Im working on a linux kernel module in which i need to read the cpuid of a processor to see if a feature is present. This issue stems from bios not performing the proper steps during resume to ensure rdrand continues to function properly. Also checks for presence of an 80287 or 80387 coprocessor. The cpuzs detection engine is now available for customized use through the. Processor name and number, codename, process, package, cache levels. Browse the source code of linuxarchx86 linuxarchx86.
The proccpuinfo file contains details about individual cpu cores. Tom lendacky there have been reports of rdrand issues after resuming from suspend on some amd family 15h and family 16h systems. Accesses to this msr are supported when either cpuid eax14h, ecx0. Cpuz is a freeware that gathers information on some of the main devices of your system. Thus, the way to read up on linux topology on x86 is to start with the generic one and look at this one in parallel for the x86 specifics. Cpuid provides an interface for querying information about the x86 cpu. Use flags register, pushpop results, and cpuid instructions to determine cpu type and vendor.
Retrocomputing stack exchange is a question and answer site for vintagecomputer hobbyists interested in restoring, preserving, and using the classic computer and gaming systems of yesteryear. Needless to say, code should use the generic functions this file is only here to document the inner workings of x86 topology. Erp plm business process management ehs management supply chain management ecommerce quality management cmms. Ecxbit2 however i am using the following code to read cpuid. This device is accessed by lseek2 or pread2 to the appropriate cpuid level and reading in chunks of 16 bytes. It was introduced by intel in 1993 when it introduced the pentium and slenhanced 486 processors a program can use the cpuid to determine processor type and whether features. The kernel package contains the linux kernel vmlinuz, the core of any linux operating system. Linux kernel drops support for old intel 386 cpus phoronix.
In the x86 architecture, the cpuid instruction identified by a cpuid opcode is a processor supplementary instruction its name derived from cpu identification allowing software to discover details of the processor. Real time measurement of each cores internal frequency, memory frequency. Cpuz, a windows utility that uses cpuid to identify various system settings. Cpuid 4 linux programmers manual cpuid 4 name top cpuid x86 cpuid access device description top cpuid provides an interface for querying information about the x86 cpu. Cpuid4 linux programmers manual cpuid4 name top cpuid x86 cpuid access device description top cpuid provides an interface for querying information about the x86 cpu. For example, if the program wanted to use special matrixmath instructions available on some cpus, it could check whether the instructions were. Enabling this feature allows processes to access the x86 cpuid instructions needed to execute on a particular cpu through character devices. It supports intel, amd, and via cpus, as well as older transmeta, cyrix, umc, nexgen, rise, and sis cpus. The cpu information includes details about the processor, like the architecture, vendor name, model, number of cores, speed of each core etc.
Is there an easier way to understand the multitude of settings in the kernel. How to read cpuid instruction for each cpu on linux with. On my fedora 19 system i was able to install the package with the following command. Memory type, size, timings, and module specifications spd. Started by thomas gleixner and borislav petkov linux drivers subsequently pokes it, and changes the cpu speed. Redhat display cpu configuration the unix and linux forums. It supports intel, amd, via, hygon, and zhaoxin cpus, as well as older. Intel recommends first checking for the existence of cpuid leaf 1fh before using. Generated on 2019mar29 from project linux revision v5. The cpuid command fetches cpuid information about intel and amd x86 processors. As the name suggests, windows nt4 did not boot properly unless this bit was set, but later versions of windows do not need it, so basic leaves greater than 4 can be assumed visible on current windows systems. Cpuid dumps detailed information about the cpus gathered from the cpuid instruction, and also determines the exact model of cpus. A larger read size means multiple reads of consecutive levels.
Once installed, run cpuid to collect information concerning the x86 cpu. Xen amd64 kernel on debian is i386 howtoforge linux. The lower 32 bits of the file position is used as the incoming %eax, and the upper 32 bits of the file position as the incoming %ecx, the latter intended for counting eax levels like eax4. Browse the source code of linux arch x86 linux arch x86. Cpuz uses a configuration file, i, that allows to set several. Theres a tool called cpuid that one can use to query for much more detailed information than is typically present in lshw or proccpuinfo. Pke to enable protection keys and the rdpkruwrpkru instructions this is because userspace can not see cr4 contents, but it can see cpuid contents. Ingo molnar submitted the nuke 386dxsx support pull request for linux 3. Linux tool to dump x86 cpuid information about the cpus cpuid dumps detailed information about the cpus gathered from the cpuid instruction, and also determines the exact model of cpus. It supports intel, amd, via, hygon, and zhaoxin cpus, as well as older transmeta, cyrix, umc, nexgen, rise, and sis cpus. Contribute to torvaldslinux development by creating an account on github. Dropping the old intel 80386 code is being done to reduce some complexity within the linux kernel to allow for future improvements without having. Amd memory encryption the linux kernel documentation.
Linux tool to dump x86 cpuid information about the cpus. Hi, how to find the cpu configuration details of cores, speed mhz, virtual processors for the following servers. Dec 14, 2015 lscpu command show information on cpu architecture x86info command show x86 cpu diagnostics cpuid command dump cpuid information for each cpu. There are quite a few commands on linux to get those details about the cpu hardware, and here is a brief about some of the commands. In the x86 architecture, the cpuid instruction is a processor supplementary instruction allowing. It supports intel, amd, via, hygon, and zhaoxin cpus, as well as older transmeta, cyrix, umc.
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