Re: [Qemu-ppc] [PATCH 2/2] m48t59: add mem_base value to m48t59_init_isa()

[Paolo Bonzini]

On 19/01/2015 16:22, Artyom Tarasenko wrote:
>>> >>
>>> >> On physical machines it's EBus, which is pretty much like 8-bit ISA.
>>> >> So, I think modelling it as ISA is closer to to the reality.
>>> >> But out of curiosity, would it be possible to have a sysbus device
>>> >> somewhere in a middle of PCI space? [...]
>> >
>> > Why would you want to use a SysBusDevice in the first place?
> Ask Paolo. :-) For me it's only important to have a MMIO device in the
> proper address range.

The reason I asked is simply because ISA devices never do MMIO (apart
for the VGA window).

>> > I previously discussed with Mark that it should be an EBusDevice, not an
>> > ISADevice or SysBusDevice.
> Interesting. I can't find this discussion in the list archive. Do you suggest 
> to
> create EBusDevices for all ISA devices (serial, parallel, keyboard,
> floppy) used in sun4u, or only for m48t59?
> What would be the advantage of using EBusDevice over ISADevice?

Is there a description of EBus and the sun4u memory map somewhere?

Is there an "EBus bridge" PCI device similar to the PCI-to-ISA bridge?

Paolo