CLI:
java -Xmx512M -m jdk.packager/com.sun.javafx.tools.packager.Main -
makeall -appclass helloworld.HelloWorld
Error: JavaFx home directory is not known.

OBSERVATION:

class:: com.sun.javafx.tools.packager.PackagerLib
method::

culprit code:: from Line no:506 to Line no: 512
<CulpritCode>
  String jfxHome = System.getenv("JAVAFX_HOME");
        if (jfxHome == null) {
            jfxHome = System.getProperty("javafx.home");
        }
        if (jfxHome == null) {
            throw new PackagerException("ERR_MissingJavaFxHome");
        }
</CulpirtCode>

In the above code jfxHome is null.

Please have a look at attached screenshots.