[Xorg] Input device hotplug

Jon Smirl jonsmirl at yahoo.com
Wed Jun 23 10:47:28 PDT 2004

On Linux 2.6 you can put an executable in /etc/hotplug.d/input and it
will be run whenever a new device is add/removed. The program/script
could check if xserver is running and tell it about the new device.

This doesn't work for PS/2 devices right now but that is a known
problem and on the queue to be fixed.

--- Kristian_Høgsberg <krh at bitplanet.net> wrote:
> Hi all,
> I've been working on making the X.org server hotplug aware with
> respect
> to input devices.  The current situation is that all devices must be 
> setup in the config file and adding new devices requires config file 
> editing and server restart.  What I've been trying to implement is
> that 
> you can plug in an input device while the X server is running and it 
> will show up as a new XInput device.
> The overall design I'm thinking of is to keep the device discovery 
> mechanism out of the X server.  By adding requests to add and remove
> devices a client program can monitor hotplug events and tell the
> server 
> to add or remove devices accordingly.
> I have a prototype running were I've added AddInputDevice() and
> RemoveInputDevice() in the XFree86-Misc extension:
>    typedef struct {
>        char*	name;
>        char*	value;
>    } XF86MiscDriverOption;
>    Status XF86MiscAddInputDevice(Display *dpy,
>                                  const char *identifier,
>                                  const char *driver,
>                                  XF86MiscDriverOption *options,
>                                  int option_count);
>    Status XF86MiscRemoveInputDevice(Display *dpy,
>                                     const char *identifier);
> i.e. the AddInputDevice arguments correspond to the InputDevice
> section 
> of the config file.  The implementation mimicks the server 
> initialization sequence; it loads the driver, builds an option list
> from 
> the given options, calls PreInit(), and adds the device.
> In the prototype I'm using HAL (hal.freedesktop.org) on Linux to 
> enumerate and discover devices.  Other systems could use other 
> mechanisms, but HAL is intended to be cross platform, and a FreeBSD
> port 
> is being discussed right now on the list.
> One thing I'ld like to discuss is where to add the add and remove
> device 
> interface -- I dont think XFree86-Misc is the right place.  My first 
> approach to this was that the new functionality should be an Xorg 
> private interface, but I'm thinking that maybe it would be better if
> it 
> was a standardized extension to XInput.  In that case, is the
> proposed 
> interface too Xorg specific?
> Comments are welcome.  I'm currently trying to get my prototype
> cleaned 
> up, and then I'll attach it to a bugzilla entry
> Kristian
> _______________________________________________
> xorg mailing list
> xorg at freedesktop.org
> http://freedesktop.org/mailman/listinfo/xorg

Jon Smirl
jonsmirl at yahoo.com

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