How to Enable PXE in SLES 10 SP1 Virtualized Environments

by Jason Douglas

Problem:

Many people would like the option to use PXE in their SLES 10 SP1 virtualized environments, but Xen does not support PXE boot.

Solution:

To enable PXE in your fully virtualized guests, you can use a small CD ISO image as the boot device that contains code to emulate PXE for the virtual machine’s emulated network card.

Example:

To obtain and utilize this capability, do the following:

1. In a Web Browser go to: http://rom-o-matic.net/
2. Click on the 5.4.3 version under “Latest Production Release”
3. In the “Choose NIC / ROM type” drop down box, choose “rtl8139:rtl8139 — [0x10ec,0x8139]”
4. In the “Choose ROM output format” drop down box, choose “ISO bootable image without legacy floppy emulation (.iso)”
5. There’s no need to press the configure button, unless there’s some option you know you need (the defaults work just fine)
6. Press the “Get ROM” button. This will present you with a download dialog.
7. Download the iso to the Virtual Machine Host (domain0) file system.
8. In the virtual machine install tools, use this CD-Rom image as your OS installation CD.

Environment:

• A PXE server must be configured on your LAN before you can PXE boot
• This method of PXE booting only works for fully virtualized guests (no paravirtualized guests)
• In order to run fully virtualized guests in Xen, your cpu must be equipped with Intel VT or AMD-Virtualization technology.
• Some problems exist with the real-mode emulation in Xen 3.0.4 (included in SLES 10 SP1). As such, some PXE menus will not display in the guest. These limitations vary based on the manufacturer of your cpu. Below are the known limitations based on limited testing:
• AMD-V Processors:
• Does not work with PXE graphical menus (VESA)
• Works well with PXE text-based menus and PXE text prompts
• Intel VT Processors:
• Does not work with PXE graphical menus (VESA)
• Does not work with PXE text-based menus
• Works well with PXE text prompts

Due to real-mode emulation improvements, many of these limitations should be resolved in Xen 3.1.0 (and later).