1$(SECURE_BOOT_SIGNING_KEY): 2 @echo "Need to generate secure boot signing key." 3 @echo "One way is to run this command:" 4 @echo "$(ESPSECUREPY) generate_signing_key $@" 5 @echo "Keep key file safe after generating." 6 @echo "(See secure boot documentation for risks & alternatives.)" 7 @exit 1 8