Re: [Xen-devel] [PATCH v2 01/15] xen/arm: register mmio handler at runtime

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 04/08/2014 07:35 AM, Vijay Kilari wrote:
> On Fri, Apr 4, 2014 at 8:57 PM, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
>> On 04/04/2014 04:24 PM, Vijay Kilari wrote:
>>
>>>>> As I said on the previous version, it would be nice to remove check
>>>>> callback in the mmio_handler and replace it by addr/size. It's better if
>>>>> we might want to change the place in the memory following the guest.
>>>>>
>>>>> So the result function would be:
>>>>>
>>>>> register_mmio_handler(struct domain *d, read_t read, write_t write,
>>>>> addr, size);
>>>>>
>>>> OK.
>>>    Though you suggested, I kept this check handler because it gives 
>>> flexibility
>>> for driver to make additional checks if required apart from just checking 
>>> for
>>> address range.
>>
>> What kind of checks? If the handler is registered to a domain that means
>> we want to use it, right? It would seem strange to trap once a while.
> 
>    IMO, with check handler it will give more flexibility for driver to
> various kinds of checks.
> Ex: Driver wants to check for multiple addr ranges etc.,

From driver POV it's easier to have one range by set of callbacks rather
than multiple range.
Because you will end up to check in 2 place the address (once in check
and once in read/write callback).

You don't use this feature in your code and I don't think it will be
use, so I would prefer to get a rid of check and let handle_mmio do the
job for us.

Regards,

-- 
Julien Grall

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