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Configuring the Default X Server Loading Sequence

The default sequence for finding an X server and loading it into RAM allows the terminal to load an X server the first time it is powered on.

The Boot Monitor first attempts to download an X server from the following sources: TFTP (Trivial File Transfer Protocol), MOP (Maintenance Operations Protocol), NFS (Network File Service), local (PCMCIA card). If a PCMCIA card is installed in the terminal, NVRAM is still set to factory defaults, and the terminal has never booted from the network, the default order is local, TFTP, MOP, NFS.

If all attempts to load an X server fail, the Boot Monitor displays its prompt (>); you can enter a manual boot command.

The default X server loading sequence (listed in Table 4-1) automatically loads the first X server found in the default TFTP directory (usually /tftpboot). The default directory is defined by your implementation of TFTP.

After the request for an X server is answered by a host and is downloaded, no further requests are made. You can disable any of the requests.

Although the sequence uses predefined pathnames, you can use it to boot an X server located in another directory by linking one of the default pathnames to the X server's true location. For information about linking, see "Linking X Server Files".

Table 4-1 Default Server Loading Sequence
1. TFTP Requests: The Boot Monitor asks TFTP to download an X server. Potentially, the Boot Monitor can issue 16 different requests, as follows.
a. Requests to the boot host: The Boot Monitor directs the first series of requests to the boot host. The Boot Monitor tries the following pathnames in the order shown.
Relative pathnames: The first four requests use relative pathnames in the default TFTP X server directory, /tftpboot.
(1) A file named using the terminal's Ethernet address; for example, 0000A701395.
(2) A file named using the hexadecimal representation of the terminal's IP address. For example, C02B997E for the terminal with IP address 192.43.153.126.
(3) The file named using the terminal's product name and the terminal's memory size as a suffix. The memory size is stated in hundreds of kilobytes. For example, 8 megabytes is the same as 8000 kilobytes, yielding a suffix of 80. The resulting filename for an HMX in this example is Xncdhmx.80.
(4) The file named using the terminal's product name alone. For example, Xncdhmx.
Absolute pathnames: The second four requests use the same filenames, but absolute pathnames for the /tftpboot directory. These requests are included for versions of TFTP (such as the System V version) that do not use relative pathnames.
(5) For example, /tftpboot/0000A701395.
(6) For example, /tftpboot/C02B997E for the terminal with IP address 192.43.153.126.
(7) For example, /tftpboot/Xncdhmx.80 for an HMX family terminal with 8 megabytes of memory.
(8) For example, /tftpboot/Xncdhmx.
b. Requests to the broadcast address: The Boot Monitor broadcasts the 8 requests shown in (1) through (8) to the network.
2. MOP Requests: The Boot Monitor asks mop_mom to download an X server. Potentially, the Boot Monitor can issue two different multicast requests. The first host responding to a request sends a MOP volunteer packet to the terminal and the terminal attempts to download an X server.
a. The first request does not specify a filename.
b. The second request specifies the filename Xncdxxx.sys, where xxx represents the product name. For example, Xncdhmx.sys.
3. NFS Requests: The Boot Monitor asks NFS to download an X server. Potentially, the Boot Monitor can issue 16 different requests, as described for TFTP in Step 1 in this table. The default NFS X server directory is /tftpboot.
4. Local Booting: The Boot Monitor attempts to boot from a local file system on a PCMCIA card. If the terminal has a PCMCIA card, NVRAM contains factory default settings, and the terminal has not booted from the network, this attempt is made before the TFTP, MOP, and NFS requests.
5. Boot Monitor: If all attempts to load an X server fail, the Boot Monitor displays its prompt and waits for a command. You can enter a manual boot command.

Using remote configuration parameters, you can change the default download sequence. The configurable actions are:

Disabling Automatic Booting

To prevent the terminal from booting automatically, set the boot-automatically parameter to "false" (Setup -> Change Setup Parameters -> Booting -> Boot automatically at power up). If automatic booting is disabled, the terminal displays the Boot Monitor prompt instead of loading an X server. This parameter is saved in NVRAM.

Table 4-2 boot-automatically Parameter
Possible Values
Result
default true
true The Boot Monitor attempts to download an X server.
false The Boot Monitor does not attempt to download an X server.

Disabling Broadcast Requests for an X Server

If the boot host does not respond, the Boot Monitor directs X server download requests to the broadcast address.

To prevent broadcasting for an X server, set the boot-tcpip-broadcast-boot-request parameter to "false" (Setup -> Change Setup Parameters -> Booting -> TCP/IP Broadcast Boot Request). This parameter is saved in NVRAM.

Table 4-3 boot-tcpip-broadcast-boot-request Parameter
Possible Values
Result
default true
true The Boot Monitor attempts to download an X server by broadcasting.
false The Boot Monitor does not attempt to download an X server by broadcasting.

Disabling the MOP Request for an X Server

By default, after trying all of the TFTP requests, the Boot Monitor tries to download an X server using the MOP protocol.

To prevent MOP download requests, set the boot-mop parameter to "false" (Setup -> Change Setup Parameters -> Booting [NCDnet Boot Options section] -> Try MOP). This parameter is saved in NVRAM.

Table 4-4 boot-mop Parameter
Possible Values
Result
default true
true The Boot Monitor tries to download an X server using the MOP protocol.
false The Boot Monitor does not try to download an X server using the MOP protocol.

Disabling Selected TFTP or NFS Requests for an X Server

The parameters listed in Table 4-5 control the X server filenames that the Boot Monitor requests via TFTP or NFS during the default X server download sequence.

All parameters are "true" by default and are saved NVRAM. To disable a request, set its parameter to "false." For example: 


boot-tcpip-unit-address-with-path-file = false


Note:
There are no configuration parameters for the X server file named using the terminal's Ethernet address. These attempts can only be disabled by using the NVRAM utility. For more information, see Chapter 11, Boot Monitor and NVRAM .

Table 4-5 Download Sequence Parameters
Relative Pathname Requests
boot-tcpip-unit-address-file

(Setup -> Change Setup Parameters -> Booting [TCP/IP Boot Options section] -> Try TCP/IP Unit Address File)

The file named using the hexadecimal representation of the terminal's IP address.
boot-tcpip-product-name-and-memory-size-file (Setup -> Change Setup Parameters -> Booting [TCP/IP Boot Options section] -> Try TCP/IP Product Name and Memory Size File) The file named using the product name with the memory size as a suffix.
boot-tcpip-product-name-file (Setup -> Change Setup Parameters -> Booting [TCP/IP Boot Options section] -> Try TCP/IP Product Name File) The file named using the product name alone.
Absolute Pathname Requests
boot-tcpip-unit-address-with-path-file (Setup -> Change Setup Parameters -> Booting [TCP/IP Boot Options section] -> Try TCP/IP Unit Address with Path File) The file named using the hexadecimal representation of the terminal's IP address, prefixed with /tftpboot.
boot-tcpip-product-name-and-memory-size-with-path-file (Setup -> Change Setup Parameters -> Booting [TCP/IP Boot Options section] -> Try TCP/IP Product Name and Memory Size with Path File) The file named using the product name with the memory size of the terminal as the suffix and prefixed with /tftpboot.
boot-tcpip-product-name-with-path-file (Setup -> Change Setup Parameters -> Booting [TCP/IP Boot Options section] -> Try TCP/IP Product Name with Path File) The file named using the product name, prefixed with /tftpboot.

Specifying a Non-Standard X Server Filename

To specify a non-standard X server filename (not one of the names listed in Table 4-5), use the boot-custom-file parameter (Setup -> Change Setup Parameters -> Booting -> Custom File). This parameter is saved in NVRAM.

Table 4-6 boot-custom-file Parameter
Possible Values
Result
default nil
filename A non-standard name for the X server file.

Specifying a Non-Standard X Server Directory

To specify a non-standard X server directory, set the boot-nfs-directory parameter or boot-tftp-directory parameter. For details, see "Using TFTP for X Server Downloading" or "Using NFS for X Server Downloading".

Keeping the Terminal from Entering the Boot Monitor at Boot Time

By default, the Boot Monitor prompt appears when attempts to load an X server are unsuccessful. To configure the terminal to continue attempting to boot until it succeeds, set the boot-persistent-loading parameter to "true" (Setup -> Change Setup Parameters -> Booting -> Persist in Loading). This parameter is saved in NVRAM.

Table 4-7 boot-persistent-loading Parameter
Possible Values
Result
default false
false The Boot Monitor displays its prompt if all download attempts are unsuccessful.
true The Boot Monitor does not display its prompt if all attempts to load an X server are unsuccessful. It keeps trying the default or specified download sequence until you interrupt the process.

Configuring the Sequence of X Server Loading Methods

The default sequence of methods for finding and loading an X server is configured into NVRAM at the factory to allow the terminal to load an X server the first time it is powered on. The Boot Monitor tries these methods in the following order:

  1. TFTP

  2. MOP

  3. NFS

  4. The local file system on a PCMCIA card

If a PCMCIA card is installed, NVRAM values are set to their default values, and the terminal has not booted from the network, the default order is:

  1. The local file system on the PCMCIA card

  2. TFTP

  3. MOP

  4. NFS

When booting over a Token-Ring network, the MOP boot attempt is disabled automatically.

You can change the order of booting attempts through the Boot Monitor Setup menus, in a remote configuration file, or in Change Setup Parameters. The changes must be stored in NVRAM.

To specify the first method to try, set the value of the boot-desired-source parameter to the desired method (see Table 4-8). (Setup -> Change Setup Parameters -> Booting -> Primary Boot Source or Setup -> Change Quick Setup -> Booting -> Boot From). This parameter is saved in NVRAM.

Table 4-8 boot-desired-source Parameter
Possible Values
Result
default The terminal attempts to boot via TFTP first.
tftp
(tcpip) 		The terminal attempts to boot via TFTP first. ("tcpip" is included for backward compatibility and also results in first attempting TFTP booting.)
nfs The terminal attempts to boot via NFS first.
ncdnet The terminal attempts to boot via MOP over an NCDnet (DECnet) first.
local
(prom) 		The terminal attempts to boot first from a PCMCIA card. ("prom" is included for backward compatibility and results in attempting local booting first.)

To specify the second and third boot methods to use, set the boot-second-source (Setup -> Change Setup Parameters -> Booting -> Secondary Boot Source) and boot-third-source parameters (Setup -> Change Setup Parameters -> Booting -> Tertiary Boot Source). These parameters are saved in NVRAM.

The method specified in boot-second-source is used if the method specified in boot-desired-source does not succeed.

Table 4-9 boot-second-source Parameter
Possible Values
Result
default None
tftp
(tcpip) 		The terminal attempts to boot via TFTP. ("tcpip" is included for backward compatibility and also results in TFTP booting.)
nfs The terminal attempts to boot via NFS.
ncdnet The terminal attempts to boot via MOP over an NCDnet (DECnet).
local
(prom) 		The terminal attempts to boot from a local file system on a PCMCIA card. ("prom" is included for backward compatibility and results in local booting.)

The method specified in boot-third-source is used if the method specified in boot-second-source does not succeed.

Table 4-10 boot-third-source Parameter
Possible Values
Result
default None
tftp
(tcpip) 		The terminal attempts to boot via TFTP. ("tcpip" is included for backward compatibility and also results in TFTP booting.)
nfs The terminal attempts to boot via NFS.
ncdnet The terminal attempts to boot via MOP over an NCDnet (DECnet).
local (prom) The terminal attempts to boot from a local file system on a PCMCIA card. ("prom" is included for backward compatibility and results in local booting.)


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