cpuid command

Synopsis

cpuid <op>

Description

The cpuid command requests CPU-identification information on x86 CPUs. The operation <op> selects what information is returned. Up to four 32-bit registers can be update (eax-edx) depending on the operation.

Configuration

The cpuid command is only available on x86.

Return value

The return value $? is 0 (true).

Example

=> cpuid 1
eax 00060fb1
ebx 00040800
ecx 80002001
edx 178bfbfd

This shows checking for 64-bit ‘long’ mode:

=> cpuid 80000000
eax 8000000a
ebx 68747541
ecx 444d4163
edx 69746e65
=> cpuid 80000001
eax 00060fb1
ebx 00000000
ecx 00000007
edx 2193fbfd   # Bit 29 is set in edx, so long mode is available

On a 32-bit-only CPU:

=> cpuid 80000000
eax 80000004
ebx 756e6547
ecx 6c65746e
edx 49656e69
=> cpuid 80000001
eax 00000663
ebx 00000000
ecx 00000000
edx 00000000   # Bit 29 is not set in edx, so long mode is not available