Event queue management

A queue storage 18 stores a queue of event entries corresponding to notification of events from a source to a destination, for example event entries from a hardware event detector (10 in figure 1) that are to be communicated to a software event handler (17 in figure 1). A comparator 22 compares a received event entry with at least one previously received event entry to detect a match, and if a match is detected an event entry merging unit 28 merges the received event entry with the previously received one. The comparison between the event entries may take place in an event register 20 that stores unqueued events yet to be added to the queue storage 18, and the merging may comprise setting a merged entry bit and discarding the newly received event entry. If the queue storage 18 is empty, then the event register 20 and the comparator 22 can be bypassed, so that any currently unqueued event within the event register 20 is be stored into the queue storage 18. The event entries may be translation error event entries in a system which translates between virtual addresses and physical addresses.