How to Tell Whether TSCs are Synchronized Across Cores?

How to Tell Whether TSCs are Synchronized Across Cores?

Post here states that new BIOS should synchronize all: Getting cpu cycles
using RDTSC - why does the value of RDTSC always increase?
The kernel source here
(http://lxr.linux.no/#linux+v2.6.38/arch/x86/kernel/tsc.c#L859) states
that "Intel systems are normally all synchronized" but kernel "assumes
multi socket systems are not synchronized".
Is there a way to figure whether TSCs are synchronized across cores AND CPUs?
I refer to the initial value of each TSC after startup.
Any idea?
Thanks.