cpuid (1) - Linux Manuals

Command to display cpuid manual in Linux: $ man 1 cpuid

NAME

cpuid - Dump CPUID information for each CPU

SYNOPSIS

cpuid [options...]

DESCRIPTION

cpuid dumps detailed information about the CPU(s) gathered from the CPUID instruction, and also determines the exact model of CPU(s) from that information.

It dumps all information available from the CPUID instruction. The exact collection of information available varies between manufacturers and processors. The following information is available consistently on all modern CPUs:

        vendor_id
        version information (1/eax)
        miscellaneous (1/ebx)
        feature information (1/ecx)

It also produces synthetic fields based on information from multiple CPUID functions. Currently, the synthetic fields are the exact model of each CPU (but see LIMITATIONS below) as (synth); the multiprocessing characteristics including the number of cores per chip (c) and the number of hyperthreads per core (t) as (multi-processing synth); and a decoding of the APIC physical ID as (APIC synth).

The determination of the model is based on the following information:

        version information (1/eax), processor type
        version information (1/eax), family
        version information (1/eax), model
        version information (1/eax), stepping id
        version information (1/eax), extended family
        version information (1/eax), extended model
        feature information (1/ecx), virtual machine extensions
        brand id (1/ebx)
        brand (0x80000004)
        cache and TLB information (2)
        deterministic cache parameters (4/eax), extra processor cores
        AMD extended brand id (0x80000001/ebx)
        AMD extended processor signature (0x80000001/eax)
        Transmeta processor revision ID (0x80860001/ebx & ecx)

The determination of the multiprocessing characteristics and decoding of APIC physical ID is based on the following information:

        feature information (1/edx), hyper-threading / multi-core supported
        miscellaneous (1/ebx), cpu count
        deterministic cache parameters (4/eax), extra processor cores on this die
        x2APIC features / processor topology (0xb)
        AMD feature flags (0x80000001/ecx)
        AMD Logical CPU cores (0x80000008/ecx), number of logical CPU cores - 1

In addition, a simpler and coarser determination of the CPU is performed using only the information listed above under version information (1/eax). It is provided as (simple synth) under version information (1/eax). However, it tends to be unable to distinguish between various modern CPUs.

OPTIONS

cpuid accepts the following command line arguments:

-1, --one-cpu: Display information only for the first CPU. This cuts down on the output on a multiprocessor system, and is useful when certain that all CPUs are identical.
-f FILE, --file=FILE: Read raw hex information from FILE instead of from executions of the cpuid instruction.
-h, -H, --help: Display help information.
-i, --inst: Use the CPUID instruction. The information it provides is reliable. It is not necessary to be root to use this option. (This option is the default.)
-k, --kernel: Use the CPUID kernel module. The information does not seem to be reliable on all combinations of CPU type and kernel version. Typically, it is necessary to be root to use this option.
-r, --raw: Display only raw hex information with no decoding.
-v, --version: Display cpuid version.

LIMITATIONS

There are numerous cases where there is no way to distinguish between various CPUs in the (synth) information. In some cases, the sizes of caches, number of cores, brand strings, etc., can be used to distinguish multiple CPUs with the same family and model. But there are cases where that information is insufficient. Whenever cpuid is unable to distinguish between multiple CPUs, it will list all known possibilities.

If you believe that a certain processor should be distinguishable from another and it isn't, please inform the author of this tool.

The (multi-processing synth) information is unreliable on many processors. It faithfully reports the information provided by the CPUID instruction and decodes it as recommended by the processor manufacturers, but often that information is incorrect. The information seems to indicate the architecture's capabilities, rather than what the particular chip actually does. In particular, it seems commonplace to claim the presence of multiple hyperthreads when there is only one.

INFORMATION SOURCES

Information on the CPUID instruction and on specific CPUs is available from the following documents from Intel Corporation <http://www.intel.com/support/processors/index.htm>, with the specified Document Numbers:

: 241618: Intel Processor Identification and the CPUID Instruction, Application Note 485
242480: Pentium Processor Specification Update
242689: Pentium Pro Processor Specification Update
243326: 60- and 66-MHz Pentium Processor Specification Update
243337: Intel Pentium II Processor Specification Update
243748: Intel Celeron Processor Specification Update
243776: Intel Pentium II Xeon Processor Specification Update
243887: Mobile Intel Pentium II Processor Specification Update
244444: Mobile Intel Celeron Processor at 466 MHz, 433 MHz, 400 MHz, 366 MHz, 333 MHz, 300 MHz, and 266 MHz Specification Update
244453: Intel Pentium III Processor Specification Update
244460: Intel Pentium III Xeon Processor Specification Update
245306: Mobile Intel Pentium III Processor and Mobile Intel Pentium III Processor-M Specification Update
245421: Mobile Intel Celeron Processor (0.18u and 0.13u) Specification Update
249199: Intel Pentium 4 Processor Specification Update
249678: Intel Xeon Processor Specification Update
250721: Mobile Intel Pentium 4 Processor-M Specification Update
251309: Mobile Intel Celeron Processor on .13 Micron Process in Micro-FCPGA Package Specification Update
252665: Intel Pentium M Processor Specification Update
253176: Mobile Intel Pentium 4 Processor with 533 MHz System Bus Specification Update
253666: 64 and IA-32 Architectures Software Developer's Manual Volume 2A: Instruction Set Reference, A-M.
276613: Detecting Multi-Core Processor Topology in an IA-32 Platform by Khang Nguyen and Shihjong Kuo
290741: Intel Xeon Processor MP Specification Update
290749: Intel Celeron Processor in the 478-Pin Package Specification Update
300303: Intel Celeron M Processor Specification Update
302209: Intel Pentium M Processor on 90nm Process with 2-MB L2 Cache Specification Update
302352: Intel Pentium 4 Processor on 90 nm Process Specification Update
302354: Intel Celeron D Processor 3xx Sequence Specification Update
302402: Intel Xeon Processor with 800 MHz System Bus
302441: Mobile Intel Pentium 4 Processor supporting Hyper-Threading Technology on 90-nm process technology Specification Update
306752: 64-bit Intel Xeon Processor MP with 1 MB L2 Cache Specification Update
306757: 64-bit Intel Xeon Processor MP with up to 8 MB L3 Cache Specification Update
306832: Intel Pentium Processor Extreme Edition and Intel Pentium D Processor Specification Update
309159: Dual-Core Intel Xeon Processor 2.80 GHz Specification Update
309222: Intel Core Duo Processor and Intel Core Solo Processor on 65 nm Process Specification Update
309627: Dual-Core Intel Xeon Processor 7000 Sequence Specification Update
311827: Intel Celeron D Processor 300 Sequence Specification Update
313065: Dual-Core Intel Xeon Processor 5000 Series Specification Update
313279: Intel Core 2 Extreme Processor X6800 and Intel Core 2 Duo Desktop Processor E6000 Sequence Specification Update
313356: Dual-Core Intel Xeon Processor 5100 Series Specification Update
314554: Dual-Core Intel Xeon Processor 7100 Series Specification Update
314916: Dual-Core Intel Xeon Processor 3000 Series Specification Update
313515: Intel Pentium Dual-Core Processor Specification Update
316134: Quad-Core Intel Xeon Processor 3200 Series Specification Update
316964: Intel Celeron Processor 400 Series Specification Update
316982: Intel Pentium Dual-Core Desktop Processor E2000 Series Specification Update
317667: Intel Celeron Processor 500 Series Specification Update
318081: Intel Xeon Processor 7200 and 7300 Series Specification Update
318547: Intel Celeron Processor 200 Sequence Specification Update
318585: Intel Xeon Processor 5400 Series Specification Update
318586: Intel Xeon Processor 5200 Series Specification Update
318727: Intel Core 2 Extreme Processor QX9000 Series and Intel Core 2 Quad Processor Q9000, Q9000S, Q8000, Q8000S Series Specification Update
318733: Intel Core 2 Duo Processor E8000 and E7000 Series Specification Update
318915: Intel Core 2 Duo Processor and Intel Core 2 Extreme Processor on 45-nm Process Specification Update
318925: Intel Celeron Dual-Core Processor E1000 Series Specification Update
319006: Dual-Core Intel Xeon Processor 3100 Series Specification Update
319007: Quad-Core Intel Xeon Processor 3300 Series Specification Update
319129: Intel Core 2 Extreme Processor QX9775 Specification Update
319433: Intel Architecture Instruction Set Extensions Programming Reference
319536: Intel Atom Processor Z5xx Series Specification Update
319735: Intel Celeron Dual-Core Processor T1x00 Series Specification Update
319978: Intel Atom Processor 200 Series Specification Update
320047: Intel Atom Processor N270 Series Specification Update
320121: Intel Core 2 Extreme Quad-Core Mobile Processor, Intel Core 2 Quad Mobile Processor, Intel Core 2 Extreme Mobile Processor, Intel Core 2 Duo Mobile Processor, Intel Core 2 Solo Mobile Processor and Intel Celeron Processor on 45-nm Process Specification Update
320257: Intel EP80579 Integrated Processor Product Line Specification Update
320336: Intel Xeon Processor 7400 Series Specification Update
320468: Intel Pentium Dual-Core E6000 and E5000 Series Specification Update
320529: Intel Atom Processor 300 Series Specification Update
320767: Intel Core i7-900 Mobile Processor Extreme Edition Series, Intel Core i7-800 and i7-700 Mobile Processor Series Specification Update
320836: Intel Core i7-900 Desktop Processor Extreme Edition Series and Intel Core i7-900 Desktop Processor Series Specification Update
321324: Intel Xeon Processor 5500 Series Specification Update
321333: Intel Xeon Processor 3500 Series Specification Update
322166: Intel Core i7-800 and i5-700 Desktop Processor Series Specification Update
322373: Intel Xeon Processor 3400 Series Specification Update
322568: Intel Celeron Processor E3x00 Series Specification Update
322849: Intel Atom Processor N400 Series Specification Update
322861: Intel Atom Processor D400 Series (Single Core) Specification Update
322862: Intel Atom Processor D500 Series (Dual Core) Specification Update
322814: Intel Core i7-600, i5-500, i5-400 and i3-300 Mobile Processor Series Specification Update
322911: Intel Core i5-600, i3-500 Desktop Processor Series and Intel Pentium Processor G6950 Specification Update
323056: Intel Xeon Processor L3406 Specification Update
323179: Intel Core i7-660UE, i7-620LE/UE, i7-610E, i5-520E, i3-330E and Intel Celeron Processor P4505, U3405 Series Datasheet Addendum Specification Update
323105: Intel Xeon Processor C5500/C3500 Series Specification Update
323254: Intel Core i7-900 Desktop Processor Extreme Edition Series and Intel Core i7-900 Desktop Processor Series on 32-nm Process Specification Update
323338: Intel Xeon Processor 3600 Series Specification Update
323344: Intel Xeon Processor 7500 Series Specification Update
323372: Intel Xeon Processor 5600 Series Specification Update
323874: Intel Pentium P6000 and U5000 Mobile Processor Series Specification Update
324209: Intel Atom Processor E6xx Series Specification Update
324341: Intel Atom Processor N500 Series Specification Update
Intel 64 Architecture Processor Topology Enumeration (Whitepaper)
324456: Intel Celeron Mobile Processor P4000 and U3000 Series Specification Update
324643: 2nd Generation Intel Core Processor Family Desktop Specification Update
324827: 2nd Generation Intel Core Processor Family Mobile Specification Update
325122: Intel Xeon Processor E7-8800 / 4800 / 2800 Product Families Specification Update
325307: Intel Atom Processor Z600 Series Specification Update
325462: Intel 64 and IA-32 Architectures Software Developer's Manual Combined Volumes: 1, 2A, 2B, 2C, 3A, 3B, and 3C
325630: Intel Atom Processor Z6xx Series Specification Update
326140: Intel Atom Processor N2000 and D2000 Series Specification Update
326198: Intel Core i7 Processor Family for the LGA-2011 Socket Specification Update
326510: Intel Xeon Processor E5 Family Specification Update
326766: Desktop 3rd Generation Intel Core Processor Family Specification Update
326770: Mobile 3rd Generation Intel Core Processor Family Specification Update
326774: Intel Xeon Processor E3-1200 v2 Product Family Specification Update
328205: Intel Xeon Phi Coprocessor x100 Product Family Specification Update
328899: Desktop 4th Generation Intel Core Processor Family Specification Update
328903: Mobile 4th Generation Intel Core Processor Family Specification Update
328908: Intel Xeon Processor E3-1200 v3 Product Family Specification Update
329460: Intel Atom Processor C2000 Product Family Specification Update
330785: Intel Xeon Processor E5 v3 Product Family Specification Update
330836: Intel Core M Processor Family Specification Update
330841: Intel Core i7 Processor Family for LGA2011-v3 Socket Specification Update
332054: Intel Xeon Processor D-1500 Product Family Specification Update
332067: Intel Atom Z8000 Processor Series Specification Update
332095: Intel N-Series Intel Pentium Processors and Intel Celeron Processors Specification Update
332317: Intel Xeon Processor E7 v3 Product Family Specification Update
332381: Mobile/Desktop 5th Generation Intel Core Processor Family Specification Update

Information on the CPUID instruction and on specific CPUs is available from the following documents from Advanced Micro Devices, Inc. <http://www.amd.com/us-en/Processors/TechnicalResources>, with the specified Publication Numbers:

: 20734: AMD Processor Recognition Application Note
21266: AMD-K6 Processor Revision Guide Model 6
21641: AMD-K6-2 Processor Revision Guide Model 8
21846: AMD-K6 Processor Revision Guide Model 7
22473: AMD-K6-III Processor Revision Guide Model 9
23614: AMD Athlon Processor Model 4 Revision Guide
23865: AMD Duron Processor Model 3 Revision Guide
24332: AMD Athlon Processor Model 6 Revision Guide
24806: AMD Duron Processor Model 7 Revision Guide
25481: CPUID Specification
25703: AMD Athlon Processor Model 8 Revision Guide
25759: Revision Guide for AMD Athlon 64 and AMD Opteron Processors
26094: BIOS and Kernel Developer's Guide for AMD Athlon 64 and AMD Opteron Processors
27532: AMD Athlon Processor Model 10 Revision Guide
31177H: AMD Geode NX Processors Data Book
31610: Revision Guide for AMD NPT Family 0Fh Processors
33234F: AMD Geode LX Processors Data Book
41322: Revision Guide for AMD Family 10h Processors
41788: Revision Guide for AMD Family 11h Processors
44739: Revision Guide for AMD Family 12h Processors
47534: Revision Guide for AMD Family 14h Models 00h-0Fh Processors
48063: Revision Guide for AMD Family 15h Models 00h-0Fh Processors
48931: Revision Guide for AMD Family 15h Models 10h-1Fh Processors
51810: Revision Guide for AMD Family 16h Models 00h-0Fh Processors

Information on the CPUID instruction and on specific CPUs is available from the following documents from Transmeta Corporation <http://www.transmeta.com/crusoe_docs/Crusoe_CPUID_5-7-02.pdf>:

: Processor Recognition, 2002/05/07

Information on generic hypervisor CPUID levels is available from this proposal: <http://lwn.net/Articles/301888/>.

Information on KVM hypervisor CPUID levels is available from the Linux kernel under Documentation/kvm/cpuid.txt.

Information on Microsoft hypervisor CPUID levels is available from the following document from Microsoft: <http://msdn.microsoft.com/en-us/library/windows/hardware/ff542428%28v=vs.85%29.aspx>.

Also, information is available from the following web sites:

: <http://www.sandpile.org/ia32/cpuid.htm>
<http://en.wikipedia.org/wiki/List_of_Intel_microprocessors>
<http://en.wikipedia.org/wiki/List_of_AMD_microprocessors>
<http://en.wikipedia.org/wiki/Category:X86_microprocessors>

AUTHOR

Todd Allen <cpuid [at] etallen.com>