X.Org developers are currently discussing the possibility to remove the KDrive, Xnest, and Xvfb technologies from the X.Org Server, citing that their functionality has been superseded by better alternatives and this could lead to trimming the xorg-server by over 30,000 lines of code.
On Monday there was a "pull to discuss" request by Jeremy Huddleston of Apple to remove KDrive (the former tiny X Server implementation), Xnest (allows for a nested X Server to run within an existing X.Org Server window), and Xvfb (running an X Server on a virtual frame-buffer) to be removed from the X.Org Server.
As said in Huddleston's mailing list message
([PULL to discuss] Remove kdrive, Xnest, and Xvfb
), "These need to die. This removes 30K lines of code from xorg-server. It must be good! Most functionality of these servers can be provide by Xorg with either the nested or dummy video driver. If someone really misses functionality, we should fix that deficiency in hw/xfree86, xf86-video-dummy, or xf86-video-nested. Also, there's nothing stopping anyone from using older server versions if they still need these DDXs. Ok, you may now commence with the flinging of FUD."
The X.Org developers responding to this pull request to kill KDrive, Xnest, and Xvfb have been largely in support of this code death sentence. There's been some concern raised that some functionality from Xvfb to allocate a frame-buffer in a memory mapped file or a shared memory segment can't yet be done within the fbdev DDX driver and there are a few options from Xnest that can't yet be handled by xf86-video-nested, but anyone so inclined could port the functionality to the DDX driver -- assuming anyone still uses this functionality.
There's also a potential blocker that in removing these features and relying upon their DDX driver alternatives, non-root users cannot use them since Xorg only reads configuration files from system directories when run as a root user.
It's not guaranteed right now that KDrive, Xnest, and Xvfb will be killed off in the very near future, but it looks likely at this point. If it's done within the next few months it will be a change for X.Org Server 1.13, which is expected for release in early September. Other X.Org Server 1.13 expected changes include better X Wayland support
, killing off XAA
, potential X.Org GPU hot-plugging
, a 250k+ line patch
, and potential bits of RandR 1.4