[syslinux] Network booting FreeBSD with gpxelinx almost works (fwd)

[Daniel Feenberg]

We have been network booting FreeBSD for some time with pxeboot. But now 
we would like to have menu of OSs to boot and got the idea somewhere that 
gpxelinux could do that for us. We copied gpxelinux.0 from the 
syslinux-4.02 distribution and replaced "pxeboot" with "gpxelinux.0" in 
the dhcpd.conf file. Indeed with a configuration file in pxelinux.cfg like 
this:

   default freebsd
   label freebsd
     PXE pxeboot

and the root path still specified as a DHCP option, FreeBSD 8.1 does boot. 
If I replace the first line with:

   UI menu.c32

the client does display the menu but if one hits return to select the 
single item offered the client merely hangs for a minute, then announces 
"boot failure". I am guessing that once the UI is interposed, somehow the 
root path isn't getting transmitted to pxeboot. All the other gpxelinux 
boot kernels seem to expect the information about the root filesystem to 
be specified in the pxelinux.cfg file, rather than in dhcpd.conf. Does 
anyone have experience with this? The various web posting I have found 
linking FreeBSD to gpxelinux are about installations from ISO files over 
the net.

In the syslinux mailing list there is an unanswered  posting which is similar 
to this:

   http://syslinux.zytor.com/archives/2006-February/006582.html

but we do not modify vfs.root.mountfrom, or rename pxeboot.

I found this in the "changes in 3.36":

  > PXELINUX: Unbreak chainbooting FreeBSD (and possibly others.)

but I haven't found any information about implementing chainbooting
for FreeBSD.

There are a number of web pages showing how to install FreeBSD from an ISO 
image over the net - this is not what we want to do. We are currently 
using the built-in facilities of FreeBSD to boot a working system over the 
net and wish to continue without a major upheaval. Our setup is described 
at:

   http://www.nber.org/sys-admin/FreeBSD-diskless.html

Daniel Feenberg
NBER