On Tue, 24 Apr 2012 09:15:05 -0500 Tom Marchant <[email protected]> wrote:
:>On Tue, 24 Apr 2012 16:23:50 +0300, Binyamin Dissen wrote: :>>If the "invalid" page can be paged-in, in what way is it "invalid"? :>Bit 53 of a page table entry is the Page-invalid bit. If it is set in :>the page table entry that is used to reference a location in :>storage, a Page-translation exception, PIC 11 (commonly known :>as a "page fault") is recognized. :>Similarly, bit 58 of the segment table entry is the Segment-invalid :>bit. If it is set in the segment table that is used to reference the :>page table needed to reference a location in storage, a :>Segment-translation exception (PIC 10) is recognized. :>There are similar "invalid" bits in bit 58 of each of the three levels :>of region tables. :>It is more common for these exceptions to be resolved and the :>instruction retried than it is for the access to result in a S0C4 abend. As I specified "page in", it is clear that the hardware received an exception. But I would suggest that most references to "invalid" pages do not cause an 0C4. -- Binyamin Dissen <[email protected]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
