Re: M68k backend has landed in LLVM - NetBSD support

[John Klos <john%ziaspace.com@localhost>]

> Switching to 8KB pages is extremely simple and provides up to 960MB of 
> virtual address space instead of 224MB; you change PGSHIFT from 12 to 13 
> and do a full rebuild. Here's the diff for hp300:

We've already done that for Amiga and (in current) mac68k. I suppose 
what's next would be to update MAXTSIZ, DFLDSIZ, MAXDSIZ and friends...

> Bitsavers has all of the Motorola manuals online, in 
> <http://www.bitsavers.org/components/motorola/68000/>. You'll want the 
> 68851, 68030, 68040, and 68060 manuals.

I have several of these (M68030, M68060 books), and they're great 
references, but they really don't help with understanding the NetBSD pmap. 
I'm learning, but it's a slow process.

> Probably the simplest possible change beyond switching to 8KB pages 
> would be to increase the size of the root. Even if it's only increased 
> statically (say based on a kernel config parameter -- you aren't going 
> to make use of 4GB of virtual address space on an 8MB system) it doesn't 
> take much to enable vastly more VM.

Increase the size of the root? I don't follow... Would love to hear more, 
though :)

John