.EAX =1FH (* Returns V2 Extended Topology Enumeration leaf. *)2
1. On Intel 64 processors, CPUID clears the high 32 bits of the RAX/RBX/RCX/RDX registers in all modes.
2. CPUID leaf 1FH is a preferred superset to leaf 0BH. Intel recommends first checking for the existence of CPUID leaf 1FH before using leaf 0BH.
CPUID.EAX = 80000008H (* Returns linear/physical address size data. *)
CPUID.EAX = 8000000AH (* INVALID: Returns same information as CPUID.EAX = 0BH. *)
If a value entered for CPUID.EAX is less than or equal to the maximum input value and the leaf is not supported on that processor then 0 is returned in all the registers.
When CPUID returns the highest basic leaf information as a result of an invalid input EAX value, any dependence on input ECX value in the basic leaf is honored.
CPUID can be executed at any privilege level to serialize instruction execution. Serializing instruction execution guarantees that any modifications to flags, registers, and memory for previous instructions are completed before the next instruction is fetched and executed.
See also:
“Serializing Instructions” in Chapter 8, “Multiple-Processor Management,” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3A.
“Caching Translation Information” in Chapter 4, “Paging,” in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3A.
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| Basic CPUID Information | |
| 0H | EAX Maximum Input Value for Basic CPUID Information. EBX “Genu” ECX “ntel” EDX “ineI” |
| 01H | EAX Version Information: Type, Family, Model, and Stepping ID (see Figure 3-6). EBX Bits 07 - 00: Brand Index. Bits 15 - 08: CLFLUSH line size (Value ∗ 8 = cache line size in bytes; used also by CLFLUSHOPT). Bits 23 - 16: Maximum number of addressable IDs for logical processors in this physical package*. Bits 31 - 24: Initial APIC ID**. ECX Feature Information (see Figure 3-7 and Table 3-10). EDX Feature Information (see Figure 3-8 and Table 3-11). NOTES: * Thenearestpower-of-2integerthatisnotsmallerthanEBX[23:16]isthenumberofuniqueinitialAPIC IDs reserved for addressing different logical processors in a physical package. This field is only valid if CPUID.1.EDX.HTT[bit 28]= 1. ** The 8-bit initial APIC ID in EBX[31:24] is replaced by the 32-bit x2APIC ID, available in Leaf 0BH and Leaf 1FH. |
| 02H | EAX Cache and TLB Information (see Table 3-12). EBX Cache and TLB Information. ECX Cache and TLB Information. EDX Cache and TLB Information. |
| 03H | EAX Reserved. EBX Reserved. ECX Bits 00 - 31 of 96 bit processor serial number. (Available in Pentium III processor only; otherwise, the value in this register is reserved.) EDX Bits 32 - 63 of 96 bit processor serial number. (Available in Pentium III processor only; otherwise, the value in this register is reserved.) NOTES: Processor serial number (PSN) is not supported in the Pentium 4 processor or later. On all models, use the PSN flag (returned using CPUID) to check for PSN support before accessing the feature. |
| CPUID leaves above 2 and below 80000000H are visible only when IA32_MISC_ENABLE[bit 22] has its default value of 0. | |
| Deterministic Cache Parameters Leaf | |
| 04H | NOTES: Leaf 04H output depends on the initial value in ECX.* See also: “INPUT EAX = 04H: Returns Deterministic Cache Parameters for Each Level” on page 221. EAX Bits 04 - 00: Cache Type Field. 0 = Null - No more caches. 1 = Data Cache. 2 = Instruction Cache. 3 = Unified Cache. 4-31 = Reserved. |
| Bits 07 - 05: Cache Level (starts at 1). Bit 08: Self Initializing cache level (does not need SW initialization). Bit 09: Fully Associative cache. Bits 13 - 10: Reserved. Bits 25 - 14: Maximum number of addressable IDs for logical processors sharing this cache**, ***. Bits 31 - 26: Maximum number of addressable IDs for 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 Bits 31-00: S = Number of Sets**. EDX Bit 00: 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 01: Cache Inclusiveness. 0 = Cache is not inclusive of lower cache levels. 1 = Cache is inclusive of lower cache levels. Bit 02: Complex Cache Indexing. 0 = Direct mapped cache. 1 = A complex function is used to index the cache, potentially using all address bits. Bits 31 - 03: Reserved = 0. NOTES: * If ECX contains an invalid sub leaf index, EAX/EBX/ECX/EDX return 0. Sub-leaf index n+1 is invalid if sub-leaf n returns EAX[4:0] as 0. ** Add one to the return value to get the result. ***The nearest power-of-2 integer that is not smaller than (1 + EAX[25:14]) is the number of unique initial APIC IDs reserved for addressing different logical processors sharing this cache. **** The nearest power-of-2 integer that is not smaller than (1 + EAX[31:26]) is the number of unique Core_IDs reserved for addressing different processor cores in a physical package. Core ID is a subset of bits of the initial APIC ID. ***** The returned value is constant for valid initial values in ECX. Valid ECX values start from 0. | |
| MONITOR/MWAIT Leaf | |
| 05H | EAX Bits 15 - 00: Smallest monitor-line size in bytes (default is processor's monitor granularity). Bits 31 - 16: Reserved = 0. EBX Bits 15 - 00: Largest monitor-line size in bytes (default is processor's monitor granularity). Bits 31 - 16: Reserved = 0. ECX Bit 00: Enumeration of Monitor-Mwait extensions (beyond EAX and EBX registers) supported. Bit 01: Supports treating interrupts as break-event for MWAIT, even when interrupts disabled. Bits 31 - 02: Reserved. |
Table 3-8. Information Returned by CPUID Instruction
| Initial EAX Value | Information Provided about the Processor |
| EDX Bits 03 - 00: Number of C0* sub C-states supported using MWAIT. Bits 07 - 04: Number of C1* sub C-states supported using MWAIT. Bits 11 - 08: Number of C2* sub C-states supported using MWAIT. Bits 15 - 12: Number of C3* sub C-states supported using MWAIT. Bits 19 - 16: Number of C4* sub C-states supported using MWAIT. Bits 23 - 20: Number of C5* sub C-states supported using MWAIT. Bits 27 - 24: Number of C6* sub C-states supported using MWAIT. Bits 31 - 28: Number of C7* sub C-states supported using MWAIT. NOTE: * ThedefinitionofC0throughC7statesforMWAITextensionareprocessor-specificC-states,notACPIC-states. | |
| Thermal and Power Management Leaf | |
| 06H | EAX Bit 00: Digital temperature sensor is supported if set. Bit 01: Intel Turbo Boost Technology available (see description of IA32_MISC_ENABLE[38]). Bit 02: ARAT. APIC-Timer-always-running feature is supported if set. Bit 03: Reserved. Bit 04: PLN. Power limit notification controls are supported if set. Bit 05: ECMD. Clock modulation duty cycle extension is supported if set. Bit 06: PTM. Package thermal management is supported if set. Bit 07: HWP. HWP base registers (IA32_PM_ENABLE[bit 0], IA32_HWP_CAPABILITIES, IA32_HWP_REQUEST, IA32_HWP_STATUS) are supported if set. Bit 08: HWP_Notification. IA32_HWP_INTERRUPT MSR is supported if set. Bit 09: HWP_Activity_Window. IA32_HWP_REQUEST[bits 41:32] is supported if set. Bit 10: HWP_Energy_Performance_Preference. IA32_HWP_REQUEST[bits 31:24] is supported if set. Bit 11: HWP_Package_Level_Request. IA32_HWP_REQUEST_PKG MSR is supported if set. Bit 12: Reserved. Bit 13: HDC. HDC base registers IA32_PKG_HDC_CTL, IA32_PM_CTL1, IA32_THREAD_STALL MSRs are supported if set. Bit 14: Intel® Turbo Boost Max Technology 3.0 available. Bit 15: HWP Capabilities. Highest Performance change is supported if set. Bit 16: HWP PECI override is supported if set. Bit 17: Flexible HWP is supported if set. Bit 18: Fast access mode for the IA32_HWP_REQUEST MSR is supported if set. Bit 19: Reserved. Bit 20: Ignoring Idle Logical Processor HWP request is supported if set. Bits 31 - 21: Reserved. EBX Bits 03 - 00: Number of Interrupt Thresholds in Digital Thermal Sensor. Bits 31 - 04: Reserved. ECX Bit 00: Hardware Coordination Feedback Capability (Presence of IA32_MPERF and IA32_APERF). The capability to provide a measure of delivered processor performance (since last reset of the counters), as a percentage of the expected processor performance when running at the TSC frequency. Bits 02 - 01: Reserved = 0. Bit 03: The processor supports performance-energy bias preference if CPUID.06H:ECX.SETBH[bit 3] is set and it also implies the presence of a new architectural MSR called IA32_ENERGY_PERF_BIAS (1B0H). Bits 31 - 04: Reserved = 0. EDX Reserved = 0. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| Structured Extended Feature Flags Enumeration Leaf (Output depends on ECX input value) | |
| 07H | Sub-leaf 0 (Input ECX = 0). * EAX Bits 31 - 00: Reports the maximum input value for supported leaf 7 sub-leaves. EBX Bit 00: FSGSBASE. Supports RDFSBASE/RDGSBASE/WRFSBASE/WRGSBASE if 1. Bit 01: IA32_TSC_ADJUST MSR is supported if 1. Bit 02: SGX. Supports Intel® Software Guard Extensions (Intel® SGX Extensions) if 1. Bit 03: BMI1. Bit 04: HLE. Bit 05: AVX2. Bit 06: FDP_EXCPTN_ONLY. x87 FPU Data Pointer updated only on x87 exceptions if 1. Bit 07: SMEP. Supports Supervisor-Mode Execution Prevention if 1. Bit 08: BMI2. Bit 09: Supports Enhanced REP MOVSB/STOSB if 1. Bit 10: INVPCID. If 1, supports INVPCID instruction for system software that manages process-context identifiers. Bit 11: RTM. Bit 12: RDT-M. Supports Intel® Resource Director Technology (Intel® RDT) Monitoring capability if 1. Bit 13: Deprecates FPU CS and FPU DS values if 1. Bit 14: MPX. Supports Intel® Memory Protection Extensions if 1. Bit 15: RDT-A. Supports Intel® Resource Director Technology (Intel® RDT) Allocation capability if 1. Bit 16: AVX512F. Bit 17: AVX512DQ. Bit 18: RDSEED. Bit 19: ADX. Bit 20: SMAP. Supports Supervisor-Mode Access Prevention (and the CLAC/STAC instructions) if 1. Bit 21: AVX512_IFMA. Bit 22: Reserved. Bit 23: CLFLUSHOPT. Bit 24: CLWB. Bit 25: Intel Processor Trace. Bit 26: AVX512PF. (Intel® Xeon PhiTM only.) Bit 27: AVX512ER. (Intel® Xeon PhiTM only.) Bit 28: AVX512CD. Bit 29: SHA. supports Intel® Secure Hash Algorithm Extensions (Intel® SHA Extensions) if 1. Bit 30: AVX512BW. Bit 31: AVX512VL. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| ECX Bit 00: PREFETCHWT1. (Intel® Xeon PhiTM only.) Bit 01: AVX512_VBMI. Bit 02: UMIP. Supports user-mode instruction prevention if 1. Bit 03: PKU. Supports protection keys for user-mode pages if 1. Bit 04: OSPKE. If 1, OS has set CR4.PKE to enable protection keys (and the RDPKRU/WRPKRU instructions). Bit 05: WAITPKG Bit 07 - 06: Reserved Bit 08: GFNI Bits 13 - 09: Reserved. Bit 14: AVX512_VPOPCNTDQ. (Intel® Xeon PhiTM only.) Bits 16 - 15: Reserved. Bits 21 - 17: The value of MAWAU used by the BNDLDX and BNDSTX instructions in 64-bit mode. Bit 22: RDPID and IA32_TSC_AUX are available if 1. Bits 24 - 23: Reserved. Bit 25: CLDEMOTE. Supports cache line demote if 1. Bit 26: Reserved Bit 27: MOVDIRI. Supports MOVDIRI if 1. Bit 28: MOVDIR64B. Supports MOVDIR64B if 1. Bit 29: Reserved Bit 30: SGX_LC. Supports SGX Launch Configuration if 1. Bit 31: Reserved. EDX Bit 01: Reserved. Bit 02: AVX512_4VNNIW. (Intel® Xeon PhiTM only.) Bit 03: AVX512_4FMAPS. (Intel® Xeon PhiTM only.) Bits 25-04: Reserved. Bit 26: Enumerates support for indirect branch restricted speculation (IBRS) and the indirect branch predictor barrier (IBPB). Processors that set this bit support the IA32_SPEC_CTRL MSR and the IA32_PRED_CMD MSR. They allow software to set IA32_SPEC_CTRL[0] (IBRS) and IA32_PRED_CMD[0] (IBPB). Bit 27: Enumerates support for single thread indirect branch predictors (STIBP). Processors that set this bit support the IA32_SPEC_CTRL MSR. They allow software to set IA32_SPEC_CTRL[1] (STIBP). Bit 28: Enumerates support for L1D_FLUSH. Processors that set this bit support the IA32_FLUSH_CMD MSR. They allow software to set IA32_FLUSH_CMD[0] (L1D_FLUSH). Bit 29: Enumerates support for the IA32_ARCH_CAPABILITIES MSR. Bit 30: Enumerates support for the IA32_CORE_CAPABILITIES MSR. Bit 31: Enumerates support for Speculative Store Bypass Disable (SSBD). Processors that set this bit support the IA32_SPEC_CTRL MSR. They allow software to set IA32_SPEC_CTRL[2] (SSBD). NOTE: * If ECX contains an invalid sub-leaf index, EAX/EBX/ECX/EDX return 0. Sub-leaf index n is invalid if n exceeds the value that sub-leaf 0 returns in EAX. | |
| Direct Cache Access Information Leaf | |
| 09H | EAX Value of bits [31:0] of IA32_PLATFORM_DCA_CAP MSR (address 1F8H). EBX Reserved. ECX Reserved. EDX Reserved. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| Architectural Performance Monitoring Leaf | |
| 0AH | EAX Bits 07 - 00: Version ID of architectural performance monitoring. Bits 15 - 08: Number of general-purpose performance monitoring counter per logical processor. Bits 23 - 16: Bit width of general-purpose, performance monitoring counter. Bits 31 - 24: Length of EBX bit vector to enumerate architectural performance monitoring events. EBX Bit 00: Core cycle event not available if 1. Bit 01: Instruction retired event not available if 1. Bit 02: Reference cycles event not available if 1. Bit 03: Last-level cache reference event not available if 1. Bit 04: Last-level cache misses event not available if 1. Bit 05: Branch instruction retired event not available if 1. Bit 06: Branch mispredict retired event not available if 1. Bits 31 - 07: Reserved = 0. ECX Reserved = 0. EDX Bits 04 - 00: Number of fixed-function performance counters (if Version ID > 1). Bits 12 - 05: Bit width of fixed-function performance counters (if Version ID > 1). Bits 14 - 13: Reserved = 0. Bit 15: AnyThread deprecation. Bits 31 - 16: Reserved = 0. |
| Extended Topology Enumeration Leaf | |
| 0BH | NOTES: CPUID leaf 1FH is a preferred superset to leaf 0BH. Intel recommends first checking for the existence of Leaf 1FH before using leaf 0BH. Most of Leaf 0BH output depends on the initial value in ECX. The EDX output of leaf 0BH is always valid and does not vary with input value in ECX. Output value in ECX[7:0] always equals input value in ECX[7:0]. Sub-leaf index 0 enumerates SMT level. Each subsequent higher sub-leaf index enumerates a higher-level topological entity in hierarchical order. For sub-leaves that return an invalid level-type of 0 in ECX[15:8]; EAX and EBX will return 0. If an input value n in ECX returns the invalid level-type of 0 in ECX[15:8], other input values with ECX > n also return 0 in ECX[15:8]. EAX Bits 04 - 00: Number of bits to shift right on x2APIC ID to get a unique topology ID of the next level type*. All logical processors with the same next level ID share current level. Bits 31 - 05: Reserved. EBX Bits 15 - 00: Number of logical processors at this level type. The number reflects configuration as shipped by Intel**. Bits 31- 16: Reserved. ECX Bits 07 - 00: Level number. Same value in ECX input. Bits 15 - 08: Level type***. Bits 31 - 16: Reserved. EDX Bits 31- 00: x2APIC ID the current logical processor. NOTES: * Software should use this field (EAX[4:0]) to enumerate processor topology of the system. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| ** Software must not use EBX[15:0] to enumerate processor topology of the system. This value in this field (EBX[15:0]) is only intended for display/diagnostic purposes. The actual number of logical processors available to Bios/OS/Applications may be different from the value of EBX[15:0], depending on software and platform hardware configurations. *** The value of the “level type” field is not related to level numbers in any way, higher “level type” values do not mean higher levels. Level type field has the following encoding: 0: Invalid. 1: SMT. 2: Core. 3-255: Reserved. | |
| Processor Extended State Enumeration Main Leaf (EAX = 0DH, ECX = 0) | |
| 0DH | NOTES: Leaf 0DH main leaf (ECX = 0). EAX Bits 31 - 00: Reports the supported bits of the lower 32 bits of XCR0. XCR0[n] can be set to 1 only if EAX[n] is 1. Bit 00: x87 state. Bit 01: SSE state. Bit 02: AVX state. Bits 04 - 03: MPX state. Bits 07 - 05: AVX-512 state. Bit 08: Used for IA32_XSS. Bit 09: PKRU state. Bits 12 - 10: Reserved. Bit 13: Used for IA32_XSS. Bits 31 - 14: Reserved. EBX Bits 31 - 00: Maximum size (bytes, from the beginning of the XSAVE/XRSTOR save area) required by enabled features in XCR0. May be different than ECX if some features at the end of the XSAVE save area are not enabled. ECX Bit 31 - 00: Maximum size (bytes, from the beginning of the XSAVE/XRSTOR save area) of the XSAVE/XRSTOR save area required by all supported features in the processor, i.e., all the valid bit fields in XCR0. EDX Bit 31 - 00: Reports the supported bits of the upper 32 bits of XCR0. XCR0[n+32] can be set to 1 only if EDX[n] is 1. Bits 31 - 00: Reserved. |
| Processor Extended State Enumeration Sub-leaf (EAX = 0DH, ECX = 1) | |
| 0DH | EAX Bit 00: XSAVEOPT is available. Bit 01: Supports XSAVEC and the compacted form of XRSTOR if set. Bit 02: Supports XGETBV with ECX = 1 if set. Bit 03: Supports XSAVES/XRSTORS and IA32_XSS if set. Bits 31 - 04: Reserved. EBX Bits 31 - 00: The size in bytes of the XSAVE area containing all states enabled by XCRO | IA32_XSS. ECX Bits 31 - 00: Reports the supported bits of the lower 32 bits of the IA32_XSS MSR. IA32_XSS[n] can be set to 1 only if ECX[n] is 1. Bits 07 - 00: Used for XCR0. Bit 08: PT state. Bit 09: Used for XCR0. Bits 12 - 10: Reserved. Bit 13: HWP state. Bits 31 - 14: Reserved. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| EDX Bits 31 - 00: Reports the supported bits of the upper 32 bits of the IA32_XSS MSR. IA32_XSS[n+32] can be set to 1 only if EDX[n] is 1. Bits 31 - 00: Reserved. | |
| Processor Extended State Enumeration Sub-leaves (EAX = 0DH, ECX = n, n > 1) | |
| 0DH | NOTES: Leaf 0DH output depends on the initial value in ECX. Each sub-leaf index (starting at position 2) is supported if it corresponds to a supported bit in either the XCR0 register or the IA32_XSS MSR. * If ECX contains an invalid sub-leaf index, EAX/EBX/ECX/EDX return 0. Sub-leaf n (0 ≤ n ≤ 31) is invalid if sub-leaf 0 returns 0 in EAX[n] and sub-leaf 1 returns 0 in ECX[n]. Sub-leaf n (32 ≤ n ≤ 63) is invalid if sub-leaf 0 returns 0 in EDX[n-32] and sub-leaf 1 returns 0 in EDX[n-32]. EAX Bits 31 - 0: The size in bytes (from the offset specified in EBX) of the save area for an extended state feature associated with a valid sub-leaf index, n. EBX Bits 31 - 0: The offset in bytes of this extended state component’s save area from the beginning of the XSAVE/XRSTOR area. This field reports 0 if the sub-leaf index, n, does not map to a valid bit in the XCR0 register*. ECX Bit 00 is set if the bit n (corresponding to the sub-leaf index) is supported in the IA32_XSS MSR; it is clear if bit n is instead supported in XCR0. Bit 01 is set if, when the compacted format of an XSAVE area is used, this extended state component located on the next 64-byte boundary following the preceding state component (otherwise, it is located immediately following the preceding state component). Bits 31 - 02 are reserved. This field reports 0 if the sub-leaf index, n, is invalid*. EDX This field reports 0 if the sub-leaf index, n, is invalid*; otherwise it is reserved. |
| Intel Resource Director Technology (Intel RDT) Monitoring Enumeration Sub-leaf (EAX = 0FH, ECX = 0) | |
| 0FH | NOTES: Leaf 0FH output depends on the initial value in ECX. Sub-leaf index 0 reports valid resource type starting at bit position 1 of EDX. EAX Reserved. EBX Bits 31 - 00: Maximum range (zero-based) of RMID within this physical processor of all types. ECX Reserved. EDX Bit 00: Reserved. Bit 01: Supports L3 Cache Intel RDT Monitoring if 1. Bits 31 - 02: Reserved. |
| L3 Cache Intel RDT Monitoring Capability Enumeration Sub-leaf (EAX = 0FH, ECX = 1) | |
| 0FH | NOTES: Leaf 0FH output depends on the initial value in ECX. EAX Reserved. EBX Bits 31 - 00: Conversion factor from reported IA32_QM_CTR value to occupancy metric (bytes) and Memory Bandwidth Monitoring (MBM) metrics. ECX Maximum range (zero-based) of RMID of this resource type. EDX Bit 00: Supports L3 occupancy monitoring if 1. Bit 01: Supports L3 Total Bandwidth monitoring if 1. Bit 02: Supports L3 Local Bandwidth monitoring if 1. Bits 31 - 03: Reserved. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| Intel Resource Director Technology (Intel RDT) Allocation Enumeration Sub-leaf (EAX = 10H, ECX = 0) | |
| 10H | NOTES: Leaf 10H output depends on the initial value in ECX. Sub-leaf index 0 reports valid resource identification (ResID) starting at bit position 1 of EBX. EAX Reserved. EBX Bit 00: Reserved. Bit 01: Supports L3 Cache Allocation Technology if 1. Bit 02: Supports L2 Cache Allocation Technology if 1. Bit 03: Supports Memory Bandwidth Allocation if 1. Bits 31 - 04: Reserved. ECX Reserved. EDX Reserved. |
| L3 Cache Allocation Technology Enumeration Sub-leaf (EAX = 10H, ECX = ResID =1) | |
| 10H | NOTES: Leaf 10H output depends on the initial value in ECX. EAX Bits 04 - 00: Length of the capacity bit mask for the corresponding ResID using minus-one notation. Bits 31 - 05: Reserved. EBX Bits 31 - 00: Bit-granular map of isolation/contention of allocation units. ECX Bits 01- 00: Reserved. Bit 02: Code and Data Prioritization Technology supported if 1. Bits 31 - 03: Reserved. EDX Bits 15 - 00: Highest COS number supported for this ResID. Bits 31 - 16: Reserved. |
| L2 Cache Allocation Technology Enumeration Sub-leaf (EAX = 10H, ECX = ResID =2) | |
| 10H | NOTES: Leaf 10H output depends on the initial value in ECX. EAX Bits 04 - 00: Length of the capacity bit mask for the corresponding ResID using minus-one notation. Bits 31 - 05: Reserved. EBX Bits 31 - 00: Bit-granular map of isolation/contention of allocation units. ECX Bits 31 - 00: Reserved. EDX Bits 15 - 00: Highest COS number supported for this ResID. Bits 31 - 16: Reserved. |
| Memory Bandwidth Allocation Enumeration Sub-leaf (EAX = 10H, ECX = ResID =3) | |
| 10H | NOTES: Leaf 10H output depends on the initial value in ECX. EAX Bits 11 - 00: Reports the maximum MBA throttling value supported for the corresponding ResID using minus-one notation. Bits 31 - 12: Reserved. EBX Bits 31 - 00: Reserved. ECX Bits 01 - 00: Reserved. Bit 02: Reports whether the response of the delay values is linear. Bits 31 - 03: Reserved. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| EDX Bits 15 - 00: Highest COS number supported for this ResID. Bits 31 - 16: Reserved. | |
| Intel SGX Capability Enumeration Leaf, sub-leaf 0 (EAX = 12H, ECX = 0) | |
| 12H | NOTES: Leaf 12H sub-leaf 0 (ECX = 0) is supported if CPUID.(EAX=07H, ECX=0H):EBX[SGX] = 1. EAX Bit 00: SGX1. If 1, Indicates Intel SGX supports the collection of SGX1 leaf functions. Bit 01: SGX2. If 1, Indicates Intel SGX supports the collection of SGX2 leaf functions. Bits 04 - 02: Reserved. Bit 05: If 1, indicates Intel SGX supports ENCLV instruction leaves EINCVIRTCHILD, EDECVIRTCHILD, and ESETCONTEXT. Bit 06: If 1, indicates Intel SGX supports ENCLS instruction leaves ETRACKC, ERDINFO, ELDBC, and ELDUC. Bits 31 - 07: Reserved. EBX Bits 31 - 00: MISCSELECT. Bit vector of supported extended SGX features. ECX Bits 31 - 00: Reserved. EDX Bits 07 - 00: MaxEnclaveSize_Not64. The maximum supported enclave size in non-64-bit mode is 2^(EDX[7:0]). Bits 15 - 08: MaxEnclaveSize_64. The maximum supported enclave size in 64-bit mode is 2^(EDX[15:8]). Bits 31 - 16: Reserved. |
| Intel SGX Attributes Enumeration Leaf, sub-leaf 1 (EAX = 12H, ECX = 1) | |
| 12H | NOTES: Leaf 12H sub-leaf 1 (ECX = 1) is supported if CPUID.(EAX=07H, ECX=0H):EBX[SGX] = 1. EAX Bit 31 - 00: Reports the valid bits of SECS.ATTRIBUTES[31:0] that software can set with ECREATE. EBX Bit 31 - 00: Reports the valid bits of SECS.ATTRIBUTES[63:32] that software can set with ECREATE. ECX Bit 31 - 00: Reports the valid bits of SECS.ATTRIBUTES[95:64] that software can set with ECREATE. EDX Bit 31 - 00: Reports the valid bits of SECS.ATTRIBUTES[127:96] that software can set with ECREATE. |
| Intel SGX EPC Enumeration Leaf, sub-leaves (EAX = 12H, ECX = 2 or higher) | |
| 12H | NOTES: Leaf 12H sub-leaf 2 or higher (ECX >= 2) is supported if CPUID.(EAX=07H, ECX=0H):EBX[SGX] = 1. For sub-leaves (ECX = 2 or higher), definition of EDX,ECX,EBX,EAX[31:4] depends on the sub-leaf type listed below. EAX Bit 03 - 00: Sub-leaf Type 0000b: Indicates this sub-leaf is invalid. 0001b: This sub-leaf enumerates an EPC section. EBX:EAX and EDX:ECX provide information on the Enclave Page Cache (EPC) section. All other type encodings are reserved. Type 0000b. This sub-leaf is invalid. EDX:ECX:EBX:EAX return 0. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| Type 0001b. This sub-leaf enumerates an EPC sections with EDX:ECX, EBX:EAX defined as follows. EAX[11:04]: Reserved (enumerate 0). EAX[31:12]: Bits 31:12 of the physical address of the base of the EPC section. EBX[19:00]: Bits 51:32 of the physical address of the base of the EPC section. EBX[31:20]: Reserved. ECX[03:00]: EPC section property encoding defined as follows: If EAX[3:0] 0000b, then all bits of the EDX:ECX pair are enumerated as 0. If EAX[3:0] 0001b, then this section has confidentiality and integrity protection. All other encodings are reserved. ECX[11:04]: Reserved (enumerate 0). ECX[31:12]: Bits 31:12 of the size of the corresponding EPC section within the Processor Reserved Memory. EDX[19:00]: Bits 51:32 of the size of the corresponding EPC section within the Processor Reserved Memory. EDX[31:20]: Reserved. | |
| Intel Processor Trace Enumeration Main Leaf (EAX = 14H, ECX = 0) | |
| 14H | NOTES: Leaf 14H main leaf (ECX = 0). EAX Bits 31 - 00: Reports the maximum sub-leaf supported in leaf 14H. EBX Bit 00: If 1, indicates that IA32_RTIT_CTL.CR3Filter can be set to 1, and that IA32_RTIT_CR3_MATCH MSR can be accessed. Bit 01: If 1, indicates support of Configurable PSB and Cycle-Accurate Mode. Bit 02: If 1, indicates support of IP Filtering, TraceStop filtering, and preservation of Intel PT MSRs across warm reset. Bit 03: If 1, indicates support of MTC timing packet and suppression of COFI-based packets. Bit 04: If 1, indicates support of PTWRITE. Writes can set IA32_RTIT_CTL[12] (PTWEn) and IA32_RTIT_CTL[5] (FUPonPTW), and PTWRITE can generate packets. Bit 05: If 1, indicates support of Power Event Trace. Writes can set IA32_RTIT_CTL[4] (PwrEvtEn), enabling Power Event Trace packet generation. Bit 31 - 06: Reserved. ECX Bit 00: If 1, Tracing can be enabled with IA32_RTIT_CTL.ToPA = 1, hence utilizing the ToPA output scheme; IA32_RTIT_OUTPUT_BASE and IA32_RTIT_OUTPUT_MASK_PTRS MSRs can be accessed. Bit 01: If 1, ToPA tables can hold any number of output entries, up to the maximum allowed by the MaskOrTableOffset field of IA32_RTIT_OUTPUT_MASK_PTRS. Bit 02: If 1, indicates support of Single-Range Output scheme. Bit 03: If 1, indicates support of output to Trace Transport subsystem. Bit 30 - 04: Reserved. Bit 31: If 1, generated packets which contain IP payloads have LIP values, which include the CS base component. EDX Bits 31 - 00: Reserved. |
| Intel Processor Trace Enumeration Sub-leaf (EAX = 14H, ECX = 1) | |
| 14H | EAX Bits 02 - 00: Number of configurable Address Ranges for filtering. Bits 15 - 03: Reserved. Bits 31 - 16: Bitmap of supported MTC period encodings. EBX Bits 15 - 00: Bitmap of supported Cycle Threshold value encodings. Bit 31 - 16: Bitmap of supported Configurable PSB frequency encodings. ECX Bits 31 - 00: Reserved. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| EDX Bits 31 - 00: Reserved. | |
| Time Stamp Counter and Nominal Core Crystal Clock Information Leaf | |
| 15H | NOTES: If EBX[31:0] is 0, the TSC/”core crystal clock” ratio is not enumerated. EBX[31:0]/EAX[31:0] indicates the ratio of the TSC frequency and the core crystal clock frequency. If ECX is 0, the nominal core crystal clock frequency is not enumerated. “TSC frequency” = “core crystal clock frequency” * EBX/EAX. The core crystal clock may differ from the reference clock, bus clock, or core clock frequencies. EAX Bits 31 - 00: An unsigned integer which is the denominator of the TSC/”core crystal clock” ratio. EBX Bits 31 - 00: An unsigned integer which is the numerator of the TSC/”core crystal clock” ratio. ECX Bits 31 - 00: An unsigned integer which is the nominal frequency of the core crystal clock in Hz. EDX Bits 31 - 00: Reserved = 0. |
| Processor Frequency Information Leaf | |
| 16H | EAX Bits 15 - 00: Processor Base Frequency (in MHz). Bits 31 - 16: Reserved =0. EBX Bits 15 - 00: Maximum Frequency (in MHz). Bits 31 - 16: Reserved = 0. ECX Bits 15 - 00: Bus (Reference) Frequency (in MHz). Bits 31 - 16: Reserved = 0. EDX Reserved. NOTES: * Data is returned from this interface in accordance with the processor's specification and does not reflect actual values. Suitable use of this data includes the display of processor information in like manner to the processor brand string and for determining the appropriate range to use when displaying processor information e.g. frequency history graphs. The returned information should not be used for any other purpose as the returned information does not accurately correlate to information / counters returned by other processor interfaces. While a processor may support the Processor Frequency Information leaf, fields that return a value of zero are not supported. |
| System-On-Chip Vendor Attribute Enumeration Main Leaf (EAX = 17H, ECX = 0) | |
| 17H | NOTES: Leaf 17H main leaf (ECX = 0). Leaf 17H output depends on the initial value in ECX. Leaf 17H sub-leaves 1 through 3 reports SOC Vendor Brand String. Leaf 17H is valid if MaxSOCID_Index >= 3. Leaf 17H sub-leaves 4 and above are reserved. EAX Bits 31 - 00: MaxSOCID_Index. Reports the maximum input value of supported sub-leaf in leaf 17H. EBX Bits 15 - 00: SOC Vendor ID. Bit 16: IsVendorScheme. If 1, the SOC Vendor ID field is assigned via an industry standard enumeration scheme. Otherwise, the SOC Vendor ID field is assigned by Intel. Bits 31 - 17: Reserved = 0. ECX Bits 31 - 00: Project ID. A unique number an SOC vendor assigns to its SOC projects. EDX Bits 31 - 00: Stepping ID. A unique number within an SOC project that an SOC vendor assigns. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| System-On-Chip Vendor Attribute Enumeration Sub-leaf (EAX = 17H, ECX = 1..3) | |
| 17H | EAX Bit 31 - 00: SOC Vendor Brand String. UTF-8 encoded string. EBX Bit 31 - 00: SOC Vendor Brand String. UTF-8 encoded string. ECX Bit 31 - 00: SOC Vendor Brand String. UTF-8 encoded string. EDX Bit 31 - 00: SOC Vendor Brand String. UTF-8 encoded string. NOTES: Leaf 17H output depends on the initial value in ECX. SOC Vendor Brand String is a UTF-8 encoded string padded with trailing bytes of 00H. The complete SOC Vendor Brand String is constructed by concatenating in ascending order of EAX:EBX:ECX:EDX and from the sub-leaf 1 fragment towards sub-leaf 3. |
| System-On-Chip Vendor Attribute Enumeration Sub-leaves (EAX = 17H, ECX > MaxSOCID_Index) | |
| 17H | NOTES: Leaf 17H output depends on the initial value in ECX. EAX Bits 31 - 00: Reserved = 0. EBX Bits 31 - 00: Reserved = 0. ECX Bits 31 - 00: Reserved = 0. EDX Bits 31 - 00: Reserved = 0. |
| Deterministic Address Translation Parameters Main Leaf (EAX = 18H, ECX = 0) | |
| 18H | NOTES: Each sub-leaf enumerates a different address translation structure. If ECX contains an invalid sub-leaf index, EAX/EBX/ECX/EDX return 0. Sub-leaf index n is invalid if n exceeds the value that sub-leaf 0 returns in EAX. A sub-leaf index is also invalid if EDX[4:0] returns 0. Valid sub-leaves do not need to be contiguous or in any particular order. A valid sub-leaf may be in a higher input ECX value than an invalid sub-leaf or than a valid sub-leaf of a higher or lower-level structure. * Some unified TLBs will allow a single TLB entry to satisfy data read/write and instruction fetches. Others will require separate entries (e.g., one loaded on data read/write and another loaded on an instruction fetch) . Please see the Intel® 64 and IA-32 Architectures Optimization Reference Manual for details of a particular product. ** Add one to the return value to get the result. EAX Bits 31 - 00: Reports the maximum input value of supported sub-leaf in leaf 18H. EBX Bit 00: 4K page size entries supported by this structure. Bit 01: 2MB page size entries supported by this structure. Bit 02: 4MB page size entries supported by this structure. Bit 03: 1 GB page size entries supported by this structure. Bits 07 - 04: Reserved. Bits 10 - 08: Partitioning (0: Soft partitioning between the logical processors sharing this structure). Bits 15 - 11: Reserved. Bits 31 - 16: W = Ways of associativity. ECX Bits 31 - 00: S = Number of Sets. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| EDX Bits 04 - 00: Translation cache type field. 00000b: Null (indicates this sub-leaf is not valid). 00001b: Data TLB. 00010b: Instruction TLB. 00011b: Unified TLB*. All other encodings are reserved. Bits 07 - 05: Translation cache level (starts at 1). Bit 08: Fully associative structure. Bits 13 - 09: Reserved. Bits 25- 14: Maximum number of addressable IDs for logical processors sharing this translation cache** Bits 31 - 26: Reserved. | |
| Deterministic Address Translation Parameters Sub-leaf (EAX = 18H, ECX ≥ 1) | |
| 18H | NOTES: Each sub-leaf enumerates a different address translation structure. If ECX contains an invalid sub-leaf index, EAX/EBX/ECX/EDX return 0. Sub-leaf index n is invalid if n exceeds the value that sub-leaf 0 returns in EAX. A sub-leaf index is also invalid if EDX[4:0] returns 0. Valid sub-leaves do not need to be contiguous or in any particular order. A valid sub-leaf may be in a higher input ECX value than an invalid sub-leaf or than a valid sub-leaf of a higher or lower-level structure. * Some unified TLBs will allow a single TLB entry to satisfy data read/write and instruction fetches. Others will require separate entries (e.g., one loaded on data read/write and another loaded on an instruction fetch) . Please see the Intel® 64 and IA-32 Architectures Optimization Reference Manual for details of a particular product. ** Add one to the return value to get the result. EAX Bits 31 - 00: Reserved. EBX Bit 00: 4K page size entries supported by this structure. Bit 01: 2MB page size entries supported by this structure. Bit 02: 4MB page size entries supported by this structure. Bit 03: 1 GB page size entries supported by this structure. Bits 07 - 04: Reserved. Bits 10 - 08: Partitioning (0: Soft partitioning between the logical processors sharing this structure). Bits 15 - 11: Reserved. Bits 31 - 16: W = Ways of associativity. ECX Bits 31 - 00: S = Number of Sets. EDX Bits 04 - 00: Translation cache type field. 0000b: Null (indicates this sub-leaf is not valid). 0001b: Data TLB. 0010b: Instruction TLB. 0011b: Unified TLB*. All other encodings are reserved. Bits 07 - 05: Translation cache level (starts at 1). Bit 08: Fully associative structure. Bits 13 - 09: Reserved. Bits 25- 14: Maximum number of addressable IDs for logical processors sharing this translation cache** Bits 31 - 26: Reserved. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| V2 Extended Topology Enumeration Leaf | |
| 1FH | NOTES: CPUID leaf 1FH is a preferred superset to leaf 0BH. Intel recommends first checking for the existence of Leaf 1FH and using this if available. Most of Leaf 1FH output depends on the initial value in ECX. The EDX output of leaf 1FH is always valid and does not vary with input value in ECX. Output value in ECX[7:0] always equals input value in ECX[7:0]. Sub-leaf index 0 enumerates SMT level. Each subsequent higher sub-leaf index enumerates a higher-level topological entity in hierarchical order. For sub-leaves that return an invalid level-type of 0 in ECX[15:8]; EAX and EBX will return 0. If an input value n in ECX returns the invalid level-type of 0 in ECX[15:8], other input values with ECX > n also return 0 in ECX[15:8]. EAX Bits 04 - 00: Number of bits to shift right on x2APIC ID to get a unique topology ID of the next level type*. All logical processors with the same next level ID share current level. Bits 31 - 05: Reserved. EBX Bits 15 - 00: Number of logical processors at this level type. The number reflects configuration as shipped by Intel**. Bits 31- 16: Reserved. ECX Bits 07 - 00: Level number. Same value in ECX input. Bits 15 - 08: Level type***. Bits 31 - 16: Reserved. EDX Bits 31- 00: x2APIC ID the current logical processor. NOTES: * Software should use this field (EAX[4:0]) to enumerate processor topology of the system. ** Software must not use EBX[15:0] to enumerate processor topology of the system. This value in this field (EBX[15:0]) is only intended for display/diagnostic purposes. The actual number of logical processors available to BIOS/OS/Applications may be different from the value of EBX[15:0], depending on software and platform hardware configurations. *** The value of the “level type” field is not related to level numbers in any way, higher “level type” values do not mean higher levels. Level type field has the following encoding: 0: Invalid. 1: SMT. 2: Core. 3: Module. 4: Tile. 5: Die. 6-255: Reserved. |
| Unimplemented CPUID Leaf Functions | |
| 40000000H -4FFFFFFFH | Invalid. No existing or future CPU will return processor identification or feature information if the initial EAX value is in the range 40000000H to 4FFFFFFFH. |
| Extended Function CPUID Information | |
| 80000000H | EAX Maximum Input Value for Extended Function CPUID Information. EBX Reserved. ECX Reserved. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| EDX Reserved. | |
| 80000001H | EAX Extended Processor Signature and Feature Bits. EBX Reserved. ECX Bit 00: LAHF/SAHF available in 64-bit mode.* Bits 04 - 01: Reserved. Bit 05: LZCNT. Bits 07 - 06: Reserved. Bit 08: PREFETCHW. Bits 31 - 09: Reserved. EDX Bits 10 - 00: Reserved. Bit 11: SYSCALL/SYSRET.** Bits 19 - 12: Reserved = 0. Bit 20: Execute Disable Bit available. Bits 25 - 21: Reserved = 0. Bit 26: 1-GByte pages are available if 1. Bit 27: RDTSCP and IA32_TSC_AUX are available if 1. Bit 28: Reserved = 0. Bit 29: Intel® 64 Architecture available if 1. Bits 31 - 30: Reserved = 0. NOTES: * LAHFandSAHFarealwaysavailableinothermodes,regardlessoftheenumerationofthisfeatureflag. ** Intel processors support SYSCALL and SYSRET only in 64-bit mode. This feature flag is always enumerated as 0 outside 64-bit mode. |
| 80000002H | EAX Processor Brand String. EBX Processor Brand String Continued. ECX Processor Brand String Continued. EDX Processor Brand String Continued. |
| 80000003H | EAX Processor Brand String Continued. EBX Processor Brand String Continued. ECX Processor Brand String Continued. EDX Processor Brand String Continued. |
| 80000004H | EAX Processor Brand String Continued. EBX Processor Brand String Continued. ECX Processor Brand String Continued. EDX Processor Brand String Continued. |
| 80000005H | EAX Reserved = 0. EBX Reserved = 0. ECX Reserved = 0. EDX Reserved = 0. |
| 80000006H | EAX Reserved = 0. EBX Reserved = 0. ECX Bits 07 - 00: Cache Line size in bytes. Bits 11 - 08: Reserved. Bits 15 - 12: L2 Associativity field *. Bits 31 - 16: Cache size in 1K units. EDX Reserved = 0. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
| Initial EAX Value | Information Provided about the Processor |
|---|---|
| NOTES: * L2 associativity field encodings: 00H - Disabled 08H - 16 ways 01H - 1 way (direct mapped) 09H - Reserved 02H - 2 ways 0AH - 32 ways 03H - Reserved 0BH - 48 ways 04H - 4 ways 0CH - 64 ways 05H - Reserved 0DH - 96 ways 06H - 8 ways 0EH - 128 ways 07H - See CPUID leaf 04H, sub-leaf 2** 0FH - Fully associative ** CPUID leaf 04H provides details of deterministic cache parameters, including the L2 cache in sub-leaf 2 | |
| 80000007H | EAX Reserved = 0. EBX Reserved = 0. ECX Reserved = 0. EDX Bits 07 - 00: Reserved = 0. Bit 08: Invariant TSC available if 1. Bits 31 - 09: Reserved = 0. |
| 80000008H | EAX Linear/Physical Address size. Bits 07 - 00: #Physical Address Bits*. Bits 15 - 08: #Linear Address Bits. Bits 31 - 16: Reserved = 0. EBX Reserved = 0. ECX Reserved = 0. EDX Reserved = 0. NOTES: * IfCPUID.80000008H:EAX[7:0]issupported,themaximumphysicaladdressnumbersupportedshould come from this field. |
Table 3-8. Information Returned by CPUID Instruction (Contd.)
INPUT EAX = 0: Returns CPUID’s Highest Value for Basic Processor Information and the Vendor Identification String ¶
When CPUID executes with EAX set to 0, the processor returns the highest value the CPUID recognizes for returning basic processor information. The value is returned in the EAX register and is processor specific.
A vendor identification string is also returned in EBX, EDX, and ECX. For Intel processors, the string is “GenuineIntel” and is expressed:
EBX ← 756e6547h (* “Genu”, with G in the low eight bits of BL *) EDX ← 49656e69h (* “ineI”, with i in the low eight bits of DL *) ECX ← 6c65746eh (* “ntel”, with n in the low eight bits of CL *)
INPUT EAX = 80000000H: Returns CPUID’s Highest Value for Extended Processor Information ¶
When CPUID executes with EAX set to 80000000H, the processor returns the highest value the processor recognizes for returning extended processor information. The value is returned in the EAX register and is processor specific.
IA32_BIOS_SIGN_ID Returns Microcode Update Signature ¶
For processors that support the microcode update facility, the IA32_BIOS_SIGN_ID MSR is loaded with the update signature whenever CPUID executes. The signature is returned in the upper DWORD. For details, see Chapter 9 in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 3A.
INPUT EAX = 01H: Returns Model, Family, Stepping Information ¶
When CPUID executes with EAX set to 01H, version information is returned in EAX (see Figure 3-6). For example: model, family, and processor type for the Intel Xeon processor 5100 series is as follows:
- Model — 1111B
- Family — 0101B
- Processor Type — 00B
See Table 3-9 for available processor type values. Stepping IDs are provided as needed.
Figure 3-6. Version Information Returned by CPUID in EAX
| Type | Encoding |
|---|---|
| Original OEM Processor | 00B |
| Intel OverDrive® Processor | 01B |
| Dual processor (not applicable to Intel486 processors) | 10B |
| Intel reserved | 11B |
Table 3-9. Processor Type Field
See Chapter 19 in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 1, for information on identifying earlier IA-32 processors.
The Extended Family ID needs to be examined only when the Family ID is 0FH. Integrate the fields into a display using the following rule:
IF Family_ID ≠ 0FH THEN DisplayFamily = Family_ID;
ELSE DisplayFamily = Extended_Family_ID + Family_ID;
(* Right justify and zero-extend 4-bit field. *)
FI;
(* Show DisplayFamily as HEX field. *)
The Extended Model ID needs to be examined only when the Family ID is 06H or 0FH. Integrate the field into a display using the following rule:
IF (Family_ID = 06H or Family_ID = 0FH)
THEN DisplayModel = (Extended_Model_ID « 4) + Model_ID;
(* Right justify and zero-extend 4-bit field; display Model_ID as HEX field.*)
ELSE DisplayModel = Model_ID;
FI;
(* Show DisplayModel as HEX field. *)
INPUT EAX = 01H: Returns Additional Information in EBX ¶
When CPUID executes with EAX set to 01H, 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)
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