CPUID Emulation — Intel® SDE documentation

# CPUID Emulation

The CPUID instruction is the main vehicle for software to look for the features of the underline CPU. It returns the processor identification and feature information in the EAX, EBX, ECX, and EDX registers. The instruction’s output is dependent on the contents of the EAX register upon execution (and in some cases, ECX as well).

Intel® SDE emulates the instruction and returns the information as expected from the specified CPU. Intel® SDE is using CPUID definition file to hold the various CPU information. The CPUID definition files are part of the kit, and the right one is used automatically when specifying a CPU knob.

Intel® SDE allow the users to provide their own CPUID definition file, to disable certain features or to enable certain features.

Here is a list of options:

`-cpuid_in`

  CPUID definition file for SDE. This definition in the file suppress the CPUID definition through CPU knob and the two methods can’t be mixed.

`-disable_feature`

  Disable features in CPUID. This knob can be used multiple times. Use the option ‘list’ for getting the list of valid options.

`-enable_feature`

  Enable features in CPUID. This knob can be used multiple times. Use option ‘list’ for getting the list of valid options.

`-update_cpuid_from_host`

  Update specific CPUID leaves from the host [default 1]

`-use_host_cpuid`

  Use host CPUID instead of SDE. [default 0]