[PATCH] Add configuration option for use of SIGIO handlers for input events

[Peter Hutterer]

On Wed, Oct 07, 2009 at 12:25:49AM +0100, Nix wrote:
> > When you have AEI off, the server will require a CorePointer and
> > CoreKeyboard device in the config (and create default devices if not found).
> > The same devices will then be added thanks to HAL, resulting in duplicate
> > button presses and triple key presses*.
> 
> ... which are not observed here. That I've configured the X server with
> --disable-config-hal is possibly relevant.

disable-config-hal should set AutoAddDevices, AutoEnableDevices and
AllowEmptyInput to false by default. 
 
> I suspect that with AllowEmptyInput on, the server is attempting to get
> devices from HAL alone even when it hasn't been compiled with HAL
> support, and ends up getting devices from nowhere.

On its own though AEI only controls if a core pointer + keyboard have to be
present at startup. If you turn it on, it'll ignore the lack of devices, if
you turn it off, it'll force the devices.

> See, that's not what I'm objecting to. It's the way that the upgrade to
> x11-xserver 1.5 left me with a non-working keyboard because of this
> mess, and then so did the upgrade to 1.6, because the meaning of
> existing configuration keys had *changed*! X used to be really, really
> good at backward compatibility... 

the input system has changed a lot since 1.3. It was essentially rewritten,
multiple times. Now those rewrites are done and we're stable again.
Sometimes things have to get worse before they get better.

> Still it would be nice if some of these whizzy new features got documented
> somewhere X-related rather than just landing in random blog posts and
> mailing list threads scattered around the web. I can understand your not
> doing it, you've been trying to document Xkb and that would drive anyone
> to despair ;P but it's annoying that nobody is doing it that I can see.)

If every user that complained about HAL and how problematic it is
to set up had spent the time documenting it instead of complaining on
mailing lists, forums and others we'd have some pretty decent documentation
by now. Unfortunately, after you explain something, people tend to disappear
instead of spending the extra time writing it up and documenting it for
others. We have a wiki, so there's no reason why there can't be a
centralised documentation.

It's hard for me to judge what isn't already commonly known since, well, I
know it. Writing documentation is hard because of that, and it's even harder
if you have people from all sides shouting at you about various bugs.

Cheers,
  Peter