title: Kernel module compilation and KBUILD_NOPEDANTIC
body: <p>I've noticed that recent kernels (starting from 2.16.24?) don't like if <code>CFLAGS</code> is changed in external module Kbuild file. If <code>CFLAGS</code> is changed you'll be issued the following error by Linux kernel Kbuild system:</p>
  
  <pre><code>scripts/Makefile.build:46: *** CFLAGS was changed in "/some/path". Fix it to use EXTRA_CFLAGS.  Stop.
  </code></pre>
  
  <p>From <a href="http://www.mail-archive.com/git-commits-head@vger.kernel.org/msg26519.html" rel="noreferrer">here</a>:</p>
  
  <blockquote>
    <p>External modules have in a few cases modifed gcc option
        by modifying CFLAGS. This has never been documented and
        was a bad practice.</p>
  </blockquote>
  
  <p>Additional <code>email</code> from LKML.</p>
  
  <p>Why is it bad idea? What is rational?</p>