Re: [PATCH v2 2/3] grackle: use qdev gpios for PCI IRQs

[Mark Cave-Ayland]

On 16/10/2020 01:26, BALATON Zoltan via wrote:

> As said in previous message the i2c and SPD patches are not quite ready yet so I've 
> omitted those from this series, I may rework them later once this part is merged and 
> can rebase the rest on top of that. We would also need your screamer patches to get 
> the Mac ROM working, what is still missing for those?

The 2 main reasons for not merging the screamer patches so far are:

1) Hangs in MacOS 9.0 and 9.1 on startup

Probably related to DBDMA interrupts, but I haven't had time to dig into this in much 
detail.

2) Reduced OS X emulation speed

When OS X detects the sound hardware it enables its internal sound engine which does 
2 things: firstly it constantly runs DBDMA requests which execute in the bottom-half 
even if no sound is being generated, so you end up reducing the raw emulation speed 
and secondly the OS X sound engine is floating point based so you end up running a 
lot more background floating point arithmetic in the OS.

I'm open to further ideas as to how this can be improved. The DBDMA overhead could be 
reduced by running DBDMA in the iothread if that is possible but that would be a fair 
bit of work.


ATB,

Mark.