tcwan@umiami.ir.miami.edu (04/16/91)
Thanks to all who replied to my queries about VM, INITs and possible conflicts.
Right now, the only docs which discusses Sys. 7.0 VM that I am aware of are:
about-70-vm.txt -- in the /info-mac/report directory on sumex.
describes briefly the myths and realities about VM and also
reentrant SCSI driver code.
TN 285 -- also at sumex.
describes the GetPhysical Toolbox calls and how VM affects
INITs and other code called at interrupt time.
Inside Mac Vol 6 -- ??
I have not been able to get a hold of it yet. Probably the most
comprehensive documentation available?
Does anyone else have any further details?
I have included their replies below:
From: IN%"lasleyse@wam.umd.edu" "Scott E. Lasley" 12-APR-1991 14:11:35.40
Sorry if I have sent this to you before. I sent this to somebody,
but I don't remember whom. There is a report at sumex-aim.stanford.edu
in the info-mac/report directory from Craig Prouse at Apple dealing
with System 7 VM. I don't know if it goes into as much detail as you
would like, but it may be a start. It is called about-70-vm.txt.
From: IN%"lsr@Apple.com" 12-APR-1991 21:51:48.27
The system guarantees that the entire System Heap is held in physical memory.
Most INITs install things in the System Heap and will work.
The other way INITs allocate memory is by moving BufPtr, but this memory
is not held in physical memory. Such INITs may not work under VM if this
memory is needed at interrupt time.
All this is documented in Tech Note 285.
From: IN%"jyen@apple.com" "John Yen" 14-APR-1991 16:31:45.38
For various reasons, quite a bit of the OS is actually _safer_
with VM on.
The Memory Manager chapter in Inside Mac 6 has a reasonable description
of VM.
John Yen jyen@apple.com 7.0 kernel test team
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