On 20/01/2016 15:52, Roman Kagan wrote: > I think Paolo wanted to be compatible not only with the de facto > implementation in Windows Hyper-V guests, but also with the Linux driver > which followed the buggy spec and thought 0xFFFFFFFF to be invalid.
0xFFFFFFFF is not invalid; it means it is valid but you have to use the MSR. With 0, you cannot use the MSR either and Windows will use the ACPI PM timer or similar. You can see the difference from the result of QueryPerformanceFrequency, IIRC. Paolo
