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| <section id="nuttx-file-system"> |
| <h1>NuttX File System<a class="headerlink" href="#nuttx-file-system" title="Permalink to this headline"></a></h1> |
| <p><strong>Overview</strong>. NuttX includes an optional, scalable file system. |
| This file-system may be omitted altogether; NuttX does not depend |
| on the presence of any file system.</p> |
| <p><strong>Pseudo Root File System</strong>. A simple <em>in-memory</em>, <em>pseudo</em> file |
| system can be enabled by default. This is an <em>in-memory</em> file |
| system because it does not require any storage medium or block |
| driver support. Rather, file system contents are generated |
| on-the-fly as referenced via standard file system operations |
| (open, close, read, write, etc.). In this sense, the file system |
| is <em>pseudo</em> file system (in the same sense that the Linux |
| <code class="docutils literal notranslate"><span class="pre">/proc</span></code> file system is also referred to as a pseudo file |
| system).</p> |
| <p>Any user supplied data or logic can be accessed via the |
| pseudo-file system. Built in support is provided for character and |
| block <a class="reference external" href="#DeviceDrivers">drivers</a> in the <code class="docutils literal notranslate"><span class="pre">/dev</span></code> pseudo file |
| system directory.</p> |
| <p><strong>Mounted File Systems</strong> The simple in-memory file system can be |
| extended my mounting block devices that provide access to true |
| file systems backed up via some mass storage device. NuttX |
| supports the standard <code class="docutils literal notranslate"><span class="pre">mount()</span></code> command that allows a block |
| driver to be bound to a mountpoint within the pseudo file system |
| and to a file system. At present, NuttX supports the standard VFAT |
| and ROMFS file systems, a special, wear-leveling NuttX FLASH File |
| System (NXFFS), as well as a Network File System client (NFS |
| version 3, UDP).</p> |
| <p><strong>Comparison to Linux</strong> From a programming perspective, the NuttX |
| file system appears very similar to a Linux file system. However, |
| there is a fundamental difference: The NuttX root file system is a |
| pseudo file system and true file systems may be mounted in the |
| pseudo file system. In the typical Linux installation by |
| comparison, the Linux root file system is a true file system and |
| pseudo file systems may be mounted in the true, root file system. |
| The approach selected by NuttX is intended to support greater |
| scalability from the very tiny platform to the moderate platform.</p> |
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