[OpenBIOS] [PATCH] drivers/escc.c: Add slot-names property ch-a node under escc

[Mark Cave-Ayland]

On 09/02/16 15:28, Programmingkid wrote:

> On Feb 9, 2016, at 10:05 AM, Alyssa Milburn wrote:
> 
>> On Tue, Feb 09, 2016 at 09:47:57AM -0500, Programmingkid wrote:
>>>> You can assign addresses for serial DMA and even OS 9 will try poking at the
>>>> dbdma controller, so this is just a question of hooking up the qemu side. I
>>>> can try doing this later today if it's useful..
>>>
>>> It is definitely useful. The ability to run Mac OS 9 in QEMU depends on it.
>>
>> After a few days spent poking through the startup process in MacsBug, I'm
>> not sure this is true. But I'll hook it up later (if someone else doesn't do
>> it first).
> 
> You may be right. This code on Mac OS X does not allow the driver to work because of DMA issues. It is from the PPCSerialPort.cpp file. 
> 
>     // Calls the DMA function that knows how to
>     // handle all the different hardware:
>     SccSetDMARegisters(&Port, provider);
>     if ((Port.TxDBDMAChannel.dmaChannelAddress == NULL) ||
>         (Port.TxDBDMAChannel.dmaBase == NULL) ||
>         (Port.RxDBDMAChannel.dmaChannelAddress == NULL) ||
>         (Port.RxDBDMAChannel.dmaBase == NULL))
>         return false;

>From memory, we got away with just not having the DBDMA properties
present in the reg property when booting OS X for this reason: if they
are empty then they are simply ignored. Obviously OS 9 has slightly
different ideas here ;)


ATB,

Mark.