[OpenBIOS] sun4u ebus (was: Change ofmem_common.c)

Tarl Neustädter tarl-b2 at tarl.net
Fri Oct 22 18:38:10 CEST 2010

On 2010-10-22 5:28 AM, Artyom Tarasenko wrote:
> On Fri, Oct 15, 2010 at 7:57 PM, Blue Swirl<blauwirbel at gmail.com>  wrote:
>> Actually, while mc146818rtc is linked in, it's not used (there are
>> some machines that have similar device, so that's why it still hangs
>> around). m48t59 is on ebus.
> Btw, can you explain how the physical address of an ebus device can be
> calculated?
> Looks like they are relative to the ebus beginning and then to PCI,
> but what constants define the offsets?

In real Sun systems, offsets onto EBus are hard-coded into the circuitry. 
E.g., a 16550 chip will be at offset x003f8. Somewhere in the upper bits (I 
think where I have the "x") will be a select value which is decoded to provide 
a select pin for the particular chip.

In answer to your basic question, the EBus address values are provided to 
firmware by the hardware designers.
>> Is Netra-T1 OK?
> Wanted to check whether the current ebus mappings match Netra-T1 or
> U5, but haven't succeeded.
I would generally suggest steering clear of the Netra systems - they are Telco 
modifications of more basic systems. Going with a netra may cause you to deal 
with additional stuff you don't care about.

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