Re: Xen 3.4.x and request-abs-pointer

[John Haxby <john.haxby@oracle.com>]

On 05/07/10 17:41, Stefano Stabellini wrote:
> On Mon, 5 Jul 2010, John Haxby wrote:
>    
>> On 05/07/10 16:45, Stefano Stabellini wrote:
>>      
>>> That patch was recently reverted because it was the wrong fix:
>>>
>>>
>>>        
>> Rats.
>>
>> Back to my previous attempt then which seemed a little less elegant: the
>> idea was that I would initially register the pointer as relative but
>> check in the first call to xenfb_mouse_event() and if I had guessed
>> wrong, remove the existing mouse handler and add a new one with
>> registered as absolute.  If the mouse turns out to be absolute, we miss
>> the very first pointer event but this doesn't seem to be much of an
>> issue because everything will be sorted out on the next mouse event (the
>> various pieces of code that are interested in whether or not the mouse
>> is enabled seem to be OK about switching from relative to absolute).
>>
>> Before I commit a patch to electrons are the any obvious flaws in that
>> approach?
>>
>>      
>
> I think that solution is not very elegant besides it doesn't fix the
> basic issue that is on qemu side.
>    

Yeah, you're right.  It sucks.  That's what comes of writing down 
something random just before you go home for the day.

> The proper fix  would be to add a new hook in qemu like suggested
> in the previous email:
>
>    
>> In order to do that properly we need a new hook in qemu xen_backend: we
>> should probably rename the current connect hook to initialise and create
>> a new connect hook that would be implemented by xenfb to read
>> request-abs-pointer.
>>      
> Basically we need a new callback from xen_backend.c on
> XenbusStateConnected.
> The current "connect" hook can be called on both XenbusStateInitialised
> and XenbusStateConnected so it doesn't suit our needs.
> I suggest to rename the current "connect" hook to "initialised", and
> create a new "connect" hook that is called only on XenbusStateConnected.
> In the xenfb.c implementation of the new connect hook you can read
> request-abs-pointer and be sure that it was previously set by the guest.
>
>    

Sounds reasonable.

jch