Date: Wed, 31 Jan 96 17:30:06 PST
From: mwi@FirmWorks.COM (Mark Insley)
Subject: Item #314: PCI: get-inherited-property bug in Apple OF


P1275 Openboot Working Group Proposal -- Proposal #:314 Ver 1

Title:          More Apple Bug Fixes.

Author:         Mark Insley

Date:           January 31st, 1996

Ed/Tech:        Technical

Synopsis:       Proposal to add additional wording to PCI Bus Binding

Doc & Version:  PCI Bus Bindings to IEEE 1275-1994 Draft 1.5, 20 March 1995

Problem:        The Apple implementation of Open Firmware returns an incorrect
		number of items to the stack when the method "get-inherited-property"
		is executed.

Proposal:       The proposal is to modify the previously added documentation
		regarding map-in functions to include additional text about
		this problem as well.

Overview

   According to the IEEE P1275 Standard, the stack description for get-inherited-
   property is:

	get-inherited-property  ( name-str name-len -- true | prop-addr prop-len false )

   With the current Apple OFW implementation, when a property is found, the prop-len
   is missing from the stack after the call to get-inherited-property. Instead of three
   stack items after a successful call, there are only two, the prop-addr and false.
   
Proposed Solution

   We propose that Apple fix this bug at the same time that the map-in
   problem is fixed as described in proposal #303. And that if they agree
   to make this fix, then the text added to the PCI binding document should
   read as follows:
	
      The method "add-range" is reserved and shall not be implemented in
      future releases of OFW. The presence of this method in the PCI node
      indicates to child nodes both that the "map-in" method of this bus
      node requires the phys.lo address to be extracted from the
      "assigned-addresses" property and that the method
      "get-inherited-property" does not return the "prop-len" (only the
      "prop-addr" and "false") if the property is found.  The non-existence
      of this method indicates to child nodes that the phys.lo address is an
      offset relative to the base address and that "get-inherited-property"
      returns three stack items ("prop-addr" "prop-len" and "false") if the
      inherited property is found.

[1] PCI Bus Bindings to IEEE 1275-1994 Draft 1.5, 20 March 1995
[2] Item #303: PCI Bus Binding: Create reserved word in the PCI node

[ P1275 Item #314 -- Received: Wed Jan 31 17:27:30 PST 1996 ]