[PATCH] xserver: add udev/systemd multi-seat support

Peter Hutterer peter.hutterer at who-t.net
Mon Sep 5 15:09:07 PDT 2011

On Sun, Sep 04, 2011 at 10:44:21AM +0200, Colin Guthrie wrote:
> 'Twas brillig, and Lennart Poettering at 17/07/11 02:33 did gyre and gimble:
> > Add support for multi-seat-aware input device hotplugging. This
> > implements the multi-seat scheme explained here:
> > 
> > http://www.freedesktop.org/wiki/Software/systemd/multiseat
> > 
> > This introduces a new X server switch "-seat" which allows configuration
> > of the seat to enumerate hotplugging devices on. If specified the value
> > of this parameter will also be exported as root window property Xorg_Seat.
> > 
> > To properly support input hotplugging devices need to be tagged in udev
> > according to the seat they are on. Untagged devices are assumed to be on
> > the default seat "seat0". If no "-seat" parameter is passed only devices
> > on "seat0" are used. This means that the new scheme is perfectly
> > compatible with existing setups which have no tagged input devices.
> > 
> > This also optimizes the udev code in away that is beneficial for systems
> > that do not support new udev/systemd style multi-seat: the patch makes
> > use of libudev functions to limit enumerating/monitoring of devices to
> > actual input devices. This should speed up start-up and minimize
> > wake-ups, since we will only enumerate/monitor the devices we are
> > interested in instead of all devices on the machine and all events they
> > generate.
> > 
> > Finally, this also unifies the code paths for the udev "change" and
> > "add" events, since these should be handled the same way in order to be
> > robust to "udevadm trigger" calls, or lost netlink messages. This also
> > simplifies the code.
> > 
> > Note that the -seat switch takes a completely generic identifier, and
> > that it has no effect on non-Linux systems. In fact, on other OSes a
> > completely different identifier scheme for seats could be used but still
> > be exposed with the Xorg_Seat and -seat.
> > 
> > I tried to follow the coding style of the surrounding code blocks if
> > there was any one could follow.
> I didn't see any feedback on this patch. Did anything more happen
> regarding it?
> Does it need a bug opened?

it's in my -next branch which will be merged as soon as I get reviewed-by
for the smooth scrolling patches here:

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