Re: [Qemu-devel] [PATCH 1/2] memory: Provide separate handling of unassigned io ports accesses

[Jan Kiszka <jan.kiszka@web.de>]

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On 2013-08-05 12:36, Peter Maydell wrote:
> On 5 August 2013 11:30, Jan Kiszka <jan.kiszka@web.de> wrote:
>> On 2013-08-05 11:59, Peter Maydell wrote:
>>> Or do you mean that if we had:
>>>
>>>  [ system memory region, with its own default read/write ops ]
>>
>> I cannot imagine how this could work. The system memory region has no
>> clue about what the regions below it can handle and what not. So it has
>> to pass through the io window.
> 
> The system memory region's just a container, you can add a
> background region to it at lowest-possible-priority, which
> then takes accesses which are either (a) not in any subregion
> or (b) in a subregion but that container doesn't specify
> its own io ops and nothing in that container handles the
> access. (Or you could create the system memory region with
> its own IO ops, which would have the same effect.)

First, we do not render MMIO and IO within the same address space so
far. But even if we would, the IO container now catches all accesses, so
the system memory region will never have its default handler run for
that window.

Jan



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