Grub config for EFI and PXE boot

grub.cfg

set timeout=3

menuentry 'Linux diskless' --class os {

     insmod efi_gop
     insmod efi_uga

     # set server from option 66 (tftp-server-name) if not exist, use next_server
     if ! net_get_dhcp_option net_default_server ${net_default_interface} 66 string; then
         echo '        using next_server option instead.'
         set net_default_server=${pxe_default_server}
     fi

     echo '------------------------------------------------------------------------------'
     echo -n 'Interface:   '; net_ls_addr
     echo "HTTP Server: ${net_default_server}"
     echo '------------------------------------------------------------------------------'

     echo
     echo '    mm'
     echo ' /^(  )^\'
     echo ' \,(..),/'
     echo '   V~~V'
     echo

     echo "Loading Linux from http://${net_default_server}/vmlinz ..."
     linux (http)/vmlinuz console=tty1 console=ttyS0,9600n8 selinux=0 bond=bond0:eno1,eno1d1:mode=active-backup root=live:http://${net_default_server}/cc.squash rootovl=1 ro rd.live.image

     echo "Loading initial ramdisk from http://${net_default_server}/initramfs ..."
     initrd (http)/initramfs
}

Wow, thanks for documenting this! When booting UEFI PXE, TFTP times out when downloading the latest initrd file for Ubuntu 20.04 so HTTP is the only way to go. A google search reveals surprisingly little information on how to fix the problem. This gist helped me figure out how to go around the TFTP limitation.

chmod +r /yourpxe-bootpath/yourpxe-initrd.img