campbell@sauron.UUCP (Mark Campbell) (04/21/86)
Note: This request concerns VAX Unix V.2.2 kernel source. If you don't have it, then you're probably not going to be interested. I need some help understanding a small piece of VAX Unix V.2.2 kernel source. Unfortunately, I don't have a VAX (any more) to help me test any theories I might have. In the kernel's "procdup" routine, called from "newproc" to duplicate the process, the routine "dupreg" is asserted to duplicate the regions of the process. The problem I am having concerns the udot area. When "dupreg" is asserted for the udot, it seems like it will (amoung other things): 1) Cause the parent and child udot PTE to be marked as C/W. 2) Cause the paged-referenced count to be incremented for the original udot page. At a later point in this routine, a hand-crafted udot is placed in the child. My questions concerns the aforementioned two points -- what happens to the marked PTE's and the page referenced count? Even if the child's PTE is fixed by the hand-crafting, what about the parents? I would appreciate any replies, either E-mailed or posted. Disclaimer: NCR is in no way responsible for this request. -- Mark Campbell Phone: (803)-791-6697 E-Mail: !ncsu!ncrcae!sauron!campbell