To read 36-bit registers in the Low Latency 10, 40 and 100GbE MAC IP cores, read the lower 32-bit first, followed by upper 4-bit.
For self-clear (RC) counter registers such as register-based counters, the lower 32-bit must be read first, followed by the upper 4-bit to obtain correct values.
For non-self-clear (RO) counter registers such as memory-based counters, when the lower 32-bit are read, the upper 4-bit are captured. Therefore, the misalignment of the lower 32-bit and the upper 4-bit values due to carry to the upper 4-bit during counter read will not happen.