6.1. The Boot Process

When an X Terminal is booted from a host on the network, it may either use bootp or rarp to determine ip and host addresses, or it may store those values locally in NVRAM on the terminal. The advantage to using bootp is that the host information and ip addresses may be stored centrally in a single configuration. An advantage to using the values locally on the client system is that it allows for a more fine-grained control over tcp/ip and host information.

Assuming that host and ip address information is properly configured for the X Terminal, step two in the boot process is for the X Terminal to load its operating system and core fonts. In order to do this, the client needs to know the full path to the OS image and system configurations and base fonts. It needs to have a boot method specified for fetching these files. On most systems, that is tftp or nfs. Last, the X Terminal needs to know which will be managing the XDMCP communication ( i.e., the system from which client applications will be deployed ). All of this information is stored in NVRAM on the X Terminal.

Step three in the boot process occurs when the X Terminal connects to the client machine. Most X Terminals can send a direct or indirect query to an xdmcp session manager on a network. In an indirect query, all available xdmcp session managers will respond and display a menu of possible hosts. In the case of a direct query, xdm on the host system runs the Xsetup script which sets up the display for the login screen and provides the xlogin widget which requires a valid userid and password to login and start an xdmcp session.