[syslinux] Chain-loading from WDS to PXELinux on a different tftp server

[Luke Ledgerd]

Thanks for your email. Yes it does provide some insight into why I could hack a Linux DHCP server into providing enough PXE boot information for PXE 3 clients but PXE 2.1 were happy (ROMs under many circumstances need to use proxy dhcp 4011 - as documented by IBM on the link I shared earlier). 

It appears only the most latest Dell business systems have EFI 64 support, and the best you can expect from models 2-3 years old is Legacy PXE ROM and only EFI support for booting from USB/HDD - correct me if I'm wrong.

Moving on from that we NEED to use WDS as we have chosen SCCM+WDS to do our M$ deployments.
Many people say SCCM / Windows PE is "flakey" (source whirlpool.net.au) but orders are orders. It does automate the deployment of masses of Microsoft workstations, provided you spend twice as long fiddling with the task sequences etc 
http://forums.whirlpool.net.au/archive/2034700

"Pity that SCCM has got pxeboot.com hard coded in SMS pe.dll (the usual MS vision of the world, us or nothing...)"
http://reboot.pro/topic/20145-pxe-chain-sccm-2012-r2-wds/
Hence why we don't use SCCM to manage "unknown computers", but let WDS take over.

The goal to use the other TFTP server is because it's a NAS and it's fast. The SCCM server on Hyper-V + iscsi back to the same NAs, it's improving year by year.

I think I'd like to ask for a feature request to allow pxechn.c32 to work with EFI too and to have the ability for PXELinux to have a ROOT path variable (kind of like gpxelinux.0) that can either have HTTP or TFTP urls. That would be a very useful addition to PXELinux.

Because of this I'm going to have to move over all the work setting up a nice PXELinux boot menu with all our support tools and goodies over to the WDS \RemoteInstall folder and have Microsoft NTFS file system over iscsi be use deploying everything. I would give my left arm to avoid that if I could.

Peter, your thoughts?

Cheers,

Luke

-----Original Message-----
From: Syslinux [mailto:syslinux-bounces at zytor.com] On Behalf Of Spike White
Sent: Saturday, December 27, 2014 4:32 AM
To: For discussion of Syslinux and tftp-hpa
Subject: [syslinux] Chain-loading from WDS to PXELinux on a different tftp server

Luke, I have considerable experience with this.  We use WDS at work for PXE (MS-centric shop).  I use pxelinux at home.

I've got WDS working in our test lab w/ UEFI.  As you state, it strongly wishes to do proxyDHCP (port 4011).  More on this in a bit.

It's quite common to segregate the DHCP server from the TFTP server.
Commonly,
it's because DHCP services is maintained why one team and PXE boot by another.

What you're desiring is somewhat obscure -- you're wanting your WDS server to provide the DHCP service, while you have another server provide TFTP.

Normally, it'd be the other way around; some other server would be providing DHCP and WDS would be providing TFTP/PXE.  I'd argue for your setup what you really want is straight MS DHCP service (to provide DHCP).  and point it to your NAS (for TFTP).

Except that wouldn't work for your known servers.

About proxyDHCP.  I'm loading wdsmfg.efi as the network boot program (NBP).
So some of my tested configurations do the std D-O-R-A to the DHCP server and then immediately do a TFTP read request from my TFTP server.  Loading the boot\x64\wdsmgfw.efi.

However, then it does RA - RA - RA to the WDS server (proxyDHCP port 4011).
I'm convinced it's the wdsmgfw.efi that's doing this.

Here's the best config I found:
   TFTP Server Name (option 66) -- set to WDS server's IP address
   Domain Name (option 15) -- set to DNS domain
   File Name    set to boot\x64\wdsmgfw.efi
   Next Server  set to WDS server's IP address

Also, you might try this config:
   Boot File Name (option 67) -- set to boot\x64\wdsmgfw.efi
   TFTP Server Name (option 66) -- set to WDS server's IP address
   Domain Name (option 15) -- set to DNS domain
   File Name    set to boot\x64\wdsmgfw.efi
   Next Server  set to WDS server's IP address

That second config doesn't work for me, because of a bug in the EFI boot code of my Intel and Broadcom NICs.  It interprets option 67 as
boot\x64\wdsmgfw.efi\377 .  (Don't want to re-hash this; been discussed thoroughly in this mailing list before).

Spike White
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