From c0a70dba6154f605226b2e1f763875f8d00f9a7b Mon Sep 17 00:00:00 2001 From: Sebastian Huber Date: Mon, 9 Mar 2020 08:51:47 +0100 Subject: c-user: Move "Filesystem Configuration" Update #3836. --- c-user/config/filesystem.rst | 547 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 547 insertions(+) create mode 100644 c-user/config/filesystem.rst (limited to 'c-user/config/filesystem.rst') diff --git a/c-user/config/filesystem.rst b/c-user/config/filesystem.rst new file mode 100644 index 0000000..063a8c3 --- /dev/null +++ b/c-user/config/filesystem.rst @@ -0,0 +1,547 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 1988, 2008 On-Line Applications Research Corporation (OAR) + +Filesystem Configuration +======================== + +By default, the In-Memory Filesystem (IMFS) is used as the base filesystem (also +known as root filesystem). In order to save some memory for your application, +you can disable the filesystem support with the +:ref:`CONFIGURE_APPLICATION_DISABLE_FILESYSTEM` configuration option. +Alternatively, you can strip down the features of the base filesystem with the +:ref:`CONFIGURE_USE_MINIIMFS_AS_BASE_FILESYSTEM` and +:ref:`CONFIGURE_USE_DEVFS_AS_BASE_FILESYSTEM` configuration options. These +three configuration options are mutually exclusive. They are intended for an +advanced application configuration. + +Features of the IMFS can be disabled and enabled with the following +configuration options: + +* :ref:`CONFIGURE_IMFS_DISABLE_CHMOD` + +* :ref:`CONFIGURE_IMFS_DISABLE_CHOWN` + +* :ref:`CONFIGURE_IMFS_DISABLE_LINK` + +* :ref:`CONFIGURE_IMFS_DISABLE_MKNOD` + +* :ref:`CONFIGURE_IMFS_DISABLE_MKNOD_FILE` + +* :ref:`CONFIGURE_IMFS_DISABLE_MOUNT` + +* :ref:`CONFIGURE_IMFS_DISABLE_READDIR` + +* :ref:`CONFIGURE_IMFS_DISABLE_READLINK` + +* :ref:`CONFIGURE_IMFS_DISABLE_RENAME` + +* :ref:`CONFIGURE_IMFS_DISABLE_RMNOD` + +* :ref:`CONFIGURE_IMFS_DISABLE_SYMLINK` + +* :ref:`CONFIGURE_IMFS_DISABLE_UNMOUNT` + +* :ref:`CONFIGURE_IMFS_DISABLE_UTIME` + +* :ref:`CONFIGURE_IMFS_ENABLE_MKFIFO` + +.. index:: CONFIGURE_APPLICATION_DISABLE_FILESYSTEM + +.. _CONFIGURE_APPLICATION_DISABLE_FILESYSTEM: + +CONFIGURE_APPLICATION_DISABLE_FILESYSTEM +---------------------------------------- + +CONSTANT: + ``CONFIGURE_APPLICATION_DISABLE_FILESYSTEM`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. If no other root file system configuration + parameters are specified, the IMFS will be used as the root file system. + +DESCRIPTION: + This configuration parameter is defined if the application dose not intend + to use any kind of filesystem support. This include the device + infrastructure necessary to support ``printf()``. + +NOTES: + None. + +.. index:: CONFIGURE_IMFS_ENABLE_MKFIFO + +.. _CONFIGURE_IMFS_ENABLE_MKFIFO: + +CONFIGURE_IMFS_ENABLE_MKFIFO +---------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_ENABLE_MKFIFO`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to make FIFOs + is enabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_CHMOD + +.. _CONFIGURE_IMFS_DISABLE_CHMOD: + +CONFIGURE_IMFS_DISABLE_CHMOD +---------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_CHMOD`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to change + the mode is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_CHOWN + +.. _CONFIGURE_IMFS_DISABLE_CHOWN: + +CONFIGURE_IMFS_DISABLE_CHOWN +---------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_CHOWN`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to change + the owner is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_LINK + +.. _CONFIGURE_IMFS_DISABLE_LINK: + +CONFIGURE_IMFS_DISABLE_LINK +--------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_LINK`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to create + hard links is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_MKNOD + +.. _CONFIGURE_IMFS_DISABLE_MKNOD: + +CONFIGURE_IMFS_DISABLE_MKNOD +---------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_MKNOD`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to make + directories, devices, regular files and FIFOs is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_MKNOD_FILE + +.. _CONFIGURE_IMFS_DISABLE_MKNOD_FILE: + +CONFIGURE_IMFS_DISABLE_MKNOD_FILE +--------------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_MKNOD_FILE`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to make + regular files is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_MOUNT + +.. _CONFIGURE_IMFS_DISABLE_MOUNT: + +CONFIGURE_IMFS_DISABLE_MOUNT +---------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_MOUNT`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to mount + other file systems is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_READDIR + +.. _CONFIGURE_IMFS_DISABLE_READDIR: + +CONFIGURE_IMFS_DISABLE_READDIR +------------------------------ + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_READDIR`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to read a + directory is disabled in the root IMFS. It is still possible to open nodes + in a directory. + +.. index:: CONFIGURE_IMFS_DISABLE_READLINK + +.. _CONFIGURE_IMFS_DISABLE_READLINK: + +CONFIGURE_IMFS_DISABLE_READLINK +------------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_READLINK`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to read + symbolic links is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_RENAME + +.. _CONFIGURE_IMFS_DISABLE_RENAME: + +CONFIGURE_IMFS_DISABLE_RENAME +----------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_RENAME`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to rename + nodes is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_RMNOD + +.. _CONFIGURE_IMFS_DISABLE_RMNOD: + +CONFIGURE_IMFS_DISABLE_RMNOD +---------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_RMNOD`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to remove + nodes is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_SYMLINK + +.. _CONFIGURE_IMFS_DISABLE_SYMLINK: + +CONFIGURE_IMFS_DISABLE_SYMLINK +------------------------------ + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_SYMLINK`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to create + symbolic links is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_UNMOUNT + +.. _CONFIGURE_IMFS_DISABLE_UNMOUNT: + +CONFIGURE_IMFS_DISABLE_UNMOUNT +------------------------------ + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_UNMOUNT`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to unmount + file systems is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_DISABLE_UTIME + +.. _CONFIGURE_IMFS_DISABLE_UTIME: + +CONFIGURE_IMFS_DISABLE_UTIME +---------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_DISABLE_UTIME`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the support to change + times is disabled in the root IMFS. + +.. index:: CONFIGURE_IMFS_MEMFILE_BYTES_PER_BLOCK + +.. _CONFIGURE_IMFS_MEMFILE_BYTES_PER_BLOCK: + +CONFIGURE_IMFS_MEMFILE_BYTES_PER_BLOCK +-------------------------------------- + +CONSTANT: + ``CONFIGURE_IMFS_MEMFILE_BYTES_PER_BLOCK`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Valid values for this configuration parameter are a power of two (2) + between 16 and 512 inclusive. In other words, valid values are 16, 32, 64, + 128, 256,and 512. + +DEFAULT VALUE: + The default IMFS block size is 128 bytes. + +DESCRIPTION: + This configuration parameter specifies the block size for in-memory files + managed by the IMFS. The configured block size has two impacts. The first + is the average amount of unused memory in the last block of each file. For + example, when the block size is 512, on average one-half of the last block + of each file will remain unused and the memory is wasted. In contrast, when + the block size is 16, the average unused memory per file is only 8 + bytes. However, it requires more allocations for the same size file and + thus more overhead per block for the dynamic memory management. + + Second, the block size has an impact on the maximum size file that can be + stored in the IMFS. With smaller block size, the maximum file size is + correspondingly smaller. The following shows the maximum file size possible + based on the configured block size: + + - when the block size is 16 bytes, the maximum file size is 1,328 bytes. + + - when the block size is 32 bytes, the maximum file size is 18,656 bytes. + + - when the block size is 64 bytes, the maximum file size is 279,488 bytes. + + - when the block size is 128 bytes, the maximum file size is 4,329,344 bytes. + + - when the block size is 256 bytes, the maximum file size is 68,173,568 bytes. + + - when the block size is 512 bytes, the maximum file size is 1,082,195,456 + bytes. + +.. index:: CONFIGURE_MAXIMUM_DEVICES + +.. _CONFIGURE_MAXIMUM_DEVICES: + +CONFIGURE_MAXIMUM_DEVICES +------------------------- + +CONSTANT: + ``CONFIGURE_MAXIMUM_DEVICES`` + +DATA TYPE: + Unsigned integer (``uint32_t``). + +RANGE: + Positive. + +DEFAULT VALUE: + If ``BSP_MAXIMUM_DEVICES`` is defined, then the default value is + ``BSP_MAXIMUM_DEVICES``, otherwise the default value is 4. + +DESCRIPTION: + ``CONFIGURE_MAXIMUM_DEVICES`` is defined to the number of individual + devices that may be registered in the device file system (devFS). + +NOTES: + This option is specific to the device file system (devFS) and should not be + confused with the ``CONFIGURE_MAXIMUM_DRIVERS`` option. This parameter + only impacts the devFS and thus is only used by ```` when + ``CONFIGURE_USE_DEVFS_AS_BASE_FILESYSTEM`` is specified. + +.. index:: CONFIGURE_USE_DEVFS_AS_BASE_FILESYSTEM + +.. _CONFIGURE_USE_DEVFS_AS_BASE_FILESYSTEM: + +CONFIGURE_USE_DEVFS_AS_BASE_FILESYSTEM +-------------------------------------- + +CONSTANT: + ``CONFIGURE_USE_DEVFS_AS_BASE_FILESYSTEM`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. If no other root file system configuration + parameters are specified, the IMFS will be used as the root file system. + +DESCRIPTION: + This configuration parameter is defined if the application wishes to use + the device-only filesytem as the root file system. + +NOTES: + The device-only filesystem supports only device nodes and is smaller in + executable code size than the full IMFS and miniIMFS. + + The devFS is comparable in functionality to the pseudo-filesystem name + space provided before RTEMS release 4.5.0. + +.. index:: CONFIGURE_USE_MINIIMFS_AS_BASE_FILESYSTEM + +.. _CONFIGURE_USE_MINIIMFS_AS_BASE_FILESYSTEM: + +CONFIGURE_USE_MINIIMFS_AS_BASE_FILESYSTEM +----------------------------------------- + +CONSTANT: + ``CONFIGURE_USE_MINIIMFS_AS_BASE_FILESYSTEM`` + +DATA TYPE: + Boolean feature macro. + +RANGE: + Defined or undefined. + +DEFAULT VALUE: + This is not defined by default. + +DESCRIPTION: + In case this configuration option is defined, then the following + configuration options will be defined as well + + - ``CONFIGURE_IMFS_DISABLE_CHMOD``, + + - ``CONFIGURE_IMFS_DISABLE_CHOWN``, + + - ``CONFIGURE_IMFS_DISABLE_UTIME``, + + - ``CONFIGURE_IMFS_DISABLE_LINK``, + + - ``CONFIGURE_IMFS_DISABLE_SYMLINK``, + + - ``CONFIGURE_IMFS_DISABLE_READLINK``, + + - ``CONFIGURE_IMFS_DISABLE_RENAME``, and + + - ``CONFIGURE_IMFS_DISABLE_UNMOUNT``. -- cgit v1.2.3