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Date:      Mon, 21 Sep 1998 00:16:37 +0200
From:      Eivind Eklund <eivind@yes.no>
To:        "Justin T. Gibbs" <gibbs@narnia.plutotech.com>
Cc:        hackers@FreeBSD.ORG
Subject:   Re: malloc()ing 64K physically contiguous buffer in kernel
Message-ID:  <19980921001637.40216@follo.net>
In-Reply-To: <199809202203.QAA03178@narnia.plutotech.com>; from Justin T. Gibbs on Sun, Sep 20, 1998 at 04:03:22PM -0600
References:  <199809201745.NAA21711@skynet.ctr.columbia.edu> <199809202203.QAA03178@narnia.plutotech.com>

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On Sun, Sep 20, 1998 at 04:03:22PM -0600, Justin T. Gibbs wrote:
> In article <19980920212910.21253@follo.net> you wrote:
> > On Sun, Sep 20, 1998 at 01:45:24PM -0400, Bill Paul wrote:
> >> So: is there some way to allocate 64K of contiguous memory? Or even
> >> 8/16/32K? As long as I can hit one of the allowed buffer sizes I'll
> >> be happy, although I wanted 64K in order to reduce the likelyhood of
> >> receiver overruns.
> > 
> > contigmalloc().
> 
> You should use bus_dma instead of contigmalloc, but I won't think
> badly of you until I've gotten off my duff and written the man
> pages for it. (bus_dma eventually uses contigmalloc to satisfy the
> request, but this may change (very likely on other platforms)).

Speaking of this - what is the relationship between the bus_space
stuff you've brought in from NetBSD, and the bus framework dfr has
made for the alpha port?

I have understood it as if they are at slightly different levels, but
I still don't know what to use where (I need to use some bus
abstraction for some work on the Bt848 driver in the not too distant
future (should be past), and don't really know how I'm supposed to go
forward to get this to be "right" - it is an i2c bus, which suggest it
should be integrated with the iic-framework, but from my viewpoint as
writing kernel code for it, it looks like there should be a
NetBSD-style bus_space around it, too...)

How far is what you've written from the NetBSD original?  Can I get by
with using their docs, or is will this make me take a wrong turn?

Eivind.

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