A method is provided that allows a general set of watchpoints to be defined for a computer system (a watchpoint is a memory address that triggers an interrupt for debugging or tracing purposes). This is accomplished by modifying the system page table for the memory page containing a watchpoint, such that a page fault interrupt is triggered whenever said memory page is accessed (for example by marking the page as not present). The paging mechanism of the computer system is then adapted, so that responsive to a page fault interrupt, a determination is made as to whether such interrupt has resulted from an access to the watchpoint, and if so, control is passed to a watchpoint handler. Alternatively, if there is no watchpoint, normal paging operations can be resumed if necessary.