[RFC wayland-protocols] inputfd - direct input access protocol

Simon McVittie smcv at collabora.com
Thu Apr 6 10:49:26 UTC 2017

On Wed, 05 Apr 2017 at 17:45:51 -0700, Roderick Colenbrander wrote:
> I wonder how Valve is doing this on Steam as with the Steam
> Controller, which I haven't used. I think they are allowing it to
> replace keyboard and mouse kind of. Curious how they are solving this.
> My guess is they are actually spoofing a mouse for game compatibility.

It pretends to be a mouse, a keyboard and an XBox 360 gamepad all at
the same time, possibly with the help of uinput (I'm somewhat hazy on
the details, having done my best to forget it all once I got it working).
The events that it produces are configurable per-game, so for instance the
right touchpad might be generating right analogue stick movements, mouse
motion, or even keypresses, but I don't know whether that's done by remapping
events in user-space or by asking the device firmware to send different
packets over USB.

Steam also has in-home streaming, which relays input events across
the network from the viewer/controller machine (a PC or Steam Link)
and AIUI uses uinput to emulate all the right devices on the machine
that is actually running the game.

[Disclaimer: I worked on some SteamOS code a while ago, but it was
packaging/package management and not input or graphics, so this is
entirely an ordinary user view from the outside. For non-speculation
you'd have to ask Valve.]


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