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

[Andreas Färber]

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? I
previously discussed with Mark that it should be an EBusDevice, not an
ISADevice or SysBusDevice. 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

-- 
SUSE Linux GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Felix Imendörffer, Jane Smithard, Jennifer Guild, Dilip Upmanyu,
Graham Norton; HRB 21284 (AG Nürnberg)