Heads up: X server configuration changes

[Peter Hutterer]

On Tue, Feb 16, 2010 at 12:16:42PM +0100, Michal Hlavinka wrote:
> > > > So you're running an X server? Well, my lad or lass, sit down and let
> > > > me tell you about the neverending story of X server input
> > > > configuration changes that has hopefully ended now.
> > > > I'm just pushing the latest X server goodness into rawhide and enabling
> > > > udev, completing (from the X server's POV) the excision of the hardware
> > > > abstraction layer that shall not be named.
> > > > 
> > > > >From F9 to including F12 (and rawhide until today) we've used hal to
> > > > 
> > > > discover the input devices. For lack of better options, this means that
> > > > many configurations have moved into fdi files. As you may know, hal is
> > > > deprecated and as much as fdi files may be pleasing to the eyes,
> > > > there's just no future in them. You'll just have to let it go, even if
> > > > it hurts.
> > > > 
> > > > Instead, we have the newest latest and greatest bits, namely
> > > > xorg.conf.d support and InputClasses. You can drop configuration files
> > > > into the new directory and the server will pick it up on startup.
> > > > e.g. /etc/xorg.conf.d/foobar.conf
> > > > "A configuration directory? Is this even possible?" you say? I know, it
> > > > sounds mightily advanced but we have to keep surfing the wave of new
> > > > technological achievements.
> > > > 
> > > > The existing section types in xorg.conf(5) weren't really suitable, so
> > > > we now have something that resembles the functionality provided by
> > > > hal's fdi files. A section of type InputClass will match against
> > > > multiple devices and even hotplugged ones - depending on the match
> > > > rules. An example section looks like this:
> > > > 
> > > > Section "InputClass"
> > > > 
> > > >         Identifier "superhero mouse config"
> > > >         MatchIsPointer "on"
> > > >         MatchProduct "Mighty Mouse"
> > > >         Driver "evdev"
> > > >         Option "X-Ray vision" "on"
> > > > 
> > > > EndSection
> > > > 
> > > > Any pointer device that contains "Mighty Mouse" in its product name
> > > > will match against this section and be added with the evdev driver and
> > > > the options as specified. That's just one example, I've tried to
> > > > detail the new configurations on our wiki.
> > > > https://fedoraproject.org/wiki/Input_device_configuration
> > > > If you think there's anything missing, please let me know or add it
> > > > yourself.
> > > 
> > > How is this going to affect some users that don't read release notes nor
> > > fedora devel list? Also, I have some configuration in fdi files (for
> > > touchpad for example). Will it still work with some (not too much
> > > visible?) complains in logs "this is deprecated"? Will it stop working
> > > without any information in logs? ...
> > 
> > hmm, at this point, yes, pretty much.
> > The fdi files are merged in by HAL itself and their content is part of the
> > information that HAL provides to the server. since the server doesn't
> > listen to HAL anymore, this information gets ignored.
> > All you'll see in the log is that it now says "udev" where it used to say
> > "HAL".
> > 
> > I can put a giant warning into the log that if input devices don't work
> > then the users should have a look at the website above for
> > reconfiguration. How does that sound? Do you have any better suggestions?
> 
> Are existing *.fdi files going to be used by something (except hal itself)? If 
> not, hal should be complaining during start up about "deprecated configuration 
> found".

input.x11_driver and input.x11_options are used only by X, so that'd be an
option.

> Also, is this 1:1 change or was something "improved", so we can see changes in 
> behavior for touchpad or anything else?

The problem we had over the last few releases is that we had to resort to
sticking xorg configuration into HAL for lack of an xorg-specific way. this
was bad to begin with but got worse when HAL was deprecated. now we have to
switch to a new config backend (udev) and instead of porting xorg
configuration in HAL format to xorg configuration in udev format, we
implemented an actual xorg-specific way upstream. so now, your xorg-specific
configuration can be in xorg.conf or in /etc/xorg.conf.d/.

so in that way - it's mostly a 1:1 change in functionality, but an
improvement in terms of integration.

neither server nor driver behaviour is affected by this, though, it's simply
a change in how to get the same configuration options into the server.
 
Cheers,
  Peter