On-chip resources of a serial buffer are accessed using priority packets of a Lite-weight protocol. A priority packet path is provided on the serial buffer to support priority packets. Normal data packets are processed on a normal data packet path, which operates in parallel with the priority packet path. The system resources of the serial buffer can be accessed in response to the priority packets, without blocking the flow of normal data packets. Thus, normal data packets may flow through the serial buffer with the maximum bandwidth supported by the serial interface. The Lite-weight protocol also supports read accesses to queues of the serial buffer (which reside on the normal data packet path). The Lite-weight protocol also supports doorbell commands for status/error reporting.