XFree86 4.0 is the first official release of the new XFree86 4. XFree86 4 represents a significant redesign of the XFree86 X server. It is very important to keep in mind that XFree86 4 is still very much in development, and it contains a lot of new work. That means two things: there is a lot of new exciting stuff to try, but being new code, it hasn't had nearly as much of a workout as the stable 3.3.x releases. If you're looking for a well-tested, stable release, and can't afford the inconveniences that new software can sometimes cause, then you are probably better off sticking with the 3.3.x releases for now. If you have the resources to try out the new version and investigate its features, or if you just like being on the bleeding edge, then please try 4.0!
This release isn't quite as complete as we would have liked. The main missing pieces are a nice configuration tool and support for some of the hardware that 3.3.x supports. The first point means that configuring the server might be more painful than usual. The second means that your hardware might not be supported by 4.0, or it might be supported at a lesser level (conversely, some hardware is better supported in 4.0). We've attempted to provide some information about the second point in our Driver Status document. Please check there first before trying 4.0. Unfortunately that document is still fairly basic, but it should at least give you an idea of whether you're likely to be able to use 4.0 at all or not.
On the subject of configuration, we have updated the basic text-based
tool "xf86config" to generate config files in the format required
by 4.0 (3.3.x config files won't really work with 4.0). We're also
working on some other configuration tools, including one that is built-in
to the X server. An early version of this is included in the release,
and it works well for some hardware. To try it out, just run (as root)
"XFree86 -configure". Both of these configuration options will
at worst give you a reasonable starting point for a suitable configuration
file. We've put some effort into documenting the 4.0 config file format,
and you can find that information in the XF86Config manual page. Please
check that and the driver manual pages and related documentation for
further information about that.
Oh, another thing you might notice is that our documentation is rather patchy. Most of what is present should be in reasonable shape, but there are gaps. We thought it better to leave out docs that were very out of date rather than providing inaccurate and misleading information.
Finally, before you download and install the binary distributions for this release, please have a quick read through the Installation Document. It may save you some time.
If those cautionary notes haven't turned you away (and we certainly hope not), please read on... The sections below describe some of the new features and changes between 3.3.x and 4.0. There is a lot of new stuff, and we definitely don't have enough space to cover it all here.