CPU Config (Intel)
CPUID Function eax=$2
Returned in eax,ebx,ecx,edx

The CPU configuration information is specific to CPU manufacturers.

GenuineIntel CPUs use this space to return information about the L2 cache onboard (you can use this information to differentiate between the Pentium II and the Celeron). For a full sheet

For information about decoding the CPU configuration fields (which includes information about CPU cache size), see this Intel support page:

http://www.intel.ie/support/processors/procid