Subject: Re: Virtual Memory Subsystem
To: Charles M. Hannum <>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: port-i386
Date: 11/26/1996 09:20:28 (Charles M. Hannum) writes:

[Jonathan Stone wrote:]
>> OpenBSD has a fix. It's sub-optimal but perhaps we could use it
>> until a _real_ fix of the VM system is done?

>Their `fix' will occasionally remove an object that another object is
>pointing to, causing stray pointer references.  We were, in fact,
>working with Niklas to fix this, but he apparently decided it wasn't
>important enough to get it right, and punted.

If I've followed this correctly, the OpenBSD fix:

	i) collapses shadow-copy object chains by copying
	   swap pages from one object to another, (i.e., involving paging
	   and copying), and

       ii) has bugs in doing so that can leave danging VM-object 

If so, I withdraw the suggestion that we incorporate it.
(I was aware of the first but not the second.)