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pc532@bungi.com (pc532@bungi.com) (08/15/90)

GatorMail-Q                   Minix

Especially if you have 8 MB memory, I suggest that you increase the
size of the disk cache in the Minix kernel (NR_BUFS in fs/const.h).  I
changed the size to 2048 and the speed of compilation when making a
Makefile increased drastically. 

With a small cache most of the time in a compilation was spent in
reading the compiler and the like into memory. When the cache is large
enough the compilation times are comparable to a sparc or similar. On
the other hand it makes it more important to say sync before halting.

It probably is a good idea to increase the size of the related hash
table (NR_BUF_HASH (I use 1024)). 256 (NR_BUFS) and 128 seemed
reasonable with 4MBs.  
Some other numbers I increased without problems: 
- number of processes (16 -> 128) NR_PROCS in h/const.h 
- number of superblocks (5 -> 32) NR_SUPERS in fs/const.h

It is funny how most of the numbers seem somewhat underdimensioned
when there are 8 MBs of memory, 1.4GB of disk, and around 10 MIPS in a
Minix system :-), as we had at one time.

	Johannes



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From: jvh@robin.hut.fi
To: pc532@bungi.com
Subject: Minix
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pc532@bungi.com (pc532@bungi.com) (09/18/90)

GatorMail-Q                   Running without an FPU
I've had to struggle a bit, but I've managed to get MINIX up on my pc532
without an FPU. Some of the problems I encountered are:

* The ROM needed a fix to get RUN and STEP to work.
* MINIX saves FPU registers on a task switch
* _begsig also saves FPU registers, causing any process which intercepts
  signals to dump core.
* GCC uses floating point operations in global-alloc.c

So far I've been able to fix these problems in an ad-hoc manner, but I'd 
like to co-ordinate efforts with other FPU-less pc532 owners (if there are
any).

I have several questions for the NS32K wizards out there:

1) Is there some way to reliably detect the physical presence or absence 
   of an FPU?
2) Is there any way a user process can read the state of the F bit in 
   the CFG register, given that SPRi CFG,Rn is a privileged instruction?
3) Are there any free (or nearly so) floating point emulation libraries 
   for the NS32000 series? 
4) Are there other traps I haven't stumbled into yet?
	-bert



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From: Robert D. Vincent <bert@Shiva.COM>
To: pc532@bungi.com
Subject: Running without an FPU
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