[rant] keeping policy in HAL

Peter Hutterer peter.hutterer at who-t.net
Tue Dec 2 02:10:39 PST 2008

On Tue, Dec 02, 2008 at 09:56:11AM +0000, Colin Guthrie wrote:
> Daniel Stone wrote:
> > Well, yes.  If you're using HAL, then you're using evdev.  If you're
> > using HAL to tell X that you're using another driver, then you're using
> > another driver.  Oh yeah, and HAL won't add the same UDI twice.
> So the correct solution here is to not use the "mouse" driver as per 
> Paulo's original snippet of xorg.conf but rather use evdev manually 
> configured in the xorg.conf with the
>   Option "Device" "/dev/input/by-id/blahblahblah"
> set appropriately?
> So assuming a netbook with built in touch pad and USB mouse, if  X is 
> started prior to HAL, it will find it's built-in devices no problem (as 
> they've been saved in xorg.conf) and start using them, and later, when 
> HAL starts, it will not re-add the touch pad but will add in the USB mouse?

There's two different bits:
- the hal code in the server stops HAL from adding the same UDI twice
- code in the driver stops the driver from adding the same device twice

The first bit is only needed on hal restart, the second bit is what stops the
driver from adding the same device if it is specified once as
/dev/input/by-id/foobar and once at /dev/input/event1

Note that the second bit is evdev 2.1 only, as evdev 2.0 grabs the device.


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