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

[Artyom Tarasenko]

On Mon, Jan 19, 2015 at 4:01 PM, Andreas Färber <address@hidden> wrote:
> Am 19.01.2015 um 13:57 schrieb Artyom Tarasenko:
>> On Mon, Jan 19, 2015 at 1:45 PM, Paolo Bonzini <address@hidden> wrote:
>>> On 19/01/2015 12:35, Mark Cave-Ayland wrote:
>>>> Similar to m48t59_init(), add a mem_base value so that NVRAM can be mapped 
>>>> via
>>>> MMIO rather than ioport if required.
>>>>
>>>> Signed-off-by: Mark Cave-Ayland <address@hidden>
>>>> ---
>>>
>>> Is it really ISA if it's MMIO?  In other words, why can't this be a
>>> sysbus device?
>>
>> 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.

> 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?

Artyom

> IndustryPack is an example of a custom bus
> that sits behind a PCI bridge and doesn't need a global variable.
>
> Also, wasn't Hervé's(?) plan to get rid of mem_base completely by always
> passing a pointer to ISADevice/ISABus around? It should only be needed
> when somewhere NULL is being passed, no?
>
> Regards,
> Andreas
>
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-- 
Regards,
Artyom Tarasenko

SPARC and PPC PReP under qemu blog: http://tyom.blogspot.com/search/label/qemu