title: In Linux, I am trying to write a user land app that can inspect some physical memory (for debug purposes)
body: <p>I am trying to write a user land app that can inspect some physical memory (for debug purposes).  </p>
  
  <pre><code>od -j &lt;0xknown_good_physical_address&gt; -N 256 /dev/mem 
  </code></pre>
  
  <p>(w/ <code>CONFIG_STRICT_DEVMEM=n</code>)  crashes the OS.</p>
  
  <p>functions <code>ioremap</code>, <code>phys_to_virt</code>, and <code>phys_to_page</code> don't exist in my <code>/usr/include</code> dir.  I researched and tried the <code>make headers_install</code> procedure but the functions still don't get into my usr/include dir.  AFAIK that means they're not available for user-land Apps. Does anyone know how to access physical memory from a user space app?  One more FYI, the physical address that I'm trying to read is a PCI BAR that I got from doing a <code>lspci -v</code> in the "memory at" line.</p>