Re: [Xen-devel] Xen 3.4.x and request-abs-pointer

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

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.
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.


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