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7 Using the Ammasso 1100 with PXE Boot
PXE boot is a way to boot and load x86 based servers with a system image (or any other type
of program) that is served from another computer on the network. It is especially useful when
a unique operating system kernel image needs to be replicated across a number of servers.
Another use is if an operating system kernel image needs to be loaded on remote servers that
you do not have physical access to or which don't have an alternative boot device. PXE boot
is available only for devices that implement the Intel Preboot eXecution Environment (PXE)
specification. To determine if your server supports PXE network boot, see the hardware
manufacturer's documentation for your motherboard.
7.1 Theory of Operation
The Ammasso 1100 supports PXE boot by default. There is nothing specific you need to do
to enable the adapter
1
. When PXE boot support on the adapter is executed, the firmware
sends out a DHCP request, and waits to be assigned it’s own unique IP address as well as a
filename and server that will provide the network boot program (NBP). It then downloads
and runs the NBP. The firmware then downloads and runs the NPB.
For our testing, we used PXELINUX (
http://syslinux.zytor.com
) as our NBP.
When PXELINUX runs, it downloads a configuration file from the TFTP server to find out
the filenames of a linux kernel and associated ramdisk. PXELINUX then downloads them
and finally boots the actual Linux kernel we wish to execute.
Once the kernel boots, the network driver used by the PXE boot firmware is no longer
available. Therefore, if you use the network early in your kernel boot process, for instance to
remotely mount you root filesystem via NFS, the user either needs a network driver statically
built into the kernel image or provide a dynamically loaded one on the ramdisk. Since the
AMSO1100's driver is not statically bound into the default kernel image, the driver must be
included in the downloaded ramdisk and loaded into the running kernel during system start
up. After the AMSO1100 driver is loaded and configured, the Ethernet can be used:
i.e.
you may remotely mount the root filesystem via NFS.
The following section provides some basic information about configuring the Ammasso
adapter and software for use with PXE boot. The information provided is offered as a
reference, as there may be multiple ways to accomplish these tasks, depending on your
specific development environment.
7.2 Requirements
In order to use the Ammasso 1100 for PXE booting you will need the following set up. This
list is provided for reference. Examples are provided in later sections which describe how to
accomplish each of these.
1
The Ammasso AMSO 1100 uses Etherboot (
http://www.etherboot.org
) to provide the PXE support.
Etherboot generates an option ROM image that was factory flashed onto the network adapter.