Worth noting that this isn't limited to Windows - for a long time, Linux was specifically checking whether a CPU was an Intel before using the ACPI fixed functi

Worth noting that this isn't limited to Windows - for a long time, Linux was specifically checking whether a CPU was an Intel before using the ACPI fixed function hardware interface for CPU scaling. To be fair, that's partially because the spec actually says that this interface is CPU vendor-defined, but it's probably reasonable to give the benefit of the doubt when they're setting the same cpuid flag. There's a lot of ways to screw up compatibility.