[syslinux] Chainloading pxe boot loaders and dhcp root-path option

[Matt Fioravante]

Is there anyway to set dynamically set dhcp options when chain loading
another pxe boot loader?

I'm setting up a pxelinux network install server and one operating system I
want to support is freebsd.

Freebsd has its own pxe loader called pxeboot that you can use. You just
have to boot it from tftp and set the root-path dhcp option (option 17) to
the location of your nfs server with the kernel and network filesystem.

I want to support multiple versions of freebsd (i386 and amd64) along with
Linux distros and others. The are hackish ways to accomplish this using
memdisk, but thats not a great idea if you want to have a 280MB live cd
image. The most elegant way I can see to do this is to chain load freebsd's
pxeboot loader from pxelinux. The problem is when you do this, the dhcp
root-path option is not set and defaults to /.

I need to be able to dynamically change this dhcp option before chain
loading into the next pxe boot loader. Essentiallly, I'd like to be able to
do something like this:

LABEL fbsd32
pxe pxeboot.0 dhcp-root-path=/nfsserv/freebsd/i386/root

LABEL fbsd64
pxe pxeboot.0 dhcp-root-path=/nfsserv/freebsd/amd64/root

Is this at all possible with pxelinux?

Thanks!