pxebooting different versions/variants of FreeBSD

[Dura Zell]

Hi

I'm planning to setup a machine wich should provide several versions of 
FreeBSD and their respective amd64 and x86 variants. Addtionally the 
user should have the option to install the selected os(es) locally.

Currently I'm using pxelinux.0 from syslinux to create a text-based menu 
for the user to select the desired option like this:

1. diskless boot FreeBSD 8.0 amd64
2. Install FreeBSD 8.0 amd64 locally
3. diskless FreeBSD 8.0 x86
4. Install FreeBSD 8.0 x86 locally
5. Recovery System

In fact I'm planning to provide some more FreeBSD versions and some 
linux distros too, but there is no problem with that currently and the 
above example is the one I'm using for testing now.

gpxelinux chains the regular /boot/pxeboot and gives it control to do 
the rest wich works fine and I'm able to boot into a testbed 
installation of FreeBSD.

Unfortunately for me, pxeboot relies on the dhcp-option "root-path" to 
be set to know where to find where the rootfs sits. As the user should 
be able to select the version to install freely, I can't preconfigure 
this on a machine basis (by using the mac address as identifier).

Is there a way to circumvent the need need of the dhcp option 
"root-path" and set it instead manually via a config file or as 
parameter? If not: How can I achieve my goal of pxebooting the different 
versions of FreeBSD?

with kind regards,

Sven