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Date:      Mon, 02 Oct 2000 14:58:39 +0900
From:      Mitsuru IWASAKI <iwasaki@jp.FreeBSD.org>
To:        msmith@freebsd.org
Cc:        iwasaki@jp.FreeBSD.org, takawata@shidahara1.planet.sci.kobe-u.ac.jp, haro@tk.kubota.co.jp, current@freebsd.org, acpi-jp@jp.FreeBSD.org
Subject:   Re: Interesting AML bug... recommended workaround?
Message-ID:  <20001002145839G.iwasaki@jp.FreeBSD.org>
In-Reply-To: <200010012204.e91M4wJ00361@mass.osd.bsdi.com>
References:  <200010012204.e91M4wJ00361@mass.osd.bsdi.com>

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> Here's what seems to be an interesting AML or AML parser bug.
> 
> 	OperationRegion(PSRG, SystemMemory, 0x0410, 0x1)
> 	Field(PSRG, DWordAcc, NoLock, Preserve) {
> 		,	2,
> 		PS2E,	1
> 	}
> 
> The field is marked for 32-bit access, but the region is only 1 byte 
> wide.  What's the correct thing to do here?  Expand the region to 
> accomodate the field's access requirements?  Constrain the access size of 
> the field to that of the region?

I thought read 32-bit, update target bits, write back whole 32-bit for
updating.  For reading value, read 32-bit and shift & mask bits as well.
I hope I could understand description in Spec 15.2.3.3.1.9; "If desired,
AccessType can be used to force minimum access width."

Thanks


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