From: adam@microware.com (Adam Goldberg) Subject: Re: DPMI under dosemu (was Re: DOSEMU Success list!!) Date: Tue, 30 Mar 1993 14:08:21 GMT
bsa@kf8nh.wariat.org (Brandon S. Allbery) writes:
>Suffice it to say that VCPI is a pain in the *ss to administer in a
>demand-paging system. Which is why Windows and OS/2 don't support VCPI and
>why (Quarterdeck and Phar Lap aside) it's being replaced by DPMI.
This is almost certainly NOT the reason why VCPI is being replaced by
DPMI. Using VCPI the 'client' and the 'server' become peers after the
client goes into protected mode. Using DPMI, the 'client' is always a
client--to allocate a new GDT entry, for instance, there is a DPMI
call--with VCPI, the 'client' just grabs one.
Paging problems aside, it is impossible to have a secure and protected
OS which supports VCPI--any client may crash the system totally.
Adam
-- Adam G. adamg@microware.com, or ...!uunet!mcrware!adamg The above is not to be construed in any way as the official or unofficial statements of Microware, or any Microware employees.