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iPXE boot rom

This is a small set of scripts that simply download and build a bootrom of iPXE that can be used as an alternative bootrom in VirtualBox. This consists of two parts:

  • The ROM that really can do only one thing: Load the 'full' ipxe from a website.
  • The full iPXE that will load the real menu from a website.

Why?

I found that building a working ROM is harder than it seems. Without any configuration the image will be too large.

So in order to make this work a LOT of features had to be disabled. This is done by creating a set of overrules that are located in the general-rom.h file

But then we have a severely limited version of iPXE. So what I do here is I then load a full featured version of iPXE from a website and then load the menu I want. This way you have the boot strap info in the (limited) rom and you get to use all of the power of iPXE.

VirtualBox LAN boot ROM Size

On this site https://gist.github.com/robinsmidsrod/4001104 it says this about the size:

include/iprt/cdefs.h
1888:#define _64K                    0x00010000

src/VBox/Devices/PC/DevPcBios.h
43:#define VBOX_LANBOOT_SEG            0xe200

src/VBox/Devices/PC/DevPcBios.cpp
1348:                if (cbFileLanBoot > _64K - (VBOX_LANBOOT_SEG << 4 & 0xffff))

$ perl -e 'printf "%x\n", 0x10000 - 0xe200 << 4 & 0xffff'
e000
$ perl -e 'printf "%d\n", 0x10000 - 0xe200 << 4 & 0xffff'
57344

So the conclusion is that the maximum size of a ROM is 0xE000 bytes (= 57344)

Building

Make sure the right URLs have been configured: At the top of the Makefile your should set the BASEURL to the right spot.

I run this on my CentOS system and simply type

make

You will have two files:

  • 8086100e.rom which is the rom file for the virtual machine (VirtualBox with Extension Pack).
  • menuloader.pxe which is the full featured ipxe that will load the actual menu.

Now put the menuloader.pxe and your menu.ipxe script on the URLs you configured and add the ROM into the VirtualBox VM. You can double check the urls present in script-rom.ipxe and script-full.ipxe.

Installing the new LAN boot ROM into VirtualBox

See: http://etherboot.org/wiki/romburning/vbox

8086100e.rom is the LAN boot ROM for the Intel PRO/1000 MT Desktop (82540EM) which is the default when you have the VirtualBox Extension Pack installed.

  • Create a virtual machine ( Here I call it "Hadoop Client" ) and do settings that you want to boot from network
  • Copy the 8086100e.rom into the directory of that VM
  • Add the ROM image to the VM config:

Under Linux:

  • vboxmanage setextradata "Hadoop Client" VBoxInternal/Devices/pcbios/0/Config/LanBootRom 8086100e.rom

Under Windows:

  • "c:\Program Files\Oracle\VirtualBox\VBoxManage.exe" setextradata "Hadoop Client" VBoxInternal/Devices/pcbios/0/Config/LanBootRom "C:\VirtualBox VMs\Hadoop Client\8086100e.rom"