DRI User Guide : XF86Config file
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## 6. XF86Config file

The XFree86 configuration file is usually found in `/etc/X11/XF86Config`. This section describes the parts which must be specially set for the DRI.

First, the XF86Config file must load the GLX and DRI modules:

    	Section "Module"
    	...
    	# This loads the GLX module
    	    Load       "glx"
    	# This loads the DRI module
    	    Load       "dri"
    	EndSection

Next, the DRI section can be used to restrict access to direct rendering. A client can only use direct rendering if it has permission to open the `/dev/dri/card?` file(s). The permissions on these DRI device files is controlled by the "DRI" section in the XF86Config file.

If you want all of the users on your system to be able to use direct-rendering, then use a simple DRI section like this:

    	Section "DRI"
    	     Mode 0666
    	EndSection

This section will allow any user with a current connection to the X server to use direct rendering.

If you want to restrict the use of direct-rendering to a certain group of users, then create a group for those users by editing the `/etc/group` file on your system. For example, you may want to create a group called `xf86dri` and place two users (e.g., `fred` and `jane`) in that group. To do that, you might add the following line to `/etc/group`:

            xf86dri:x:8000:fred,jane

You have to be careful that the group id (8000 in this example) is unique.

Then you would use the following DRI section:

            Section "DRI"
                 Group "xf86dri"
                 Mode 0660
            EndSection

This would limit access to direct-rendering to those users in the `xf86dri` group (`fred` and `jane` in this example). When other users tried to use direct rendering, they would fall back to unaccelerated indirect rendering.

[Note that there is a known bug in XFree86 4.0 that prevents some changes to the DRI section from taking effect. Until this bug is fixed, if you change the DRI section, please also remove the `/dev/dri` directory with the `rm -rf /dev/dri` command.]

Finally, the XF86Config file needs `Device` and `Screen` sections specific to your hardware. Look in section 10: Hardware-Specific Information and Troubleshooting for details.

DRI User Guide : XF86Config file
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