Re: G3 upgrade L2 cache

[Havard Eidnes <he%NetBSD.org@localhost>]

> >> I just pulled the card.  It's a "Sonnet Crescendo G3" and the
> >> sticker also says "300/512".  [...] assume the 300 is the clock
> >> speed and the 512 is the cache size.  This helps, but still leaves
> >> me wondering what clock ratio to use and which of the L2RAM values
> >> it wants.
> > According to that web page, the 512k cache Crescendo G3's L2 runs at
> > 150 MHz (2:1).
>
> Well, according to that page, there exists a 300MHz Sonnet G3 card with
> 512K of cache running at 150MHz.  Lacking any particular reason to
> think there exist no other Sonnet 300/512 cards, I'd been considering
> this nothing more than a hint - especially since it says "Crescendo
> PCI", and my card is not marked "PCI" as far as I can see.

If I recall correctly, this is a matter of nomenclature.  What I
think this means is that this is a CPU card for a "PCI" MacIntosh
model, where 7600 is one in that family; I beleive this model was
among the first MacIntosh machines to have a PCI bus.

> >> If I get those values set wrong, can it actually fry hardware, or
> >> will it corrupt memory at worst?
> > It'll crash.  There's no chance you'll fry any hardware.
>
> Well, then, I can just try all three L2RAM values and see which one(s)
> work(s).  I feel much less worried about experimenting when a wrong
> guess means the OS crashes, rather than letting the magic smoke out.

Again, to be concrete, I'd suggest, in your case:

# Enable & config 512KB cache on 1/2 speed on G3 300MHz board
options         L2CR_CONFIG="(L2SIZ_512K|L2CLK_20|L2RAM_PIPELINE_BURST)"

I'm just guessing that "Pipeline burst" is correct in your case;
that's what worked with my G3 Sonnet Crecendo 350MHz card in an
identical machine.

Regards,

- Håvard