RandR 1.5 "Monitors" and splitting a single physical display

Jack Coulter jscinoz at jscinoz.so
Wed Mar 15 00:19:52 UTC 2017

Hi Nathan,

> I ran into issues trying to do setup multiple Monitors for an Output,
> and sent a mail to the list in September 2016; Aaron Plattner from
> NVIDIA responded, noting about the "ConnectionNumber" property from
> the xrandr --prop command.  The Intel hardware I'm using (Intel
> Skylake; Iris Pro Graphics P580 [8086:193d] (rev 09).
> The thread can be viewed here:
> https://lists.x.org/archives/xorg/2016-September/058245.html 
Thanks for the information, although after a brief read through the
linked thread, I'm not certain of the relevance of "ConnectorNumber" to
what we're trying to do.

> Jack, let me know if you figure this out, please and thank you! 
After some further reading of the RandR 1.5 spec, I noticed this tidbit
under RRSetMonitor:
> For each output in 'info.outputs, each one is removed from all
> pre-existing Monitors. If removing the output causes the list of
> outputs for that Monitor to become empty, then that Monitor will be
> deleted as if RRDeleteMonitor were called.
From reading this it seems that it is not possible to have multiple
monitor objects sharing the same output, making our use-case impossible
(outside of hacks such as fakexinerama).

To the wider list, I have to ask: Is this behaviour something that could
be amended in a future version of the specification? There are perfectly
valid use cases for multiple monitors on a single output (such as the
one detailed at the start of this thread).

Kind regards,

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