Syslinux - Jul 2003 - etherboot vs. pxelinux (was: Windows Remote Install)

Hi,

"David Ehrmann" <exobyte at bigvalley.net> schrieb am 10.07.03
11:02:54:
> I've been doing that for a while, but I seem to be finding conflicting
> information.  Some sources focus on the boot ROM aspect of etherboot
> while others think etherboot is an alternative to PXE.  Correct me if
I'm
> wrong, but it seems like there is etherboot the program and etherboot the
> protocol.
pxelinux is a PXE boot loader, it depends on a PXE-Rom installed in the
network card. This loads the config file, a kernel (or memdisk, etc.) and
the initrd. pxelinux itself is not network card dependent, since the
network card specific code is in the PXE rom.

etherboot is basically a network card rom. It was originally designed to
be burned to the network card rom, replacing anything on the rom 
(including the PXE code). etherboot works with tagged images containing
the configuration, the kernel and initrd in one file, and is usually
created specifically for a network card. One way to boot with etherboot
is also to boot the etherboot code via the pxe rom, and then continuing
as above (basically: Replacing the PXE code with etherboot code, and
continue as if this etherboot code was burned to the network card
rom).

So pxe and etherboot have some connections, if you talk about 
pxelinux you should not use anything from etherboot, since this
uses a quite different approach. It's at first quite confusing to see
'etherboot supports pxe' while it only uses pxe as a piggyback to
load itself, and then taking over full control over the network card.

I hope this cleared some things about etherboot vs. pxelinux.

Regards,

Josef
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That's a good summary, Josef
> So pxe and etherboot have some connections, if you talk about 
> pxelinux you should not use anything from etherboot, since this
> uses a quite different approach.
Well.. there is *some* overlap, and so it can be confusing to work out
the two systems actually do. Configuration achieves the same end, but in
a different way, so at the moment, one generally uses one OR the other,
not both.
> It's at first quite confusing to see 'etherboot supports pxe'
while
> it only uses pxe as a piggyback to load itself, and then taking over
> full control over the network card.
Put another way, etherboot is currently loadable *via* PXE; recently
support has been added for the UNDI driver. Etherboot *may* soon turn
into a full replacement for PXE, so that e.g. pxelinux can run on top
of Etherboot.  It's not there yet, but all the hard stuff is done.

In general, any bootloader can load any other bootloader - it's common
for developers to use an existing version of a loader to test how a
newer version then loads the target OS.  Consider that one might also
fix buggy PXE and BIOS firmware by the vendor's PXE code loading
Etherboot, which could support a fixed open source PXE environment,
which can chain pxelinux, which uses MEMDISK to load Windows... you get
the idea.