Re: [PATCH] pci-assign: Hide ioport regions on lacking sysfs support

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-05-30 10:21, Avi Kivity wrote:
> On 05/29/2012 08:28 PM, Alex Williamson wrote:
>> On Tue, 2012-05-29 at 20:13 +0300, Avi Kivity wrote:
>>> On 05/29/2012 08:04 PM, Jan Kiszka wrote:
>>>> As suggested by Alex: Instead of failing if the kernel does not allow us
>>>> to speak to an ioport region, warn the user but, hide the region and
>>>> continue.
>>>
>>>
>>> Should we not, in addition, abort if the region is actually used?  A
>>> guest malfunction is likely if we don't.
>>
>> The only way we could know that it's used is if it's the device ends up
>> with no valid regions as a result of this.  Otherwise it's dependent on
>> both the device and the driver whether it can still function without the
>> i/o port regions.  Thanks,
> 
> If the I/O callback is called, we know it's used.

We neither expose the region to the guest (so the guest has no clue
where to write to unless it assumes a fixed address - of which we have
no clue) nor register any callback for it.

Jan

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