matterbridge/vendor/github.com/klauspost/cpuid/v2/README.md

cpuid

Package cpuid provides information about the CPU running the current program.

CPU features are detected on startup, and kept for fast access through the life of the application. Currently x86 / x64 (AMD64/i386) and ARM (ARM64) is supported, and no external C (cgo) code is used, which should make the library very easy to use.

You can access the CPU information by accessing the shared CPU variable of the cpuid library.

Package home: https://github.com/klauspost/cpuid

installing

go get -u github.com/klauspost/cpuid/v2 using modules. Drop v2 for others.

Homebrew

For macOS/Linux users, you can install via brew

$ brew install cpuid

example

package main

import (
	"fmt"
	"strings"

	. "github.com/klauspost/cpuid/v2"
)

func main() {
	// Print basic CPU information:
	fmt.Println("Name:", CPU.BrandName)
	fmt.Println("PhysicalCores:", CPU.PhysicalCores)
	fmt.Println("ThreadsPerCore:", CPU.ThreadsPerCore)
	fmt.Println("LogicalCores:", CPU.LogicalCores)
	fmt.Println("Family", CPU.Family, "Model:", CPU.Model, "Vendor ID:", CPU.VendorID)
	fmt.Println("Features:", strings.Join(CPU.FeatureSet(), ","))
	fmt.Println("Cacheline bytes:", CPU.CacheLine)
	fmt.Println("L1 Data Cache:", CPU.Cache.L1D, "bytes")
	fmt.Println("L1 Instruction Cache:", CPU.Cache.L1I, "bytes")
	fmt.Println("L2 Cache:", CPU.Cache.L2, "bytes")
	fmt.Println("L3 Cache:", CPU.Cache.L3, "bytes")
	fmt.Println("Frequency", CPU.Hz, "hz")

	// Test if we have these specific features:
	if CPU.Supports(SSE, SSE2) {
		fmt.Println("We have Streaming SIMD 2 Extensions")
	}
}

Sample output:

>go run main.go
Name: AMD Ryzen 9 3950X 16-Core Processor
PhysicalCores: 16
ThreadsPerCore: 2
LogicalCores: 32
Family 23 Model: 113 Vendor ID: AMD
Features: ADX,AESNI,AVX,AVX2,BMI1,BMI2,CLMUL,CMOV,CX16,F16C,FMA3,HTT,HYPERVISOR,LZCNT,MMX,MMXEXT,NX,POPCNT,RDRAND,RDSEED,RDTSCP,SHA,SSE,SSE2,SSE3,SSE4,SSE42,SSE4A,SSSE3
Cacheline bytes: 64
L1 Data Cache: 32768 bytes
L1 Instruction Cache: 32768 bytes
L2 Cache: 524288 bytes
L3 Cache: 16777216 bytes
Frequency 0 hz
We have Streaming SIMD 2 Extensions

usage

The cpuid.CPU provides access to CPU features. Use cpuid.CPU.Supports() to check for CPU features. A faster cpuid.CPU.Has() is provided which will usually be inlined by the gc compiler.

To test a larger number of features, they can be combined using f := CombineFeatures(CMOV, CMPXCHG8, X87, FXSR, MMX, SYSCALL, SSE, SSE2), etc. This can be using with cpuid.CPU.HasAll(f) to quickly test if all features are supported.

Note that for some cpu/os combinations some features will not be detected. amd64 has rather good support and should work reliably on all platforms.

Note that hypervisors may not pass through all CPU features through to the guest OS, so even if your host supports a feature it may not be visible on guests.

arm64 feature detection

Not all operating systems provide ARM features directly and there is no safe way to do so for the rest.

Currently arm64/linux and arm64/freebsd should be quite reliable. arm64/darwin adds features expected from the M1 processor, but a lot remains undetected.

A DetectARM() can be used if you are able to control your deployment, it will detect CPU features, but may crash if the OS doesn't intercept the calls. A -cpu.arm flag for detecting unsafe ARM features can be added. See below.

Note that currently only features are detected on ARM, no additional information is currently available.

flags

It is possible to add flags that affects cpu detection.

For this the Flags() command is provided.

This must be called before flag.Parse() AND after the flags have been parsed Detect() must be called.

This means that any detection used in init() functions will not contain these flags.

Example:

package main

import (
	"flag"
	"fmt"
	"strings"

	"github.com/klauspost/cpuid/v2"
)

func main() {
	cpuid.Flags()
	flag.Parse()
	cpuid.Detect()

	// Test if we have these specific features:
	if cpuid.CPU.Supports(cpuid.SSE, cpuid.SSE2) {
		fmt.Println("We have Streaming SIMD 2 Extensions")
	}
}

commandline

Download as binary from: https://github.com/klauspost/cpuid/releases

Install from source:

go install github.com/klauspost/cpuid/v2/cmd/cpuid@latest

Example

λ cpuid
Name: AMD Ryzen 9 3950X 16-Core Processor
Vendor String: AuthenticAMD
Vendor ID: AMD
PhysicalCores: 16
Threads Per Core: 2
Logical Cores: 32
CPU Family 23 Model: 113
Features: ADX,AESNI,AVX,AVX2,BMI1,BMI2,CLMUL,CLZERO,CMOV,CMPXCHG8,CPBOOST,CX16,F16C,FMA3,FXSR,FXSROPT,HTT,HYPERVISOR,LAHF,LZCNT,MCAOVERFLOW,MMX,MMXEXT,MOVBE,NX,OSXSAVE,POPCNT,RDRAND,RDSEED,RDTSCP,SCE,SHA,SSE,SSE2,SSE3,SSE4,SSE42,SSE4A,SSSE3,SUCCOR,X87,XSAVE
Microarchitecture level: 3
Cacheline bytes: 64
L1 Instruction Cache: 32768 bytes
L1 Data Cache: 32768 bytes
L2 Cache: 524288 bytes
L3 Cache: 16777216 bytes

JSON Output:

λ cpuid --json
{
  "BrandName": "AMD Ryzen 9 3950X 16-Core Processor",
  "VendorID": 2,
  "VendorString": "AuthenticAMD",
  "PhysicalCores": 16,
  "ThreadsPerCore": 2,
  "LogicalCores": 32,
  "Family": 23,
  "Model": 113,
  "CacheLine": 64,
  "Hz": 0,
  "BoostFreq": 0,
  "Cache": {
    "L1I": 32768,
    "L1D": 32768,
    "L2": 524288,
    "L3": 16777216
  },
  "SGX": {
    "Available": false,
    "LaunchControl": false,
    "SGX1Supported": false,
    "SGX2Supported": false,
    "MaxEnclaveSizeNot64": 0,
    "MaxEnclaveSize64": 0,
    "EPCSections": null
  },
  "Features": [
    "ADX",
    "AESNI",
    "AVX",
    "AVX2",
    "BMI1",
    "BMI2",
    "CLMUL",
    "CLZERO",
    "CMOV",
    "CMPXCHG8",
    "CPBOOST",
    "CX16",
    "F16C",
    "FMA3",
    "FXSR",
    "FXSROPT",
    "HTT",
    "HYPERVISOR",
    "LAHF",
    "LZCNT",
    "MCAOVERFLOW",
    "MMX",
    "MMXEXT",
    "MOVBE",
    "NX",
    "OSXSAVE",
    "POPCNT",
    "RDRAND",
    "RDSEED",
    "RDTSCP",
    "SCE",
    "SHA",
    "SSE",
    "SSE2",
    "SSE3",
    "SSE4",
    "SSE42",
    "SSE4A",
    "SSSE3",
    "SUCCOR",
    "X87",
    "XSAVE"
  ],
  "X64Level": 3
}

Check CPU microarch level

λ cpuid --check-level=3
2022/03/18 17:04:40 AMD Ryzen 9 3950X 16-Core Processor
2022/03/18 17:04:40 Microarchitecture level 3 is supported. Max level is 3.
Exit Code 0

λ cpuid --check-level=4
2022/03/18 17:06:18 AMD Ryzen 9 3950X 16-Core Processor
2022/03/18 17:06:18 Microarchitecture level 4 not supported. Max level is 3.
Exit Code 1

Available flags

x86 & amd64

Feature Flag	Description
ADX	Intel ADX (Multi-Precision Add-Carry Instruction Extensions)
AESNI	Advanced Encryption Standard New Instructions
AMD3DNOW	AMD 3DNOW
AMD3DNOWEXT	AMD 3DNowExt
AMXBF16	Tile computational operations on BFLOAT16 numbers
AMXINT8	Tile computational operations on 8-bit integers
AMXFP16	Tile computational operations on FP16 numbers
AMXTILE	Tile architecture
AVX	AVX functions
AVX2	AVX2 functions
AVX512BF16	AVX-512 BFLOAT16 Instructions
AVX512BITALG	AVX-512 Bit Algorithms
AVX512BW	AVX-512 Byte and Word Instructions
AVX512CD	AVX-512 Conflict Detection Instructions
AVX512DQ	AVX-512 Doubleword and Quadword Instructions
AVX512ER	AVX-512 Exponential and Reciprocal Instructions
AVX512F	AVX-512 Foundation
AVX512FP16	AVX-512 FP16 Instructions
AVX512IFMA	AVX-512 Integer Fused Multiply-Add Instructions
AVX512PF	AVX-512 Prefetch Instructions
AVX512VBMI	AVX-512 Vector Bit Manipulation Instructions
AVX512VBMI2	AVX-512 Vector Bit Manipulation Instructions, Version 2
AVX512VL	AVX-512 Vector Length Extensions
AVX512VNNI	AVX-512 Vector Neural Network Instructions
AVX512VP2INTERSECT	AVX-512 Intersect for D/Q
AVX512VPOPCNTDQ	AVX-512 Vector Population Count Doubleword and Quadword
AVXIFMA	AVX-IFMA instructions
AVXNECONVERT	AVX-NE-CONVERT instructions
AVXSLOW	Indicates the CPU performs 2 128 bit operations instead of one
AVXVNNI	AVX (VEX encoded) VNNI neural network instructions
AVXVNNIINT8	AVX-VNNI-INT8 instructions
BMI1	Bit Manipulation Instruction Set 1
BMI2	Bit Manipulation Instruction Set 2
CETIBT	Intel CET Indirect Branch Tracking
CETSS	Intel CET Shadow Stack
CLDEMOTE	Cache Line Demote
CLMUL	Carry-less Multiplication
CLZERO	CLZERO instruction supported
CMOV	i686 CMOV
CMPCCXADD	CMPCCXADD instructions
CMPSB_SCADBS_SHORT	Fast short CMPSB and SCASB
CMPXCHG8	CMPXCHG8 instruction
CPBOOST	Core Performance Boost
CPPC	AMD: Collaborative Processor Performance Control
CX16	CMPXCHG16B Instruction
EFER_LMSLE_UNS	AMD: =Core::X86::Msr::EFER[LMSLE] is not supported, and MBZ
ENQCMD	Enqueue Command
ERMS	Enhanced REP MOVSB/STOSB
F16C	Half-precision floating-point conversion
FLUSH_L1D	Flush L1D cache
FMA3	Intel FMA 3. Does not imply AVX.
FMA4	Bulldozer FMA4 functions
FP128	AMD: When set, the internal FP/SIMD execution datapath is 128-bits wide
FP256	AMD: When set, the internal FP/SIMD execution datapath is 256-bits wide
FSRM	Fast Short Rep Mov
FXSR	FXSAVE, FXRESTOR instructions, CR4 bit 9
FXSROPT	FXSAVE/FXRSTOR optimizations
GFNI	Galois Field New Instructions. May require other features (AVX, AVX512VL,AVX512F) based on usage.
HLE	Hardware Lock Elision
HRESET	If set CPU supports history reset and the IA32_HRESET_ENABLE MSR
HTT	Hyperthreading (enabled)
HWA	Hardware assert supported. Indicates support for MSRC001_10
HYBRID_CPU	This part has CPUs of more than one type.
HYPERVISOR	This bit has been reserved by Intel & AMD for use by hypervisors
IA32_ARCH_CAP	IA32_ARCH_CAPABILITIES MSR (Intel)
IA32_CORE_CAP	IA32_CORE_CAPABILITIES MSR
IBPB	Indirect Branch Restricted Speculation (IBRS) and Indirect Branch Predictor Barrier (IBPB)
IBRS	AMD: Indirect Branch Restricted Speculation
IBRS_PREFERRED	AMD: IBRS is preferred over software solution
IBRS_PROVIDES_SMP	AMD: IBRS provides Same Mode Protection
IBS	Instruction Based Sampling (AMD)
IBSBRNTRGT	Instruction Based Sampling Feature (AMD)
IBSFETCHSAM	Instruction Based Sampling Feature (AMD)
IBSFFV	Instruction Based Sampling Feature (AMD)
IBSOPCNT	Instruction Based Sampling Feature (AMD)
IBSOPCNTEXT	Instruction Based Sampling Feature (AMD)
IBSOPSAM	Instruction Based Sampling Feature (AMD)
IBSRDWROPCNT	Instruction Based Sampling Feature (AMD)
IBSRIPINVALIDCHK	Instruction Based Sampling Feature (AMD)
IBS_FETCH_CTLX	AMD: IBS fetch control extended MSR supported
IBS_OPDATA4	AMD: IBS op data 4 MSR supported
IBS_OPFUSE	AMD: Indicates support for IbsOpFuse
IBS_PREVENTHOST	Disallowing IBS use by the host supported
IBS_ZEN4	Fetch and Op IBS support IBS extensions added with Zen4
INT_WBINVD	WBINVD/WBNOINVD are interruptible.
INVLPGB	NVLPGB and TLBSYNC instruction supported
LAHF	LAHF/SAHF in long mode
LAM	If set, CPU supports Linear Address Masking
LBRVIRT	LBR virtualization
LZCNT	LZCNT instruction
MCAOVERFLOW	MCA overflow recovery support.
MCDT_NO	Processor do not exhibit MXCSR Configuration Dependent Timing behavior and do not need to mitigate it.
MCOMMIT	MCOMMIT instruction supported
MD_CLEAR	VERW clears CPU buffers
MMX	standard MMX
MMXEXT	SSE integer functions or AMD MMX ext
MOVBE	MOVBE instruction (big-endian)
MOVDIR64B	Move 64 Bytes as Direct Store
MOVDIRI	Move Doubleword as Direct Store
MOVSB_ZL	Fast Zero-Length MOVSB
MPX	Intel MPX (Memory Protection Extensions)
MOVU	MOVU SSE instructions are more efficient and should be preferred to SSE MOVL/MOVH. MOVUPS is more efficient than MOVLPS/MOVHPS. MOVUPD is more efficient than MOVLPD/MOVHPD
MSRIRC	Instruction Retired Counter MSR available
MSR_PAGEFLUSH	Page Flush MSR available
NRIPS	Indicates support for NRIP save on VMEXIT
NX	NX (No-Execute) bit
OSXSAVE	XSAVE enabled by OS
PCONFIG	PCONFIG for Intel Multi-Key Total Memory Encryption
POPCNT	POPCNT instruction
PPIN	AMD: Protected Processor Inventory Number support. Indicates that Protected Processor Inventory Number (PPIN) capability can be enabled
PREFETCHI	PREFETCHIT0/1 instructions
PSFD	AMD: Predictive Store Forward Disable
RDPRU	RDPRU instruction supported
RDRAND	RDRAND instruction is available
RDSEED	RDSEED instruction is available
RDTSCP	RDTSCP Instruction
RTM	Restricted Transactional Memory
RTM_ALWAYS_ABORT	Indicates that the loaded microcode is forcing RTM abort.
SERIALIZE	Serialize Instruction Execution
SEV	AMD Secure Encrypted Virtualization supported
SEV_64BIT	AMD SEV guest execution only allowed from a 64-bit host
SEV_ALTERNATIVE	AMD SEV Alternate Injection supported
SEV_DEBUGSWAP	Full debug state swap supported for SEV-ES guests
SEV_ES	AMD SEV Encrypted State supported
SEV_RESTRICTED	AMD SEV Restricted Injection supported
SEV_SNP	AMD SEV Secure Nested Paging supported
SGX	Software Guard Extensions
SGXLC	Software Guard Extensions Launch Control
SHA	Intel SHA Extensions
SME	AMD Secure Memory Encryption supported
SME_COHERENT	AMD Hardware cache coherency across encryption domains enforced
SPEC_CTRL_SSBD	Speculative Store Bypass Disable
SRBDS_CTRL	SRBDS mitigation MSR available
SSE	SSE functions
SSE2	P4 SSE functions
SSE3	Prescott SSE3 functions
SSE4	Penryn SSE4.1 functions
SSE42	Nehalem SSE4.2 functions
SSE4A	AMD Barcelona microarchitecture SSE4a instructions
SSSE3	Conroe SSSE3 functions
STIBP	Single Thread Indirect Branch Predictors
STIBP_ALWAYSON	AMD: Single Thread Indirect Branch Prediction Mode has Enhanced Performance and may be left Always On
STOSB_SHORT	Fast short STOSB
SUCCOR	Software uncorrectable error containment and recovery capability.
SVM	AMD Secure Virtual Machine
SVMDA	Indicates support for the SVM decode assists.
SVMFBASID	SVM, Indicates that TLB flush events, including CR3 writes and CR4.PGE toggles, flush only the current ASID's TLB entries. Also indicates support for the extended VMCBTLB_Control
SVML	AMD SVM lock. Indicates support for SVM-Lock.
SVMNP	AMD SVM nested paging
SVMPF	SVM pause intercept filter. Indicates support for the pause intercept filter
SVMPFT	SVM PAUSE filter threshold. Indicates support for the PAUSE filter cycle count threshold
SYSCALL	System-Call Extension (SCE): SYSCALL and SYSRET instructions.
SYSEE	SYSENTER and SYSEXIT instructions
TBM	AMD Trailing Bit Manipulation
TLB_FLUSH_NESTED	AMD: Flushing includes all the nested translations for guest translations
TME	Intel Total Memory Encryption. The following MSRs are supported: IA32_TME_CAPABILITY, IA32_TME_ACTIVATE, IA32_TME_EXCLUDE_MASK, and IA32_TME_EXCLUDE_BASE.
TOPEXT	TopologyExtensions: topology extensions support. Indicates support for CPUID Fn8000_001D_EAX_x[N:0]-CPUID Fn8000_001E_EDX.
TSCRATEMSR	MSR based TSC rate control. Indicates support for MSR TSC ratio MSRC000_0104
TSXLDTRK	Intel TSX Suspend Load Address Tracking
VAES	Vector AES. AVX(512) versions requires additional checks.
VMCBCLEAN	VMCB clean bits. Indicates support for VMCB clean bits.
VMPL	AMD VM Permission Levels supported
VMSA_REGPROT	AMD VMSA Register Protection supported
VMX	Virtual Machine Extensions
VPCLMULQDQ	Carry-Less Multiplication Quadword. Requires AVX for 3 register versions.
VTE	AMD Virtual Transparent Encryption supported
WAITPKG	TPAUSE, UMONITOR, UMWAIT
WBNOINVD	Write Back and Do Not Invalidate Cache
X87	FPU
XGETBV1	Supports XGETBV with ECX = 1
XOP	Bulldozer XOP functions
XSAVE	XSAVE, XRESTOR, XSETBV, XGETBV
XSAVEC	Supports XSAVEC and the compacted form of XRSTOR.
XSAVEOPT	XSAVEOPT available
XSAVES	Supports XSAVES/XRSTORS and IA32_XSS

ARM features:

Feature Flag	Description
AESARM	AES instructions
ARMCPUID	Some CPU ID registers readable at user-level
ASIMD	Advanced SIMD
ASIMDDP	SIMD Dot Product
ASIMDHP	Advanced SIMD half-precision floating point
ASIMDRDM	Rounding Double Multiply Accumulate/Subtract (SQRDMLAH/SQRDMLSH)
ATOMICS	Large System Extensions (LSE)
CRC32	CRC32/CRC32C instructions
DCPOP	Data cache clean to Point of Persistence (DC CVAP)
EVTSTRM	Generic timer
FCMA	Floatin point complex number addition and multiplication
FP	Single-precision and double-precision floating point
FPHP	Half-precision floating point
GPA	Generic Pointer Authentication
JSCVT	Javascript-style double->int convert (FJCVTZS)
LRCPC	Weaker release consistency (LDAPR, etc)
PMULL	Polynomial Multiply instructions (PMULL/PMULL2)
SHA1	SHA-1 instructions (SHA1C, etc)
SHA2	SHA-2 instructions (SHA256H, etc)
SHA3	SHA-3 instructions (EOR3, RAXI, XAR, BCAX)
SHA512	SHA512 instructions
SM3	SM3 instructions
SM4	SM4 instructions
SVE	Scalable Vector Extension

license

This code is published under an MIT license. See LICENSE file for more information.