title: MACHINE_EXTRA_RDEPENDS vs MACHINE_ESSENTIAL_EXTRA_RDEPENDS
body: <p>I wrote a hello world device driver recipe and when i am trying to install it in the root file system, using the following variable in qemux86-64.conf</p>
  
  <pre><code>MACHINE_EXTRA_RDEPENDS = += " kernel-module-hello"
  </code></pre>
  
  <p>The above line is not inserted in the module in root file system but the below line does</p>
  
  <pre><code>MACHINE_ESSENTIAL_EXTRA_RDEPENDS += " kernel-module-hello"
  </code></pre>
  
  <p>Can anyone tell me what is the difference between these both variables. Which one should be used when?</p>