| .. SPDX-License-Identifier: GPL-2.0+ | |
| .. index:: | |
| single: cpuid (command) | |
| 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. | |
| 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 |