Trying to chainload iPXE with full feature set from a lesser featured one, whilst still being able to boot non-supported cards with UNDI

dhcpd.conf

ddns-update-style none;
deny bootp; #default
authoritative;

include "/etc/dhcp/ipxe-option-space.conf";

# GREEN (private network)
subnet 10.1.1.0 netmask 255.255.255.0 {
    range 10.1.1.100 10.1.1.199;
    option subnet-mask 255.255.255.0;
    option routers 10.1.1.1;                        # firewall.smidsrod.lan

    default-lease-time 3600;
    max-lease-time 86400;

    option domain-name "smidsrod.lan";
    option domain-search "smidsrod.lan";
    option domain-name-servers 10.1.1.1;            # firewall.smidsrod.lan

    option ntp-servers 132.163.97.3,132.163.97.2;   # time.nist.gov
    option log-servers 10.1.1.2;                    # core.smidsrod.lan
    option lpr-servers 10.1.1.8;                    # laserjet.smidsrod.lan

    include "/etc/dhcp/ipxe-green.conf";
}

use-host-decl-names on;

include "/etc/dhcp/static.conf";

ipxe-green.conf

# For information on valid values for option arch, see these links:
# https://git.ipxe.org/ipxe.git/commitdiff/af9afd0a86aeac1eed28b5028c3de669515fc7fc
# https://git.ipxe.org/ipxe.git/blob/HEAD:/src/include/ipxe/dhcp.h#l275
# https://www.rfc-editor.org/errata_search.php?rfc=4578
#
# I like to use native iPXE drivers (they're faster and more stable), so
# give ipxe.pxe/ipxe.efi to all non-iPXE clients, use undionly.kpxe/snponly.efi
# only if you have unsupported or misbehaving NICs.

allow bootp;
allow booting;
next-server 10.1.1.2; # core.smidsrod.lan

# Disable ProxyDHCP, we're in control of the primary DHCP server
option ipxe.no-pxedhcp 1;

# Make sure the iPXE we're loading supports the features we need, if not
# load a full-featured version.  See ipxe-option-space.conf for definitions.
if    exists ipxe.http
  and exists ipxe.menu
  and exists ipxe.nfs           # NB: not enabled in iPXE by default
  and (
        ( exists ipxe.pxe
      and exists ipxe.bzimage
      and exists ipxe.elf
      and exists ipxe.comboot   # NB: not enabled in iPXE by default
      and exists ipxe.iscsi
        ) or (
          exists ipxe.efi
        )
      ) {
    filename "nfs://nas.smidsrod.lan/raid/boot/boot.ipxe";
    #filename "http://boot.smidsrod.lan/boot.ipxe";
} elsif option arch = 00:09 { # EFI BC
} elsif option arch = 00:08 { # EFI Xscale
} elsif option arch = 00:07 {
    # EFI x86-64 (Intel x86 64-bit EFI mode)
    # - most commonly used on newer hardware
    filename "ipxe-x64.efi";
    #filename "snponly-x64.efi";
} elsif option arch = 00:06 {
    # EFI IA32 (Intel x86 32-bit EFI mode)
    # - almost never seen in the wild
    filename "ipxe-x86.efi";
    #filename "snponly-x86.efi";
} elsif option arch = 00:05 { # Intel Lean Client
} elsif option arch = 00:04 { # Arc x86
} elsif option arch = 00:03 { # DEC Alpha
} elsif option arch = 00:02 { # EFI Itanium
} elsif option arch = 00:01 { # NEC/PC98
} else {
    # Intel x86PC (Intel x86 32-bit legacy BIOS mode)
    # - technically option arch = 00:00, but we use it as fallback
    filename "ipxe.pxe";
    #filename "undionly.kpxe";
}

ipxe-option-space.conf

# Declare the iPXE/gPXE/Etherboot option space
option space ipxe;
option ipxe-encap-opts code 175 = encapsulate ipxe;

# iPXE options, can be set in DHCP response packet
option ipxe.priority         code   1 = signed integer 8;
option ipxe.keep-san         code   8 = unsigned integer 8;
option ipxe.skip-san-boot    code   9 = unsigned integer 8;
option ipxe.syslogs          code  85 = string;
option ipxe.cert             code  91 = string;
option ipxe.privkey          code  92 = string;
option ipxe.crosscert        code  93 = string;
option ipxe.no-pxedhcp       code 176 = unsigned integer 8;
option ipxe.bus-id           code 177 = string;
option ipxe.san-filename     code 188 = string;
option ipxe.bios-drive       code 189 = unsigned integer 8;
option ipxe.username         code 190 = string;
option ipxe.password         code 191 = string;
option ipxe.reverse-username code 192 = string;
option ipxe.reverse-password code 193 = string;
option ipxe.version          code 235 = string;
option iscsi-initiator-iqn   code 203 = string;

# iPXE feature flags, set in DHCP request packet
option ipxe.pxeext    code 16 = unsigned integer 8;
option ipxe.iscsi     code 17 = unsigned integer 8;
option ipxe.aoe       code 18 = unsigned integer 8;
option ipxe.http      code 19 = unsigned integer 8;
option ipxe.https     code 20 = unsigned integer 8;
option ipxe.tftp      code 21 = unsigned integer 8;
option ipxe.ftp       code 22 = unsigned integer 8;
option ipxe.dns       code 23 = unsigned integer 8;
option ipxe.bzimage   code 24 = unsigned integer 8;
option ipxe.multiboot code 25 = unsigned integer 8;
option ipxe.slam      code 26 = unsigned integer 8;
option ipxe.srp       code 27 = unsigned integer 8;
option ipxe.nbi       code 32 = unsigned integer 8;
option ipxe.pxe       code 33 = unsigned integer 8;
option ipxe.elf       code 34 = unsigned integer 8;
option ipxe.comboot   code 35 = unsigned integer 8;
option ipxe.efi       code 36 = unsigned integer 8;
option ipxe.fcoe      code 37 = unsigned integer 8;
option ipxe.vlan      code 38 = unsigned integer 8;
option ipxe.menu      code 39 = unsigned integer 8;
option ipxe.sdi       code 40 = unsigned integer 8;
option ipxe.nfs       code 41 = unsigned integer 8;

# Other useful general options
# http://www.ietf.org/assignments/dhcpv6-parameters/dhcpv6-parameters.txt
option arch code 93 = unsigned integer 16;

@robinsmidsrod nice, it is easier to follow, and I can't see any way that this can create any negative results. Awesome!

I was trying to find how to chainload using ipxe and not dhcp. I ended up making this script:

#!ipxe

:version_check
set latest_version 1.20.1+ (g3662)
echo ${cls}
iseq ${version} ${latest_version} && goto version_up2date ||
echo
echo Updated version of iPXE is available:
echo
echo Running version.....${version}
echo Updated version.....${latest_version}
echo
echo Attempting to chain to latest version...
chain --autofree http://pxe.local/ipxe.lkrn ||

:version_up2date

Have spent some time to create almost identical config for those in need of a Proxy DHCP setup using dnsmasq

In there we also discussed that EFI now supports iSCSI by default, so it would probably make sense to move and exists ipxe.iscsi to directly after the and exists ipxe.menu line