X Server

The X Server is the software that implements the X Windows protocol to the operating system.

The X Server used with NFB drivers is dynamic, meaning that drivers for specific graphics chips can be dynamically linked into the existing server at run time. See ``Writing NFB graphical adapter drivers'' for instructions about using the tools and the NFB interface to create display drivers that can be used with the SVR5, SCO OpenServer 5, and AIX 5L X servers.

On SVR5 and SCO OpenServer 5, the X Server functionality can also be extended dynamically. Note that this requires an in-depth understanding of the X Server internals. To extend the X Server:

1. Write the extension according to the standards set forth by the X Consortium. Extensions to the X Server must meet the following criteria:

   • Must not require changes to the X Server core.

   • Must be initialized at InitExtensions( ) time, which is after screen initialization but before input initialization. See the dix/main.c and ddx/mi/miinitext.c files.

   • Initialization must be accomplished with a single function call.

2. Populate a record in the extension.cf(D4nfb) file for the extension. See the manual page for details.

3. Create the extension object. For example, to create the XTrap object:

      cd extensions/server/xtrap
      make
      ld -r -e DEC_XTRAPInit -o -xtrap.o xtrapdi.o libxtrapext.a
   

   The xtrapdi.o module must be specified on the command line because it contains the DEC_XTRAPInit symbol.

When the server starts up, it initializes all its static extensions, then initializes all the dynamic extensions in the order in which they appear in the extension.cf file. No parameters are passed to the extension Init( ) routine.

The extension must be debugged using the dynamic X server since that is the only way to load dynamic extensions. You will need to modify the config and Imakefiles appropriately to statically link the extension into the X Server.