[PATCH] DRI2: Expose API to set drawable swap limit.

[Mario Kleiner]

On Oct 28, 2010, at 6:10 PM, Pauli Nieminen wrote:

>> I think we should have some way for the drivers to back out of this
>> gracefully or at least cover their tails. E.g., allow the ddx to set
>> a hard upper limit for the swap_limit, in a new field max_swap_limit.
>> Your patch could make sure that swap_limit is never set to a value
>> higher than that. Then the intel and radeon ddx could set
>> max_swap_limit = 1 unless users somehow (xorg.conf option? dri.conf?)
>> opt into risky higher max_swap_limits.
>
> True.
>
> I intended DRI2SwapLimit to be called from DDX only. DDX only entry  
> wouldn't
> need any checks for limit changes.
>
> If we assume that all calls to DRI2SwapLimit are anyway driver  
> initiated then
> max_swap_limits would only guard driver against it self.
>
> I can add the max_swap_limit if there is real need for it.
>
>>
>> Or some part of the implementation (your patch? the ddx itself?)
>> should output some warning in the x log if a value is selected that
>> it can't reliably handle, so app developers aren't confused to death
>> about weird behaviour.
>>
>
> DDX would have to implement the option and warning.
>

Ok, sounds good. As long as the ddx has control over the settable  
swap_limit, i'm perfectly fine with it.

>>
>> Good point. I wasn't aware of that. So something like sketched above
>> should/could be implemented inside the ddx instead of the common
>> server code. But there, where it can already exchange to the new
>> front, it should work, right?
>>
>
> yes. It would work.
>

Good. So that's one way to do it in the ddx.

Thanks,
-mario