Patent ID: 7047520

Claim:
A method of providing a watchpoint in a computer system, said computer system comprising a paging mechanism including a system page table, said method comprising the steps of: modifying the system page table for a memory page containing a watchpoint, such that a page fault interrupt is triggered when said memory page is accessed; providing a pagepoint table, wherein entries in the pagepoint table correspond to memory pages, and information stored in the pagepoint table defines the watchpoints contained within each page; modifying the paging mechanism of the computer system, so that responsive to a page fault interrupt, a determination is made as to whether said interrupt has been triggered by an access to a watchpoint; and responsive to said determination being positive, passing control to a watchpoint handler, wherein said determination as to whether said interrupt has been triggered by an access to a watchpoint comprises the steps of: testing, based on information stored in an entry in the system page table, whether the page for which the interrupt has been triggered contains any watchpoints, and if not, treating the interrupt as a standard page fault interrupt; and if the page for which the interrupt has been triggered contains a watchpoint, testing, based on information stored in an entry of the pagepoint table corresponding to the entry of the system page table for said interrupt, whether the address for which the interrupt has been triggered matches a watchpoint, and if not continuing with the application; wherein it is determined that the interrupt has been triggered by an access to a watchpoint only if both these tests are positive.