公开(公告)号：BR8700178A

公开(公告)日：1987-12-01

申请号：BR8700178

申请日：1987-01-16

Applicant: IBM

Inventor： DUVALL KEITH ELLIOT ,  HOOTEN ANTHONY DANA ,  O'QUIN JOHN CLAUDE III ,  SMITH TODD ALLEN

IPC: G06F9/46 ,  G06F12/08 ,  G06F12/14

Abstract: A method for automatically extending the size of a segment in a page segmented virtual memory data processing system which increases the size of a segment in blocks of 64K virtual pages in response to the system detecting that the requested page has been protected. The conventional UNIX type System Calls create and open files in virtual memory. All pages are protected "read only" until a SHMAT type System Call is made to operate on a page at a specific address. At that point in the process, a protection exception is recognised by the system and the UNIX kernel takes control to remove the protection and update the appropriate data structures to reflect the new status of the page and the addresses in real memory where the page may be found. Segments containing mapped files are also extended by the method.