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

[Jd Lyons]

Good work Elliot, looks like you had to dive pretty deep into the ATI Extensions for that.



> 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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