Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!mit-eddie!killer!elg
From: elg@killer.DALLAS.TX.US (Eric Green)
Newsgroups: comp.sys.amiga.tech
Subject: Re: A2090 SCSI vs Video contention - here we go again!
Message-ID: <6499@killer.DALLAS.TX.US>
Date: 20 Dec 88 07:31:11 GMT
References: <14146@oberon.USC.EDU>
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 37

in article <14146@oberon.USC.EDU>, papa@pollux.usc.edu (Marco Papa) says:
> In article <5496@cbmvax.UUCP| andy@cbmvax.UUCP (Andy Finkel) writes:
> |I have a couple suggestions; first, are you running FastMemFirst
> |before mounting your fast file system partitions ?
> My question is as follows:  what if you've one of the "autoboot" devices
> like the GVP board or the A2090A? With the GVP one can have a single
> partition, ALL of it FFS and still boot from it.  So the FFS is up 
> even before FastMemFirst can ever be run.

Note that the GVP is NOT a DMA hard disk controller, so it doesn't
much matter. Video contention is only a problem with DMA to chip or
"half-fast".  

> |    step 2: add a MASK=#007FFFFF
> |	to the mountlist entries of your fastfilesystem partitions.
> 
> I guess in my case, I can only do Step 2. Is that enough to avoid all the
> problems?

Step 2 is useless without step 1, because the FFS has allocated its
buffers in the "half-fast" RAM (since it's first on the free memory
list for "fast" RAM). Thus, when you make accesses into "fast", data
goes to "fast", when you make accesses into "slow", data goes into
"slow" -- with or without the MASK. Don't even bother -- all it does
is add an additional block move, when using a non-DMA controller and
no "fastmemfirst".

BUT, you might want to ask GVP about their autoboot code... it MAY do
an equivalent to "fastmemfirst". In which case your MASK WOULD be
useful, if only to avoid having the CPU thrash around in "chip" when
it could be thrashing around in "fast".

--
Eric Lee Green    ..!{ames,decwrl,mit-eddie,osu-cis}!killer!elg
          Snail Mail P.O. Box 92191 Lafayette, LA 70509              
Netter A: In Hell they run VMS.
Netter B: No.  In Hell, they run MS-DOS.  And you only get 256k.