Modification of the Asuswrt-Merlin guide for arm booting.

[alatnet]

Took a while to find this info but to, I believe, enable arm booting (either locally off the router or remotely from a separate server) you need to add the following lines to the dnsmasq.conf.add file in /jffs/configs/:

dhcp-match=set:arm64,60,PXEClient:Arch:11
dhcp-boot=tag:arm64,netboot.xyz-arm64.efi,,192.168.1.1

The client code for arm32 is hex code "A" or 10 in decimal where for arm64 it's hex code "B" or 11 in decimal.

so the full dnsmasq config would, more or less, be:

dhcp-match=set:bios,60,PXEClient:Arch:0
dhcp-boot=tag:bios,netboot.xyz.kpxe,,192.168.1.1
dhcp-match=set:efi32,60,PXEClient:Arch:2
dhcp-boot=tag:efi32,netboot.xyz.efi,,192.168.1.1
dhcp-match=set:efi32-1,60,PXEClient:Arch:6
dhcp-boot=tag:efi32-1,netboot.xyz.efi,,192.168.1.1
dhcp-match=set:efi64,60,PXEClient:Arch:7
dhcp-boot=tag:efi64,netboot.xyz.efi,,192.168.1.1
dhcp-match=set:efi64-1,60,PXEClient:Arch:8
dhcp-boot=tag:efi64-1,netboot.xyz.efi,,192.168.1.1
dhcp-match=set:efi64-2,60,PXEClient:Arch:9
dhcp-boot=tag:efi64-2,netboot.xyz.efi,,192.168.1.1
dhcp-match=set:arm64,60,PXEClient:Arch:11
dhcp-boot=tag:arm64,netboot.xyz-arm64.efi,,192.168.1.1

You dont necessarily need to use 192.168.1.1 (which is the router itself) if you are using a separate server, like me with a docker container for it, you can skip the curl of downloading the efi files, enabling tftp, and just point it to the server itself that is hosting netbootxyz.