Re: Probing nubus cards

Subject: Re: Probing nubus cards
From: "David A. Gatwood" <email@hidden>
Date: Sun, 28 Jan 2001 17:20:55 -0800 (PST)

On Sun, 28 Jan 2001, Per Ola Ingvarsson wrote:

> On Sun, 28 Jan 2001, David A. Gatwood wrote:
>
> > It doesn't work because I couldn't find a way to io_map memory and then
> > remove the mappings, which is required for NuBus to work. Feel free to
> > look into that. :-)
>
> Blargh! I had hoped that it was my code that didn't work. Hmm, maybe I can
> take a look at it, but I would guess that I'd have to look at it for a
> very long time if even you can't find out how to do it.
>
> Why does it need to unmap the memory and why doesn't pci need that?

It's just the way that the NetBSD nubus code works. It maps one chunk at
a time, then releases it. I had tried at one point to io_map the whole
block, but it resulted in taking up all the page table entries in the
kernel, causing some rather spectacular crashes. Granted, mapping the
whole range is probably not necessary. There's probably some easy way to
map and unmap that I just haven't found yet, but that summer ended and I
haven't had time to look at it again since.

David

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