Diskless Booting: Difference between revisions

== The GRUB Legacy Way ==

First, you have to create a floppy with [[GRUB Legacy]] configured for net support. You can either get a floppy image from http://i30www.ira.uka.de/%7Eud3/mkgrubdisk/ or download a current source release of [[GRUB Legacy]] and <tt>./configure</tt> it with support for your NIC.

Although this is the simplest way, GRUB Legacy doesn't seem to support all network cards.

== The PXELINUX Way ==

This file is loaded with a <tt>memdisk initrd=grub.ima</tt> syntax, which will cause pxelinux to load memdisk and grub.ima through TFTP. Memdisk will hook interrupt 0x13, and boot the disk image that way. (However, not all [[GRUB Legacy]] disk images seem to access floppies through bios. If you've got such an image you're stuck.)

At this point, you can make changes to the grub.ima disk image, and put a [[GRUB Legacy]] config file and your kernel's binaries there.

== The gPXE +GRUB2 GRUB Way ==

[[GRUB-legacy]] doessince notversion support newer network cards, but if you can use [http://www.gnu.org/software/grub GRUB2] then you2 can piggy-back on [http://www.etherboot.org/wiki/start gPXE]'s network support., unlike GRUB Legacy that does not support newer network cards. The gPXE project is a currently-maintained, open source, free network bootloader. It is easy to get gPXE ISO, disk, or USB disk images from their website, but there is a workaround you need to apply in order to get GRUB2GRUB to successfully load.

gPXE supports multiboot, but if it detects a multiboot image then it will not provide PXE services. Unfortunately, it detects your generated GRUB2GRUB image as multiboot, and the only way I found to get around this was to recompile gPXE without multiboot support. Recompiling gPXE is easy: unpack it, <tt>cd src; make</tt>. Before you do that, you will want to edit <tt>src/config/defaults/pcbios.h</tt> and comment out the line that defines <tt>IMAGE_MULTIBOOT</tt>. After compiling you should be left with <tt>bin/gpxe.{dsk,iso,usb}</tt> which you can write to disk or CD.

To create a GRUB2GRUB 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]. Keep in mind that GRUB2 is in flux, and severalSeveral of the options to <tt>grub-mkimage</tt> did not exist in past versions. and Iyou recommendneed gettingto theupgrade latestif versionthey andaren't compilingsupported. fromIf source,you it'scompile fairlyfrom straightforwardsource, and then you are leftcan withget all the <tt>*.{lst,mod,img}</tt> files you need in the source directory. In the case you compile your own GRUB2GRUB you do not need to install it, just do commands like this:

and there are other options to explore as well. Now make sure that you take <tt>grub2pxe,*.lst,*.mod</tt> from the grub2GRUB 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: