Subject: Re: Preliminary work on ath(4)
To: Bruce J.A. Nourish <>
From: Frank van der Linden <>
List: current-users
Date: 08/20/2003 14:00:37
On Tue, Aug 19, 2003 at 08:27:41PM -0700, Bruce J.A. Nourish wrote:
> I've done some initial work on porting FreeBSD's ath(4). Note that I
> say "initial": I've never done any kernel programming before, everything
> I did I learned tonight. The code is probably not of a very high quality.
> I'm throwing it out here because (a) I'm exhausted and (b) I've hit a
> a wall.

Oon FreeBSD and NetBSD bus_dma, what you do is basically
the following:

	* FreeBSD creates bus_dma tags from parent tags, and stores
	  some parameters in them. We don't do that. Just use the
	  bus_dma tag passed in through the attach argument structure.
	  But, remember some of the parameters passed to the FreeBSD
	  bus_dmatag_create call, they are used in some NetBSD
	  bus_dma calls explicitly (where FreeBSD only passes the tag)

	* The callback function for the bus_dmamap_load function in
	  FreeBSD: just inline the callback function from the FreeBSD
	  source directly after the bus_dmamap_load call in NetBSD.

Those are the basics, I've done it a few times, it isn't so hard to do.

- Frank