Hi @Aaron Hicks,

We have limited support knowledge on PXE boot and on the OS that you're using. I might not be able to provide any guidance. We probably might need to wait and seek help from the public if they have any experience on your issue. 

Meanwhile, have you tried Legacy BIOS Boot Mode? Are there similar models you have that are successful? 

Screenshot of Legacy boot:

We only have two of these Dell PowerEdge XE8545 in datacentre so we don't have any similar models to compare.

I've tested just tested legacy boot, hangs at Probing EDD. However we have some hosts in this environment which don't boot with legacy bios and we'd strongly prefer to solve the UEFI PXE boot issue for consistency.

Ah, we also need to boot off a tagged VLAN which isn't supported by Legacy boot mode.

we also need to boot off a tagged VLAN which isn't supported by Legacy boot mode.
For this, I assume you need to shrink the size of the disk.

The dnsmasq config that kicks it off, I think the problem is occuring between loading the bootfile indicated by dnsmasq and loading the kernel and ramdisk from PXE

# cat /etc/dnsmasq.conf 
# NOTE(yoctozepto): ironic-dnsmasq is used to deliver DHCP(v6) service
# DNS service is disabled:
port=0

interface=bond0.1152
bind-interfaces

dhcp-range=10.64.156.1,10.64.156.254,255.255.248.0
dhcp-sequential-ip

dhcp-option=option:tftp-server,10.64.155.1
dhcp-option=option:server-ip-address,10.64.155.1
dhcp-option=210,/tftpboot/
dhcp-option=option:bootfile-name,pxelinux.0

dhcp-hostsdir=/etc/dnsmasq/dhcp-hostsdir

How small does the disk need to be, and where is the documentation on this requirement?

Here's the default pxelinx.cfg configuration:

# cat pxelinux.cfg/default 
default introspect

label introspect
kernel ironic-agent.kernel

append initrd=ironic-agent.initramfs ipa-inspection-callback-url=http://10.64.152.10:5050/v1/continue systemd.journald.forward_to_console=yes ipa-collect-lldp=1 ipa-inspection-collectors=default,logs,pci-devices ipa-inspection-benchmarks=

ipappend 3

 And here's the size of the kernel and ramdisk image:

# ls -lh ironic-agent.*
-rw-r--r-- 1 ironic ironic 384M Jul 7 22:10 ironic-agent.initramfs
-rw-r--r-- 1 ironic ironic 9.8M Jul 7 22:10 ironic-agent.kernel

Hi, might I suggest that you try another NIC and PXE boot?

I'm now running into issues with preserving the VLAN when iPXE chain loads after PXE, but I think this is a problem with iPXE and not the hardware. Anyone else following this problem will probably want to follow up with:

- https://bootsha.medium.com/how-to-pxe-boot-a-server-using-tagged-vlan-9d822adb8104

- https://github.com/ipxe/ipxe/issues/369