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3. The Client

3.1 Ways to start up the client

There are two ways to start up the client. For testing purposes you may use a floppy disk to start up the client. The way to set up this floppy is described later on.

The second way, for production purposes, is to use a BOOT-ROM built into the ethernet card of the client. In most of the newer bios you will find a start up option called Network or Network-Booting in the CMOS SETUP. (In AMI-BIOS, for example, you have to set the 1st Boot Device to NETWORK in the Advanced CMOS Setup ) This option invokes the code in the ethernet's BOOT-ROM, which stablishes a connection to the server and makes a TFTP call. Be sure that the BIOS of the client's mainboard provides this featurer before going ahead.

Once established the connection and with the kernel loaded in the client's memory the two possibilities work the same way.

Testing with a floppy

The floppy for testing may be any empty one, without bad tracks. To make this floppy a boot-floppy you have to copy a kernel-image starting at the first block of the floppy. To do so use the dd command in the following way: 

 #:/ dd if=/kernel_image of=/dev/fd0
where kernel_image is a kernel-image prepared for this purpose. ( The Clients Kernel The Kernel of the Client)

Using an Ethernet card with special BootRom

This is the production version. To find Ethernet cards with a boot ROM you have the following possibilities:

  1. Buy cards that include a ready to run integrated EPROM
  2. Buy normal cards without EPROM, but with a socket for it, and plug in a programmed EPROM in it. To do this you will need an EPROM programmer.
Following is a list of sites where you may find utilities to do those things:
  1. www.disklessworkstation.com This site offers a range of products around diskless clients. You may find complete stations, prepared ethernet cards, EPROM programmers and EPROM and Flashdisks.
  2. www.ltsp.org
  3. www.slug.org.au/etherboot

3.2 The Kernel of the Client

The client's kernel needs some special options and has to be specially compiled in order to be transported and started up by an ethernet connection. Here we'll explain how to prepare the kernel for the client machines.

Options to be compiled into the kernel

  1. The option "CONFIG_NET" in "General Setup" and the option "CONFIG_INET" for TCP/IP must be activated.
  2. The option "CONFIG_IP_PNP" in "Networking options" has to be active, as well as "CONFIG_IP_PNP_BOOTP" if you want to use this protocol at start up.
  3. In the section "Network device support" you have to include support for you ethernet card.
It's very important to remember that in the client's kernel you can't use modules.

Preparing the kernel to work over ethernet

In order to activate the kernel to boot over the network you have to prepare it. The default program to do so is: mknbi - MaKe Network Bootable Image.

To generate a kernel image for the clients you may use the following program: 

mknbi-linux kernel-image > vmlinuz
Where kernel-image is the name of the original kernel and vmlinuz the name of the final image. This image has to be put into the directory specified in the /etc/dhcpd.conf file dhcpd .

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