Date: Tue, 26 Sep 1995 15:01:19 -0700
From: brianh@lexus.West.Sun.COM (Brian Horn)
Subject: Item #291: PPC default mode for map not defined

P1275 Open Firmware Working Group Proposal -- Proposal #291 Ver 1.0

Title:		Specifiy default MMU mode for "map" method

Author:		Brian.Horn@west.sun.com

Date:		09/26/95

Ed/Tech:	Editorial & Technical

Synopsis:	The default MMU mode is left unspecified

Doc & Version:	PowerPC processor binding to IEEE1275-1994 Rev 1.5 draft

Problem:	Using the default MMU mode parameter is impossible

Proposal:	
		In section 7.1 MMU related methods add the following:

		If the mode parameter for the map method is -1 (indication
		the default value ought to be used) then the default
		value shall be W=0 I=0 M=1 G=0 PP=00.

		Further on line 26/27 (the line numbers don't line up).
		the text that reads "mapped by map-in shall be marked
		as Cache-Inhibited, Guarded." should be ammended by
		appending "and Memory-coherent".

		As a side note I would propose an errata to the base
		document (IEEE1275-1994) on page 158 (glossary) w.r.t.
		the method "map".  It states "If mode is -1, an
		implementation-dependant default mode is used."  I propose
		that it be changed to "If all mode cells have the value
		-1, a MMU specific default mode is used."

[ P1275 Item #291 -- Received: Tue Sep 26 14:58:30 PDT 1995 ]