VAX Unix System V.2.2 Region Problem

[Mark Campbell]

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