Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!ukc!slxsys!ibmpcug!gmurray From: gmurray@ibmpcug.co.uk (G Murray) Newsgroups: comp.windows.ms,connect.audit Subject: Paging of non-windows applications Message-ID: <1991May12.203857.9846@ibmpcug.co.uk> Date: 12 May 91 20:38:57 GMT Organization: The IBM PC User Group, UK. Lines: 46 Sorry if this has been asked before, but I haven't been reading this group for long. In 386 enhanced mode, windows 3 implements virtual memory using hardware paging. However, when attempting to run a non-windows application it seems to require enough contiguous physical memory for the application to run. Also the delays and disk accesses that can occur when switching between non-windows applications seems to indicate that the whole Virtual 8086 VM is swapped as one unit, either all in RAM or all swappped out. So, is there any reason why windows doesn't page non-windows applications? I have read the Intel 80386 manuals and can see nothing that would indicate that a V8086 VM can't use paging. The way that I understand that it would work would be that if the Real Mode application (in the V8086 VM) attempts to access a memory location that is not present in RAM, a page fault exception is generated, which is serviced by the Protected mode code in the same way as a page fault occuring in a protected mode (ie windows) application. The page is then brought into memory and following the IRET from the exception handler, the Real mode application continues as if nothing had happened. As I understand it, the one thing that must never be paged is the page fault exception handler. Have I misunderstood the way that paging and page faults are handled in Virtual 8086 mode? If I haven't misunderstood it, then is there some other reason why Windows cannot allow a non-windows application to be paged? ---------------------------------------------------------------------- Graham Murray Email gmurray@ibmpcug.co.uk Senior Programmer OR gmurray@cix.compulink.co.uk Gravatom Technology Ltd Voice +44 329 823986 ---------------------------------------------------------------------- -- Automatic Disclaimer: The views expressed above are those of the author alone and may not represent the views of the IBM PC User Group. --