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Date:      Tue, 29 May 2012 17:09:22 -0700
From:      "Thomas D. Dean" <tomdean@speakeasy.org>
To:        freebsd-drivers@freebsd.org, phk@FreeBSD.org
Subject:   Re: nanoBSD Driver Build
Message-ID:  <4FC56532.8090802@speakeasy.org>
In-Reply-To: <4FC40922.5030009@speakeasy.org>
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On 05/28/12 16:24, Thomas D. Dean wrote:
> I need to build a (for me) complicated driver for nanoBSD running on an

In this driver for the Elan SC520, I need to access the mmcr registers.
The cpu manual says these registers start at 0xfffef000.

In a driver, elan_mmcr written by phk@FreeBSD.org, the mmap function
returns i386_btop(0xfffef000).

In my driver, I tried to use

lcd_mmcr = (struct elan_mmcr *)0xfffef000
and
lcd_mmcr = (struct elan_mmcr *)i386_btop(0xfffef000);

accessing lcd_mmcr defined either way causes a trap.

How do I access these registers?

Tom Dean
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