Diskless Booting: Difference between revisions

To create a GRUB PXE bootable image, you can follow the advice in the [http://www.gnu.org/software/grub/manual/grub.html#Network GRUB manual's Network chapter]. Several of the options to <tt>grub-mkimage</tt> did not exist in past versions and you need to upgrade if they aren't supported. If you compile from source, you can get all the <tt>*.{lst,mod,img}</tt> files you need in the source directory. In the case you compile your own GRUB you do not need to install it, just do commands like this:

 

./grub-mkimage -d . --format=i386-pc --output=core.img --prefix="(pxe)/boot/grub" pxe pxecmd

cat pxeboot.img core.img > grub2pxe

 

The final thing you need to do is setup a DHCP/BOOTP/TFTP server. I used <tt>dnsmasq</tt> which came preinstalled on my workstations, and seems to be widely available in distributions. It can easily be configured on the command line or in <tt>/etc/dnsmasq.conf</tt> which uses the same syntax as the long-form command-line options but without the leading dashes. You will need the following options:

 

interface=... # be careful what interface the dhcp server runs on!

bind-interfaces # *really* only bind that interface

enable-tftp

tftp-root=/tftp # or wherever

 

and there are other options to explore as well. Now make sure that you take <tt>grub2pxe,*.lst,*.mod</tt> from the GRUB source and put them in <tt>/tftp/boot/grub</tt> or equivalent. Also put your <tt>grub.cfg</tt> file there. The format of that is fairly simple. Here's the essence of what I use:

 

set timeout=0

set default=0

module /test

}

 

Make sure your kernel and modules appear in the tftp root, and you should be set to boot using your gPXE media, over a private network connection hooked up between workstations.

==The Direct Way==

 

 

Both of the options above involve using someone else's code to do the dirty work, which may be undesirable in some situations - licensing conflicts, technical problems (e.g. for "memdisk" the interrupt 0x13 hook won't work in protected mode) and possibly personal pride. Fortunately, writing your own PXE boot code isn't as difficult as it sounds.

*[http://download.intel.com/design/archives/wfm/downloads/pxespec.pdf PXE Specification]

 

[[Category:Bootloaders]]