Changes between Version 6 and Version 7 of Developer/FileSystems


Ignore:
Timestamp:
Sep 12, 2008, 10:15:56 AM (11 years ago)
Author:
ChrisJohns
Comment:

Update the block file info at the start.

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  • Developer/FileSystems

    v6 v7  
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    9 RTEMS provides support for file systems. The POSIX standard and the Single Unix Specification define a range of calls that allow applications to access and control files on a file system. Embedded systems have evolved to allow support for file systems and files. Files are a well understood means of managing various forms of data on desktop and server type system. The same can also applies to embedded system with some obvious constraints.
     9RTEMS provides support for file systems. The POSIX standard and the Single Unix Specification define a range of calls that allow applications to access and control files on a file system. Embedded systems have evolved to allow support for file systems and files. Files are a well understood means of managing various forms of data on desktop and server type system and the same can also apply to embedded system with some obvious constraints.
    1010
    1111Embedded applications benefits of using files are:
     
    1818The downside is a larger embedded foot print for code and data, and file system accesses are typically not real-time.
    1919
    20 The code and data size depends on the file system being used. A simple TFTP type file system has a small foot print but does require a networking stack. A block device file system such as the FAT file system has the overhead of implementing a full file system.
     20The code and data size depends on the file system being used. A simple TFTP type file system has a small foot print but does require a networking stack. A block device file system such as the FAT file system has the overhead of implementing a full file system plus the cache.
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    2222Real-time use of a file system is a complex issue and beyond the scope of this topic. Dr Joel Sherrill's PHD thesis studied real-time file-systems and concluded the whole system from application to driver needs to be considered when handling real-time data. You should contract Joel if you would like advise on this topic. Typically an application would read configuration type data into memory rather than use the file-system directly.
     
    2929# FTP or File Transfer Protocol File System
    3030# NFS or Network File System
    31 # FAT or MSDOS File System
     31# FAT or MSDOS File System using the Block Device API.
    3232
    3333The root file system is always the IMFS file system. It provides a small footprint means to allow device driver nodes to be located in the file system, and to mount other file systems. There is also the MiniIMFS which is smaller in size with less features.
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     35RTEMS provides a block device API. Built onto the block device API is a cache. The MSDOS file system uses the cache and therefore the Block Device API. The block devices supported are:
     36
     37# ATA disks supporting IDE disk drives as well as Compact Flash disks configured in IDE mode
     38# RAM disk
     39# Non-volatile disk
     40# Flash disk
     41
     42See [wiki:Using_the_RTEMS_File_System Using the RTEMS File System] to see how to configure and use file systems in RTEMS.
    3443= IMFS File System =
    3544