How to use the command cpuid (with examples)

The cpuid command is used to display detailed information about the CPUs in a system. It provides information such as the CPU vendor, family, model, and various feature flags. This command can be useful for troubleshooting CPU-related issues, understanding the capabilities of the CPUs in a system, or simply obtaining detailed CPU information.

Use case 1: Display information for all CPUs

Code:

cpuid

Motivation:

Sometimes it’s important to have a comprehensive understanding of all the CPUs in a system. This information can help in diagnosing performance issues or in making decisions regarding system upgrades or optimizations. By using the cpuid command without any arguments, we can easily obtain detailed information about all CPUs in the system.

Explanation:

The cpuid command without any arguments displays information for all CPUs in the system.

Example output:

Processor 1:
  Vendor ID: GenuineIntel
  Processor name: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
  Family: 6, Model: 158, Stepping: 10
  ...
  
Processor 2:
  Vendor ID: GenuineIntel
  Processor name: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
  Family: 6, Model: 158, Stepping: 10
  ...
  
Processor 3:
  Vendor ID: GenuineIntel
  Processor name: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
  Family: 6, Model: 158, Stepping: 10
  ...
  
...

Use case 2: Display information only for the current CPU

Code:

cpuid -1

Motivation:

In some cases, we may only be interested in obtaining detailed information about the current CPU. This can be useful when diagnosing specific CPU-related issues or when performing optimizations that only apply to the currently active CPU.

Explanation:

The cpuid -1 command displays information only for the current CPU.

Example output:

Processor:
  Vendor ID: GenuineIntel
  Processor name: Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
  Family: 6, Model: 158, Stepping: 10
  ...

Use case 3: Display raw hex information with no decoding

Code:

cpuid -r

Motivation:

Sometimes, it may be necessary to obtain the raw hex information provided by the CPU’s CPUID instruction without any decoding. This can be useful for advanced debugging or when analyzing low-level CPU information that requires manual interpretation.

Explanation:

The cpuid -r command displays raw hex information with no decoding.

Example output:

Processor 1:
  Raw hex data: 0x00000001 0x007BFEBB 0xFF08E3FD 0xBFE9FBFF
  
Processor 2:
  Raw hex data: 0x00000001 0x007BFEBB 0xFF08E3FD 0xBFE9FBFF
  
Processor 3:
  Raw hex data: 0x00000001 0x007BFEBB 0xFF08E3FD 0xBFE9FBFF
  
...

Conclusion:

The cpuid command is a valuable tool for obtaining detailed information about the CPUs in a system. Whether we need to understand the capabilities of the CPUs, troubleshoot issues, or perform low-level analysis, the cpuid command provides a convenient way to access important CPU information.