title: Linux: device appears in /dev but cannot be accessed
body: <p>I have created a Linux device driver and can add it to the <code>system (insmod, mknod)</code>. When I look in <code>/dev</code> I see it listed as <code>camerax</code>:</p>
  
  <pre><code>ls -l /dev/camerax
  crw-r--r--    1 root     root      245,   0 Jun 27 17:19
  </code></pre>
  
  <p>Even so, I cannot access it. Whatever I do, I get an error.</p>
  
  <p>For example:</p>
  
  <pre><code>int fd = open("/dev/camerax", O_RDONLY);
  
  printf("%d [%s]\n", fd, strerror(errno));
  </code></pre>
  
  <p>Generates:</p>
  
  <pre><code>-1 [No such device or address]
  </code></pre>
  
  <p>I'm running as a super user. Any suggestions?</p>