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

[Programmingkid]

On Feb 11, 2016, at 3:24 AM, Mark Cave-Ayland wrote:

> 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 ;)

Definitely. I'm hoping we can fix this problem and hope it helps Mac OS 9 as well.