This RFC patch is intended to allow bypass CPUID, MSR and QuickPIT calibration methods should the user desire to.
The current ordering in ML x86 tsc is to calibrate in the order listed above; returning whenever there's a successful calibration. However there are certain BIOS/HW Designs for overclocking that cause the TSC to change along with the max core clock; and simple 'trusting' calibration methodologies will lead to the TSC running 'faster' and eventually, TSC instability.
I only know that there's a use-case for me to want to be able to skip CPUID calibration, however I included args for skipping all the rest just so that all functionality is covered in the long run instead of just one use-case.