Tty services are enabled in the later parts of the yocto build as a result of sources compiled earlier in the build process. As part of the compilation of these files a text file
presets/90-systemd.preset b/presets/90-systemd.preset
is analysed. If the line
enable getty@.service
is found then tty1 will be enabled at a later date when an appropariate symlink is added to the folder getty.target.wants. If the ‘enable’ is replaced with ‘disable’ in the file then no symlink will be added. One solution is therefore to create a suitable systemd_%.bbappend to patch the above line.