With the 6654 shortage, the goal is to differentiate in the SW the 6657 and the 6654.
The DEVSPEED register does distinguish a 6654 from a 6655 because they have a different max frequency, but the 6657 has an 850 MHz version like the 6654 and a 1.25 GHz version like the 6655.
In the post e2ev here :
The user relies on a reserved area of the DEVSPEED register to distinguish a 6657. How can we do it properly to distinguish a 6657? We need information on the number of cores present (but not the DNUM because in all cases only one core is used)