[CDG5] ATI frozen mouse bug, cross-post from MacOS9Lives

[Jd Lyons]

On that note, do you think we could patch the Mac OS ROM to support the NV18 GPU this way?

I have a iMac G4 with the NV18, just a Geforce 4MX with 8x AGP support. It should work with OS 9’s nVidia drivers(NV17), but because the device ID is unknown to OS 9 it doesn’t.

> On Oct 10, 2019, at 6:22 AM, Jd Lyons <lyons_dj at yahoo.com> wrote:
> 
> It’s interesting you were able to patch the device ID, normally OS 9 style drivers are not fooled by Device ID patching, such as:
> 
> dev agp/@0
> 00005960 encode-int “ device-id” property
> 
> As most OS 9 style drivers don’t read the device ID from name space, they read it directly from the PCI Registers.
> 
> OS X, however, seems to read all PCI devices from name space, but not the CPU PVR.
> 
> nVidia FCode ROM's after the FX series can append the last half byte of the device ID in the NVStrap, but I’m not sure how OS 9 deals with that, as I’ve never been able to figure out how to hack nVidia driver support for OS 9.
> 
>> On Oct 9, 2019, at 11:44 PM, Elliot Nunn <elliotnunn at fastmail.com> wrote:
>> 
>> I have fixed the frozen mouse bug!
>> 
>> It was, as darthnVader hinted earlier, caused by the ATI extensions. So I took a
>> deep dive into the ATI driver architecture. This is the typical "life cycle" of
>> an ATI card in a NewWorld Mac:
>> 
>> 1.  If the card firmware lacks an ndrv (e.g. the Radeon 9200 in the mini), the
>>   MacOS uses its generic "COFB" ndrv to get basic video.
>> 2.  Extensions are loaded from disk. The ATI ROM Xtender or iMic's hacked "ATI
>>   Via Driver" extension can replace the previously loaded ndrv. No graphical
>>   acceleration yet.
>> 3.  The complex array of ATI extensions steps in, asks the loaded ndrv about the
>>   card using some private Status calls, and loads some acceleration code if the
>>   card is recognised. Accelerated 2D requires "ATI Resource Manager" and "ATI
>>   Graphics Accelerator" at minimum.
>> 
>> This was darthnVader's solution to get graphics acceleration working:
>> 
>> 1.  Insert a Mac OS X ndrv into iMic "ATI Via Driver" (better called "ATI
>>   RockHopper2 Driver" after the change).
>> 2.  Replace all or most occurrences of the 5961 device ID in the other extensions
>>   with 5962. Both IDs refer to the Radeon 9200, but the extensions only knew about
>>   the 5961 ID. (Occurrences of 5960 were also replaced -- see below.)
>> 
>> DarthnVader effectively turned our minis into Mac OS 9 gaming rigs!
>> Unfortunately, one of the binary patches intermittently broke hardware cursor
>> support. It might be due to the way that the PowerPC compiler optimised
>> select/case blocks. Sometimes I also experienced a black screen when the ATI
>> extensions loaded, which I think was related.
>> 
>> This is my solution:
>> 
>> 1.  Insert the same Mac OS X ndrv (ATY,RockHopper2 v1.0.1f63, from Mac OS X
>>   10.3.6) into the Mac OS ROM as an ndrv parcel, to mimic a firmware driver.
>> 
>> 2.  Patch that ndrv to replace 5962 with 5961 whenever it reads from PCI
>>   Configuration Space.
>>   - To achieve this, I got sidetracked and wrote a single-file PowerPC assembler
>>     script (ppcasm.py) and PEF dump/rebuild script (cfmtool.py):
>>     https://github.com/elliotnunn/tbxi-patches/
>> 
>> 3.  Use the unmodified ATI extensions from January 2005.
>>   - The extensions that we host in "9200os9.sit", supposedly from the rare July
>>     2005 release, do not work.
>>   - I think that they were binary-patched to enable support for the DVI-I Radeon
>>     9200 card, ID 5960. Specifically, the accl 4 resource of the "ATI Graphics
>>     Accelerator" is an identical build to January 2005, including the build
>>     date, but has 2/2 occurrences of 5961 replaced with 5960. It would be good
>>     to find the originals.
>> 
>> So here is my first ROM release of the year. It was derived from the
>> "OS9General" Mac OS ROM (v9.6.1) using my portable Mac mini patching system:
>> https://github.com/elliotnunn/tbxi-patches/blob/7a5d179/macmini.py
>> 
>> My ATALoad patch has also been applied, to allow Mac OS 9 to boot from volumes
>> that were formatted for Mac OS X, without first wiping the disk with "Mac OS 9
>> Drivers". I think that this is especially useful on machines that were formerly
>> Mac OS X-only.
>> 
>> I recommend that this ROM be included in a new release of the Mac mini ISO. It
>> should be combined with the unmodified ATI extensions from January 2005.
>> 
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>