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dingusppc/zdocs/get-inherited-property notes.txt

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Add known Open Firmware 1.0.5 bugs Additional notes about get-inherited-property and map-in.
2022-08-22 07:45:28 +00:00
get-inherited-property and map-in notes
by joevt
==========================================================================================
PowerMac 8600
rom notes:
The Open Firmware part (192k) of the 4MB ROM in the 8600 is the same in the 9500 and is probably the same for these other Macs:
" AAPL,7500"
" AAPL,8500"
" AAPL,9500"
" AAPL,7300"
Detokenized FCode from Mac ROM:
external-token get-inherited-property \ [0x0ca] 0x21d
b(:) \ [0x0b7]
2 mac_rom_401 \ mac_rom_code_45C \ [0x401] \ I don't know how token 401 turns into token 45C or the how the other tokens change.
?my-self \ [0x654]
8 mac_rom_table_2 \ mac_rom_code_45E \ [0x41a] \ The fcode compiler is probably responsible for these changes.
b(<mark) \ [0x0b1]
8 mac_rom_table_1 \ mac_rom_code_45D \ [0x412]
b?branch \ [0x014] 0x30
8 mac_rom_table_1 \ mac_rom_code_45D \ [0x412]
mac_rom_field_512_4 \ [0x512]
@ \ [0x06d]
0xC mac_rom_table_2 \ mac_rom_code_45E \ [0x41b]
0 mac_rom_table_1 \ mac_rom_code_45D \ [0x410]
4 mac_rom_table_1 \ mac_rom_code_45D \ [0x411]
0xC mac_rom_table_1 \ mac_rom_code_45D \ [0x413]
unnamed_fcode_79e \ [0x79e]
?dup \ [0x050]
b?branch \ [0x014] 0x14
dup \ [0x047]
unnamed_fcode_796 \ [0x796]
@ \ [0x06d]
swap \ [0x049]
unnamed_fcode_797 \ [0x797]
@ \ [0x06d]
\\ missing dup here!!!!
-1 \ [0x0a4]
= \ [0x03c]
b?branch \ [0x014] 0x4
drop \ [0x046]
execute \ [0x01d]
b(>resolve) \ [0x0b2]
false \ [0x557]
exit \ [0x033]
b(>resolve) \ mac_rom_code_45D \ [0x0b2]
8 mac_rom_table_1 \ [0x412]
mac_rom_field_513_8 \ [0x513]
@ \ mac_rom_code_45E \ [0x06d]
8 mac_rom_table_2 \ [0x41a]
bbranch \ [0x013] 0xffffffcf
b(>resolve) \ [0x0b2]
true \ [0x558]
b(;) \ [0x0c2]
Detokenized FCode converted to Forth:
: get-inherited-property \ (21d) [0ca 0b7]
2 mac_rom_401 \ [401]
?my-self ( -- ihandle ) \ return iHandle of current instance \ [654]
8 mac_rom_table_2 \ [41a]
begin \ [0b1]
8 mac_rom_table_1 \ [412]
while \ (0x30) [014]
8 mac_rom_table_1 \ [412]
mac_rom_field_512_4 \ [512]
@ \ [06d]
0xC mac_rom_table_2 \ [41b]
0 mac_rom_table_1 \ [410]
4 mac_rom_table_1 \ [411]
0xC mac_rom_table_1 \ [413]
colon_definition_function_79e \ (79e) [79e]
?dup \ [050]
if \ (0x14) [014]
dup \ [047]
field_796 \ (796) [796]
@ \ [06d]
swap \ [049]
field_797 \ (797) [797]
@ \ [06d]
\\ missing dup here!!!!
-1 \ [0a4]
= \ [03c]
if \ (0x4) [014]
drop \ [046]
execute \ [01d]
then \ [0b2]
false \ [557]
exit \ [033]
then \ [0b2]
8 mac_rom_table_1 \ [412]
mac_rom_field_513_8 \ [513]
@ \ [06d]
8 mac_rom_table_2 \ [41a]
repeat \ (0xffffffcf) [013 0b2]
true \ [558]
; \ [0c2]
Disassembled PPC compiled FCode taken from Open Firmware RAM:
Offset Hex Dest Offset Instruction Operands Comments
0143C0: ........ \ fcode link (offset) to previous word or 00000000 for first word
0143C4: 80 \ fcode flags 80 = fdefd (fcode is defined)
0143C5: b(:) \ [0x0b7] 0x21d get-inherited-property
0143E0: 967E FFFC stwu r19,-4(r30) \ execution token is here - always a multiple of 8
0143E4: 7E68 02A6 mflr r19 \ every compiled b(:) word starts with these two lines 967EFFFC, 7E6802A6
0143E8: 3860 0002 li r3,2
0143EC: 4BFE DA1D 001E08 bl mac_rom_code_45C
0143F0: 4BFF 5EA9 00A298 bl ?my-self
0143F4: 3860 0008 li r3,8
0143F8: 4BFE DA69 001E60 bl mac_rom_code_45E
0143FC: 3860 FFFF li r3,-1
014400: 3860 0008 li r3,8
014404: 4BFE DA45 001E48 bl mac_rom_code_45D
014408: 4BFE D871 001C78 bl mac_rom_code_455
01440C: 4800 0098 0144A4 b $+152
014410: 3860 0008 li r3,8
014414: 4BFE DA35 001E48 bl mac_rom_code_45D
014418: 4BFF 0551 004968 bl mac_rom_field_512_4
01441C: 4BFE E52D 002948 bl @
014420: 3860 000C li r3,0x000C
014424: 4BFE DA3D 001E60 bl mac_rom_code_45E
014428: 3860 0000 li r3,0
01442C: 4BFE DA1D 001E48 bl mac_rom_code_45D
014430: 3860 0004 li r3,4
014434: 4BFE DA15 001E48 bl mac_rom_code_45D
014438: 3860 000C li r3,0x000C
01443C: 4BFE DA0D 001E48 bl mac_rom_code_45D
014440: 4BFF F321 013760 bl mac_rom_colon_79E
014444: 4BFE E965 002DA8 bl ?dup
014448: 4BFE D831 001C78 bl mac_rom_code_455
01444C: 4800 003C 014488 b $+60
014450: 4BFE E921 002D70 bl dup
014454: 4BFF F1FD 013650 bl mac_rom_field_796
014458: 4BFE E4F1 002948 bl @
01445C: 4BFE EA95 002EF0 bl swap
014460: 4BFF F209 013668 bl mac_rom_field_797
014464: 4BFE E4E5 002948 bl @
014468: 4BFE EBD9 003040 bl -1
01446C: 4BFE F425 003890 bl =
014470: 4BFE D809 001C78 bl mac_rom_code_455
014474: 4800 000C 014480 b $+12
014478: 4BFE E999 002E10 bl drop
01447C: 4BFE CBE5 001060 bl execute
014480: 4BFF 2681 006B00 bl false
014484: 4BFE CC15 001098 bl exit
014488: 3860 0008 li r3,8
01448C: 4BFE D9BD 001E48 bl mac_rom_code_45D
014490: 4BFF 04E9 004978 bl mac_rom_field_513_8
014494: 4BFE E4B5 002948 bl @
014498: 3860 0008 li r3,8
01449C: 4BFE D9C5 001E60 bl mac_rom_code_45E
0144A0: 4BFF FF60 014400 b $-160
0144A4: 4BFF 267D 006B20 bl true
0144A8: 4BFE CBF0 001098 b exit \ every compiled b(:) word starts ends with a branch to exit
0144AC: 0000 0000 \ filler makes fcode length a multiple of 8
========================================
The following Forth script changes the 0x22nd instruction (offset 0x88) in get-inherited-property from the Forth word "-1" to "dup -1".
: myGIPpatch dup -1 ;
' get-inherited-property 22 na+ ' myGIPpatch BLpatch
The following tests the patch:
" crap" get-inherited-property \ should return true
" name" get-inherited-property \ should return nameaddr, namelen, false
The following undoes the patch:
' get-inherited-property 22 na+ ' -1 BLpatch
I don't know what kind of properties would return a length of -1 which would cause the drop and execute words to run but there would be no address to execute (stack underflow) without the dup word in the patch.
A method needs to be used to decide if the patch is needed:
- test for add-range (see below)
- test get-inherited-property and check if stack depth is 2 instead of 3
The patch offset (0x88) will have to be verified for every Mac that has the bug.
=========
The Radeon 7000 defines an unnamed value that can have one of following values:
0: for machines that do not have the "AAPL,cpu-id" property (newer Macs like the iMac)
1: for machines that have the "AAPL,cpu-id" property but do not have the get-inherited-property bug
3: for machines that have the "AAPL,cpu-id" property and the get-inherited-property bug (older Macs like the 8600)
However, when using the value, the Radeon 7000 only distinguishes between 0 and not 0 (doesn't have "AAPL,cpu-id" and has "AAPL,cpu-id"). If the value is not zero, the Radeon 7000 uses "assigned-addresses" in the calculation of the address for the map-in method.
The method that the Radeon 7000 uses (the "AAPL,cpu-id" check) to decide whether or not assigned-addresses needs to be used is different than the method described by the "PCI Bus Binding to Open Firmware Revision 2.1" documentation. I don't know why ATI didn't do it that way.
==========================================================================================
PowerMac G3 233 (beige) Open Firmware 2.0f1:
- The PCI bridge in the G3 does not implement the add-range method which signifies that get-inherited-property returns the correct number of parameters
- get-inherited-property is implemented the same as Open Firmware 2.4 (see below)
==========================================================================================
PowerMac G3 300 (beige) Open Firmware 2.4:
- this version of Open Firmware is the best Old World Mac Open Firmware to work with since it has names for almost everything.
Detokenized FCode converted to Forth:
: get-inherited-property \ (21d) [0ca 0b7]
{ local_0 local_1 ; local_2 local_3 } \ [409]
?my-self \ [652]
-> local_2 \ [41a]
begin \ [0b1]
local_2 \ [412]
while \ (0x31) [014]
local_2 \ [412]
>in.device-node \ [526]
@ \ [06d]
-> local_3 \ [41b]
local_0 \ [410]
local_1 \ [411]
local_3 \ [413]
find-property \ [790]
?dup \ [050]
if \ (0x15) [014]
dup \ [047]
>prop.addr \ [788]
@ \ [06d]
swap \ [049]
>prop.len \ [789]
@ \ [06d]
dup \ [047]
-1 \ [0a4]
= \ [03c]
if \ (0x4) [014]
drop \ [046]
execute \ [01d]
then \ [0b2]
false \ [56b]
exit \ [033]
then \ [0b2]
local_2 \ [412]
>in.my-parent \ [527]
@ \ [06d]
-> local_2 \ [41a]
repeat \ (0xffce) [013 0b2]
true \ [56c]
; \ [0c2]
==========================================================================================
from "Writing FCode Programs For PCI"
\ Some of Apple’s Open Firmware implementations have a bug in their map-in method. The
\ bug causes phys.lo and phys.mid to be treated as absolute addresses rather than
\ offsets even when working with relocatable addresses.
\ To overcome this bug, the Open Firmware Working Group in conjunction with Apple has
\ adopted a workaround that is keyed to the presence or absence of the add-range method
\ in the PCI node. If the add-range method is present in an Apple ROM, the map-in
\ method is broken. If the add-range property is absent, the map-in method behaves
\ correctly.
\ The following methods allow the FCode driver to accomodate both broken and working
\ map-in methods.
: map-in-broken? ( -- flag )
\ Look for the method that is present when the bug is present
" add-range" my-parent ihandle>phandle ( adr len phandle )
find-method dup if nip then ( flag ) \ Discard xt if present
;
==========================================================================================
from "PCI Bus Binding to Open Firmware Revision 2.1"
1. 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 that the phys.lo address to be extracted from the "assigned-addresses" prop-erty
and that the get-inherited-property method 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 (when n=0) and that get-inher-ited-
property returns three stack items (prop-addr prop-len and false) if the inherited
property is found.
==========================================================================================
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