Traffic Isolation at a Chip-To-Chip Gateway of a Data Processing System

An apparatus comprising:

• a local request tracker configured to store entries for transaction requests received from a local requesting agent of a first chip;
• a port configured to send link requests to, and receive responses from, a remote agent of a second chip via a link between the first chip and the second chip;
• dispatch logic circuitry, configured to send link requests, based on the transaction requests, to the port;
• and
• a controller configured to:
• in response to an isolation trigger:
• enter an error isolation mode by moving the port into isolation;
• complete in-process transaction requests with entries in the local request tracker for which a link request has been dispatched and no response yet received;
• and
• mark the local request tracker entries as locked and disable allocation of the entries;
• and
• on receiving a response to an in-process transaction request while in the error isolation mode:
• drop the response;
• mark the associated entry as unlocked and enable allocation of the entry;
• and
• complete a new transaction request for the entry by sending a completion response without dispatching the new link request to the port.