After debuging unstable tsc issue for the BIOS of my company's products, I suspect that tsc may be always unstable when the only other clocksource is jiffies.

I got the error like 
`Clocksource tsc unstable (delta = -531266231 ns).` Then the kernel selected jiffies other than tsc. 
The only two clocksources are tsc and jiffies.
I tried the Linux kernel 2.6 and 3.2 both with i386 and x64. The kernel said that the CPU actually supported constant tsc and invariant tsc. 

After checking the Linux source code, I find that tsc has a flag `CLOCKSOURCE_MUST_VERIFY` while jiffies does not. I guess that if there are only two clocksources, jiffies and tsc, the jiffies will be the clocksource watchdog.
However, compared to tsc, jiffies is a very poor clocksource, and therefore I suspect that tsc at this situation will always be "unstable" because there is a bad watchdog to verify it.

I also check some other system with well working tsc, and find they have other clocksources like Hpet or acpi\_pm.

Therefore, how can I tell whether the tsc instability results from jiffies or some error elsewhere?