[PATCH v1] wayland-api: added name/seatname properties to the wl_output

Zhang, Xiong Y xiong.y.zhang at intel.com
Wed Nov 5 21:36:32 PST 2014

> On Fri, 17 Oct 2014 12:37:37 +0300
> Imran Zaman <imran.zaman at gmail.com> wrote:
> > In a multi-seat configuration, clients may need to filter out the
> > outputs based on the (udev) seat it is hooked to or based on the name
> > of the output.
> > Since version of the output is increased, the change does not affect
> > the current implementation and is optional whoever wants to use the
> > properties of the output (e.g. its very similar that input which has
> > the name property attached to it).
> >
> > Signed-off-by: Imran Zaman <imran.zaman at gmail.com>
> I explained this to you in IRC, and I will document it here again.
> The seatname event is the wrong approach to solving the issue, and will not be
> accepted. The other event, output name, might be useful though, but we need
> to look at it separately and see what use cases it serves.
> First, we need to define some concepts.
> A physical seat is a set of physical input and output devices. Each physical seat
> would have a different person working on it. Every person has his own monitors,
> keyboards, mice, etc. Most often, these seats are completely isolated, in that
> one person cannot touch another person's desktop or apps. People like privacy.
> Multi-seat means multiple physical seats, which are all served by the same
> machine. Implementing the isolation is the major issue here, and also what I
> understand is the primary problem you are trying to solve.
> Wayland's wl_seat is not a physical seat. It is not a seat at all.
> wl_seat is just a collection of input devices (no output devices!).
> Several mice under the same wl_seat act as a single pointer. Several keyboards
> under the same wl_seat act as a single keyboard.
> A physical seat may contain multiple outputs (monitors) and multiple wl_seats.
> All these wl_seats will share the same desktop and user. That desktop expands
> to all the outputs of the physical seat. Multiple wl_seats on the same server is
> not multi-seat, it is more like multi-pointer and multi-keyboard. You get one
> pointer per wl_seat, and one keyboard focus per wl_seat. Each wl_seat may be
> typing to a different window at the same time, within the same desktop.
You are absolutely right. But I think wl_seat is equal to physical seat in some conditions and we could use wl_seat as physical seat in our problem. 
Which component will define physical seat ?
We could bind input devices to wl_seat through udev rules and bind outputs to wl_seat through weston.ini, so we could think wl_seat is equal to physical seat if we set all the config file correctly.
This way we could use wl_seat to do resource isolation.

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