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Re: rtVAX300 .. adding an CPU Type..
> I've looked closer at the two Memory SIMMs that are on that rtVAX300
> Board. [...] So the entire memory is 4MB + 16bit Parity.
> Is that enough to run a NetBSD kernel over NFS?
Probably. I don't know whether it'll run modern (whatever that means)
NetBSD/vax, but at worst you'll need to work on an older version. I'm
fairly sure there'd be space for the 1.4T I run on those of my machines
that I can, for example...but maybe not for a whole lot more. I recall
running 1.4T on a 5MB hp300 machine, and, while it ran, there wasn't
much RAM left for user processes.
> The rtVAX 300 implements the full VAX memory management [...]
Okay, so we don't have to worry about KA620-style issues; the existing
VAX pmap should work fine.
> 126.96.36.199. Translation Buffer
> To reduce the overhead associated with translating virtual addresses
> to physical addresses, the rtVAX 300 processor employs a 28-entry,
> fully associative translation buffer [...]
> ...whatever this means...
Not much, from a programmer's perspective. As I read it, it just means
you have to be careful to use TBIA and/or TBIS whenever you change
PTEs, which is something I would certainly hope every version of
NetBSD's VAX pmap already does.
I can go into more detail if you like, but, in short, I don't think
this is anything you need to care about.
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