Add serial to wl_output::geometry?

Philipp Kerling pkerling at
Fri Aug 18 07:53:48 UTC 2017


Am Freitag, den 18.08.2017, 10:47 +0300 schrieb Pekka Paalanen:
> On Thu, 03 Aug 2017 08:27:06 -0400
> Simon Ser <contact at> wrote:
> > Hello,
> > I'm writing a Wayland client that needs to keep track of screens
> > across reboots. I registered a wl_output::geometry event handler.
> > This event already has the fields "make" and "model", but is
> > missing
> > "serial". Is there a way to get an output serial (something like
> > "HS3P505873")? Would it be possible to add it to the protocol or is
> > it too late? Is there another way to identify screens?
> Hi Simon,
> these are very good questions. I have a vague recollection this has
> been discussed before on wayland-devel@, but personally I may have
> been
> skeptical about the use cases at the time.
For reference: 
A lot of points were discussed back then already.

> Anyway, nowadays I think adding the physical monitor serial to
> wl_output as a new event should be fine. There are some details to
> discuss like if the monitor hardware does not provide a reliable
> serial, should the compositor maybe manufacture some GUID or just
> leave
> the serial unset. What about "monitors" that are not physical
> devices,
> like a window in another window system - should one relay the serial
> from the other window system's monitor, manufacture an artificial
> based on e.g. window system connection, or just not send a serial at
> all.
You could argue that similar concerns apply to "make" and "model", but
they only have a very vague description in the protocol.

> Maybe it would be best to just say the serial is from a locally
> connected monitor hardware (or equivalent), and leave the cases where
> the hardware serial is not available or the output is not a local
> physical monitor to not send a serial.
Also needs to be discussed whether the values should be compatible
accross compositors (e.g. make and model are not currently because of
their vague definition).


More information about the wayland-devel mailing list