| ================= |
| NuttX File System |
| ================= |
| |
| **Overview**. 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. |
| |
| **Pseudo Root File System**. A simple *in-memory*, *pseudo* file |
| system can be enabled by default. This is an *in-memory* 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 *pseudo* file system (in the same sense that the Linux |
| ``/proc`` file system is also referred to as a pseudo file |
| system). |
| |
| Any user supplied data or logic can be accessed via the |
| pseudo-file system. Built in support is provided for character and |
| block `drivers <#DeviceDrivers>`__ in the ``/dev`` pseudo file |
| system directory. |
| |
| **Mounted File Systems** 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 ``mount()`` 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). |
| |
| **Comparison to Linux** 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. |
| |
