@c
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@c
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@c COPYRIGHT (c) 1988-2002.
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@c COPYRIGHT (c) 1988-2002.
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@c On-Line Applications Research Corporation (OAR).
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@c On-Line Applications Research Corporation (OAR).
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@c All rights reserved.
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@c All rights reserved.
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@c
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@c
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@c init.t,v 1.8 2002/01/17 21:47:45 joel Exp
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@c init.t,v 1.8 2002/01/17 21:47:45 joel Exp
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@c
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@c
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@chapter System Initialization
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@chapter System Initialization
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After the RTEMS initialization is performed, the application's
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After the RTEMS initialization is performed, the application's
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initialization will be performed. Part of initialization is a call to
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initialization will be performed. Part of initialization is a call to
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rtems_filesystem_initialize(). This routine will mount the `In Memory File
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rtems_filesystem_initialize(). This routine will mount the `In Memory File
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System' as the base filesystem. Mounting the base filesystem consists
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System' as the base filesystem. Mounting the base filesystem consists
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of the following:
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of the following:
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@itemize @bullet
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@itemize @bullet
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@item Initialization of mount table chain control structure
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@item Initialization of mount table chain control structure
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@item Allocation of a @code{jnode} structure that will server as the root node
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@item Allocation of a @code{jnode} structure that will server as the root node
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of the `In Memory Filesystem'
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of the `In Memory Filesystem'
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@item Initialization of the allocated @code{jnode} with the appropriate OPS,
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@item Initialization of the allocated @code{jnode} with the appropriate OPS,
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directory handlers and pathconf limits and options.
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directory handlers and pathconf limits and options.
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@item Allocation of a memory region for filesystem specific global
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@item Allocation of a memory region for filesystem specific global
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management variables
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management variables
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@item Creation of first mount table entry for the base filesystem
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@item Creation of first mount table entry for the base filesystem
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@item Initialization of the first mount table chain entry to indicate that
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@item Initialization of the first mount table chain entry to indicate that
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the mount point is NULL and the mounted filesystem is the base file
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the mount point is NULL and the mounted filesystem is the base file
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system
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system
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@end itemize
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@end itemize
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After the base filesystem has been mounted, the following operations are
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After the base filesystem has been mounted, the following operations are
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performed under its directory structure:
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performed under its directory structure:
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@itemize @bullet
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@itemize @bullet
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@item Creation of the /dev directory
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@item Creation of the /dev directory
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@item Registration of devices under /dev directory
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@item Registration of devices under /dev directory
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@end itemize
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@end itemize
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@section Base Filesystem
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@section Base Filesystem
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RTEMS initially mounts a RAM based file system known as the base file system.
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RTEMS initially mounts a RAM based file system known as the base file system.
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The root directory of this file system tree serves as the logical root of the
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The root directory of this file system tree serves as the logical root of the
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directory hierarchy (Figure 3). Under the root directory a `/dev' directory
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directory hierarchy (Figure 3). Under the root directory a `/dev' directory
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is created under which all I/O device directories and files are registered as
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is created under which all I/O device directories and files are registered as
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part of the file system hierarchy.
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part of the file system hierarchy.
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@example
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@example
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Figure of the tree structure goes here.
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Figure of the tree structure goes here.
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@end example
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@end example
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A RAM based file system draws its management resources from memory. File and
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A RAM based file system draws its management resources from memory. File and
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directory nodes are simply allocated blocks of memory. Data associated with
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directory nodes are simply allocated blocks of memory. Data associated with
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regular files is stored in collections of memory blocks. When the system is
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regular files is stored in collections of memory blocks. When the system is
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turned off or restarted all memory-based components of the file system are
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turned off or restarted all memory-based components of the file system are
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lost.
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lost.
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The base file system serves as a starting point for the mounting of file
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The base file system serves as a starting point for the mounting of file
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systems that are resident on semi-permanent storage media. Examples of such
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systems that are resident on semi-permanent storage media. Examples of such
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media include non- volatile memory, flash memory and IDE hard disk drives
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media include non- volatile memory, flash memory and IDE hard disk drives
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(Figure 3). File systems of other types will be mounted onto mount points
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(Figure 3). File systems of other types will be mounted onto mount points
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within the base file system or other file systems that are subordinate to the
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within the base file system or other file systems that are subordinate to the
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base file system. The framework set up under the base file system will allow
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base file system. The framework set up under the base file system will allow
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for these new file system types and the unique data and functionality that is
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for these new file system types and the unique data and functionality that is
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required to manage the future file systems.
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required to manage the future file systems.
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@subsection Base Filesystem Mounting
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@subsection Base Filesystem Mounting
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At present, the first file system to be mounted is the `In Memory File
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At present, the first file system to be mounted is the `In Memory File
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System'. It is mounted using a standard MOUNT() command in which the mount
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System'. It is mounted using a standard MOUNT() command in which the mount
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point is NULL. This flags the mount as the first file system to be
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point is NULL. This flags the mount as the first file system to be
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registered under the operating system and appropriate initialization of file
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registered under the operating system and appropriate initialization of file
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system management information is performed (See figures 4 and 5). If a
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system management information is performed (See figures 4 and 5). If a
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different file system type is desired as the base file system, alterations
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different file system type is desired as the base file system, alterations
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must be made to base_fs.c. This routine handles the mount of the base file
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must be made to base_fs.c. This routine handles the mount of the base file
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system.
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system.
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@example
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@example
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Figure of the mount table chain goes here.
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Figure of the mount table chain goes here.
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@end example
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@end example
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Once the root of the base file system has been established and it has been
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Once the root of the base file system has been established and it has been
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recorded as the mount point of the base file system, devices are integrated
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recorded as the mount point of the base file system, devices are integrated
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into the base file system. For every device that is configured into the
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into the base file system. For every device that is configured into the
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system (See ioman.c) a device registration process is performed. Device
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system (See ioman.c) a device registration process is performed. Device
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registration produces a unique dev_t handle that consists of a major and
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registration produces a unique dev_t handle that consists of a major and
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minor device number. In addition, the configuration information for each
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minor device number. In addition, the configuration information for each
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device contains a text string that represents the fully qualified pathname to
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device contains a text string that represents the fully qualified pathname to
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that device's place in the base file system's hierarchy. A file system node
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that device's place in the base file system's hierarchy. A file system node
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is created for the device along the specified registration path.
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is created for the device along the specified registration path.
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@example
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@example
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Figure of the Mount Table Processing goes here.
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Figure of the Mount Table Processing goes here.
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@end example
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@end example
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Note: Other file systems can be mounted but they are mounted onto points
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Note: Other file systems can be mounted but they are mounted onto points
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(directory mount points) in the base file system.
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(directory mount points) in the base file system.
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