title: Whats meaning of obj-y += something/ in linux kernel Makefile?
body: <p>I understand the meaning of </p>
  
  <pre><code>obj-$(CONFIG_USB)       += usb.o
  </code></pre>
  
  <p>if CONFIG_USB  is y then usb.o will be compiled. So now how to understand this  </p>
  
  <pre><code>obj-y               += something/
  </code></pre>