Subject: Re: G4 upgrade and six slot macs
To: <>
From: Kevin Diggs <kevdig@rcn.com>
List: port-macppc
Date: 02/20/2002 10:19:46
Donald,

    I believe what you are referring to is speculative accessing. I am
talking about something different. Something having to do with two bandits
in the beast?

                    kevin

P.S.:    I read in an faq somewhere that the 8600 and 9600 were
speculative access clean. I have a powerlogix g3/500 in my 8600 and
routinely turn on speculative accessing in the cache controller thingy.
Once I discovered that you NEVER use quicktime to encode video if you have
run netscape (always reboot), it is fairly stable.

Donald Lee wrote:

> >Hi,
> >
> >    This may be a little off topic, but has anybody heard of potential
> >problems with some G4 upgrades and the six-slot macs (aka 9500/9600)?
> >Something to do with illegal bus states and cpu cache snoop getting
> >interrupted resulting in cache coherency problems?
> >
> >                    kevin
>
> Many moons ago, when the G3 upgrades came out, there were problems
> with MacOS because the out-of-order memory refs from the G3 could
> touch the HW space.  The MacOS/ROMs that were pre-G3
>  knew nothing about this and did not
> set the "guard bit" on this address space, so things got flaky.
>
> This should not be a problem with NetBSD.
>
> -dgl-