[syslinux] trying to chainload the normal ubuntu pxe installer

[Warren Turkal]

Hi syslinux experts,

So, I have a pxe boot tree that looks something like this:
/menu.cfg
/linux
 /ubuntu
  /amd64
   /meerkat (contains a mirror of the netboot ubuntu image)

If I set the following in the appropriate stanza of my dhcpd.conf (for isc
dhcpd v3), I can boot the ubuntu installer:
filename "linux/ubuntu/amd64/meerkat/pxelinux.0";
next-server <tftp_server_ip>;

I would like to provide an unchanged ubuntu installer as an option from my
normal menu so that I can pull in new distributions very easily when they
are released. I changed the above dhcpd.conf config to the following:
site-option-space "pxelinux"; # appropriate definitions are included in the
config file
if exists dhcp-parameter-request-list {
  # Always send the PXELINUX options (specified in hexadecimal)
  option dhcp-parameter-request-list = concat(option
dhcp-parameter-request-list,d0,d1,d2,d3);
}
option pxelinux.magic f1:00:74:7e;
option pxelinux.configfile "menu.cfg";
option pxelinux.pathprefix "/";
filename "pxe_bin/pxelinux.0";
next-server <tftp_server_ip>;

In my menu.cfg, I tried the following to to chainload the ubuntu installer:
UI pxe_bin/menu.c32
PROMPT 0
MENU TITLE PXE Boot Menu

LABEL ubuntu_10_10_amd64
MENU LABEL Ubuntu 10.10 (Meerkat) AMD64
KERNEL pxe_bin/pxechain.com
APPEND <tftp_server_ip>::linux/ubuntu/amd64/meerkat/pxelinux.0

However, it locks the machine up when I try the chainload. Is it actually
possible to chainload pxelinux.0 like this?

I am using syslinux 4.0.1 file from Ubuntu 10.10 for my main pxelinux.0, and
I am using the file unchanged in the Ubuntu 10.10 netboot image. I would
think they'd be the same version, but I wanted to point it out in case it
presents a known problem.

Also, I cannot seem to find a way to change the pathprefix or the
configfile. I suspect that may cause problems if I get past the lockup. Are
there ways to override those values for the chainloaded pxelinux.0?

BTW, I am willing to consider gPXE solutions. I just didn't want to
complicate the config for my question.

I know that I can get it working by adding entries specifically in my menu,
but I am trying to boot an unchanged netboot image to make it easy to pull
in new distribution versions when they are released.

Thanks for your help,
wt