Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!usc!apple!jyen
From: jyen@Apple.COM (John Yen)
Newsgroups: comp.sys.mac.system
Subject: Re: Is VM for 030 Macs in S7
Message-ID: <13101@goofy.Apple.COM>
Date: 17 Apr 91 02:44:03 GMT
References: <671469218.0@mmug.mn.org> <1991Apr14.013607.25447@swbatl.sbc.com> <1991Apr14.194137.8329@mintaka.lcs.mit.edu>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 17

Doug Siebert (dbert@wookumz.gnu.ai.mit.edu) writes:
> Your problem is most likely that although you have 30 Meg free, your drive is
> fragmented and 3 Meg is the largest contiguous block you have. Defragment your
> drive and I'll bet you can get more VM.  (Though I think cx's are limited to
> 16M total (virtual + physical) because the ROMs are not 32-bit clean.  Is this
> the case or am I mistaken?

Uh, well, no.  VM does NOT require contiguous free space on the backing store
HD.  The limit is due to the cx's 24-bit ROMs.
The formula (wow, higher math) is:

if 24-bit, possible VM space = 14 - 1/slot occupied
if 32-bit, possible VM space = 1 gigabyte, limited by page table size

Limited by HD free space, of course.

John Yen  jyen@apple.com  7.0 kernel test team