iPXE script for deploying Ubuntu 20.04 autoinstall nocloud-net method

ubuntu2004.ipxe

#!ipxe
# ubuntu focal 20.04

# $seedfrom used to find the user-data and meta-data files by nocloud-net provider for cloud-init.
# the trailing slash is important, the cloud-init sticks 'meta-data' or 'user-data' right after it, without prepending a forward slash.
set seedfrom http://repo/files/ubuntu2004/

# $base url is where the vmlinuz and initrd live.
# they were fished out from the live-server iso file. the iso file is also in this directory.
set base http://repo/files/ubuntu2004

kernel ${base}/vmlinuz initrd=initrd autoinstall url=${base}/ubuntu-20.04-live-server-amd64.iso net.ifnames=0 biosdevname=0 ip=dhcp ds=nocloud-net;s=${seedfrom}
initrd ${base}/initrd
boot

I'm currently doing ipxe file for Ubuntu. I have done it works. Here's the block from the file.

ipxe
...
:install
kernel ${base-url}/vmlinuz initrd=initrd autoinstall url=${iso-url} net.ifnames=0 biosdevname=0 ip=dhcp ds=nocloud-net;seedfrom=${seed-url}/ubuntu.seed
initrd ${base-url}/initrd
boot

I see in ubuntu iso in grub.config there's a block

grub_platform
if [ "$grub_platform" = "efi" ]; then
menuentry 'Boot from next volume' {
exit 1
}
menuentry 'UEFI Firmware Settings' {
fwsetup
}
else
menuentry 'Test memory' {
linux16 /boot/memtest86+.bin
}
fi

I'd like in my ipxe file to make a menu option to start memtest. How I can make this?
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