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

Blue Swirl blauwirbel at gmail.com
Fri Oct 22 19:56:20 CEST 2010

On Fri, Oct 22, 2010 at 4:50 PM, Artyom Tarasenko <atar4qemu at gmail.com> wrote:
> On Fri, Oct 22, 2010 at 6:38 PM, Tarl Neustädter <tarl-b2 at tarl.net> wrote:
>> 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.
> Actually I meant "in qemu", but asked on a wrong mailing list, sorry
> for the noise.
> (Most of the developers are present in both lists anyway).

In QEMU, EBus provides an isa_mmio region, so all ISA devices with PIO
show up as MMIO in the EBUS PCI region 0 . For example, the first
16550 serial port has a hard-coded PIO base of 0x3f8, so it can be
accessed at 0x1fe020003f8.

Though actually also APB/PBM happens to route PCI PIO to this region,
so maybe EBus has no effect ;-)

>>>> 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.
> Thanks for the hint! This can save us some time & troubles.
> Just out of curiosity - do you have an example for the additional stuff`?

These devices are not in U5: 'SUNW,lom', 'adc', 'beeper',
'display7seg', 'gpio', 'i2c'.

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