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AXFS
AXFS (Advanced XIP Filesystem) is a compressed read-only file system for Linux, initially developed at Intel, and now maintained at Numonyx. It was designed to use execute in place (XIP) alongside compression aiming to reduce boot and program load times, while retaining a small memory footprint for embedded devices. This is achieved by mixing compressed and uncompressed pages in the same executable file. AXFS is free software licensed under the GPL. Cramfs is another read-only compressed file system that supports XIP (with patches); however, it uses a strategy of decompressing entire files, whereas AXFS supports XIP with page granularity.Justin Treon, (2008-05-09) ', LinuxDevices.com, "There are two XIP-enabled Linux filing systems that can be used for a Balanced XIP implementation: Linear XIP CRAMFS and AXFS. The Linear XIP CRAMFS decompresses files on a file-by-file basis, whereas AXFS decompresses files on a page-by-page basis offering more optimal Flash usage." See ...
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Execute In Place
In computer science, execute in place (XIP) is a method of executing programs directly from long-term storage rather than copying it into RAM. It is an extension of using shared memory to reduce the total amount of memory required. Its general effect is that the program text consumes no writable memory, saving it for dynamic data, and that all instances of the program are run from a single copy. For this to work, several criteria have to be met: * The storage must provide a similar interface to the CPU as regular memory (or an adaptive layer must be present). * This interface must provide sufficiently fast read operations with a random access pattern. * The file system, if one is used, needs to expose appropriate mapping functions. * The program must either be linked to be aware of the address the storage appears at in the system or be position-independent. * The program must not modify data within the loaded image. The storage requirements are usually met by using NOR fla ...
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List Of File Systems
The following lists identify, characterize, and link to more thorough information on file systems. Many older operating systems support only their one "native" file system, which does not bear any name apart from the name of the operating system itself. Disk file systems Disk file systems are usually block-oriented. Files in a block-oriented file system are sequences of blocks, often featuring fully random-access read, write, and modify operations. * ADFS – Acorn's Advanced Disc filing system, successor to DFS. * AdvFS – Advanced File System, designed by Digital Equipment Corporation for their Digital UNIX (now Tru64 UNIX) operating system. * APFS – Apple File System is a file system for Apple products. * AthFS – AtheOS File System, a 64-bit journaled filesystem now used by Syllable. Also called AFS. * BFS – the Boot File System used on System V release 4.0 and UnixWare. * BFS – the Be File System used on BeOS, occasionally misnamed as BeFS. Open source impl ...
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Data Compression
In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy. No information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information. Typically, a device that performs data compression is referred to as an encoder, and one that performs the reversal of the process (decompression) as a decoder. The process of reducing the size of a data file is often referred to as data compression. In the context of data transmission, it is called source coding: encoding is done at the source of the data before it is stored or transmitted. Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a sig ...
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Compressed File System
Compression may refer to: Physical science *Compression (physics), size reduction due to forces *Compression member, a structural element such as a column *Compressibility, susceptibility to compression *Gas compression *Compression ratio, of a combustion engine *Compression (geology) *Compression or compressive strength Information science *Bandwidth compression, reducing effort in data transmission *Data compression, reducing the data required for information **Audio compression (data), reducing the data required for audio **Compression artifact, defect in data due to compression **Image compression, of digital images **Video compression *One-way compression function, a cryptographic primitive Medicine * Brain compression, a medical condition *Compression bandage *Pressing on the lower abdominal area in an intravenous pyelogram *Cold compression therapy, for minor injuries Other *Amplifier gain compression, due to nonlinearity *Compression (dance), several techniques *Compress ...
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Free Special-purpose File Systems
Free may refer to: Concept * Freedom, the ability to act or change without constraint or restriction * Emancipate, attaining civil and political rights or equality * Free (''gratis''), free of charge * Gratis versus libre, the difference between the two common meanings of the adjective "free". Computing * Free (programming), a function that releases dynamically allocated memory for reuse * Free software, software usable and distributable with few restrictions and no payment *, an emoji in the Enclosed Alphanumeric Supplement block. Mathematics * Free object ** Free abelian group ** Free algebra ** Free group ** Free module ** Free semigroup * Free variable People * Free (surname) * Free (rapper) (born 1968), or Free Marie, American rapper and media personality * Free, a pseudonym for the activist and writer Abbie Hoffman * Free (active 2003–), American musician in the band FreeSol Arts and media Film and television * ''Free'' (film), a 2001 American d ...
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Linux Symposium
The Linux Symposium was a Linux and open source conference held annually in Canada from 1999 to 2014. The conference was initially named Ottawa Linux Symposium and was held only in Ottawa, but was renamed after being held in other cities in Canada. Even after the name change, however, it was still referred to as OLS. The conference featured 100+ paper presentations, tutorials, birds of a feather sessions and mini summits on a wide range of topics. There were 650 attendees from 20+ countries in 2008. History The 2009 Symposium was held in Montréal, Quebec. The 2011 and 2012 Symposium were both held in Ottawa. In 2014, OLS organizers put together an unsuccessful campaign on Indiegogo to raise funds in order to pay off debts from previous events.
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Comparison Of File Systems
The following tables compare general and technical information for a number of file systems. General information Metadata All widely used file systems record a last modified time stamp (also known as "mtime"). It is not included in the table. Individual file systems may record additional special types of date and time stamps. For example, the specification of ISO 9660 includes a "File Expiration Date and Time" and a "File Effective Date and Time". Features File capabilities Block capabilities Note that in addition to the below table, block capabilities can be implemented below the file system layer in Linux (Logical Volume Manager (Linux), LVM, , Dm-crypt#cryptsetup, cryptsetup) or Windows (Volume Shadow Copy Service, SECURITY.BIN, SECURITY), etc. Resize capabilities "Online" and "offline" are synonymous with "mounted" and "not mounted". Allocation and layout policies OS support Limits While storage devices usually have their size ex ...
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Ext2
ext2, or second extended file system, is a file system for the Linux kernel (operating system), kernel. It was initially designed by French software developer Rémy Card as a replacement for the extended file system (ext). Having been designed according to the same principles as the Berkeley Fast File System from Berkeley Software Distribution, BSD, it was the first commercial-grade filesystem for Linux. The canonical implementation of ext2 is the "ext2fs" filesystem driver in the Linux kernel. Other implementations (of varying quality and completeness) exist in GNU Hurd, MINIX 3, some BSD kernels, in MiNT, Haiku (operating system), Haiku and as third-party Microsoft Windows and macOS (via Filesystem_in_Userspace, FUSE) drivers. This driver was deprecated in Linux version 6.9 in favor of the ext4 driver, as the ext4 driver works with ext2 filesystems. ext2 was the default filesystem in several Linux distributions, including Debian and Red Hat Linux, until supplanted by ext3, w ...
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E2compr
ext2, or second extended file system, is a file system for the Linux kernel. It was initially designed by French software developer Rémy Card as a replacement for the extended file system (ext). Having been designed according to the same principles as the Berkeley Fast File System from BSD, it was the first commercial-grade filesystem for Linux. The canonical implementation of ext2 is the "ext2fs" filesystem driver in the Linux kernel. Other implementations (of varying quality and completeness) exist in GNU Hurd, MINIX 3, some BSD kernels, in MiNT, Haiku and as third-party Microsoft Windows and macOS (via FUSE) drivers. This driver was deprecated in Linux version 6.9 in favor of the ext4 driver, as the ext4 driver works with ext2 filesystems. ext2 was the default filesystem in several Linux distributions, including Debian and Red Hat Linux, until supplanted by ext3, which is almost completely compatible with ext2 and is a journaling file system. ext2 is still the filesyst ...
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Loop Device
In Unix-like operating systems, a loop device, vnd (vnode disk), or lofi (loop file interface) is a pseudo-device that makes a computer file accessible as a block device. Before use, a loop device must be connected to an existent file in the file system. The association provides the user with an application programming interface (API) that allows the file to be used in place of a block special file (cf. device file system). Thus, if the file contains an entire file system, the file may then be mounted as if it were a disk device. Files of this kind are often used for CD ISO images and floppy disk images. Mounting a file containing a file system via such a loop mount makes the files within that file system accessible. They appear in the mount point directory. A loop device may allow some kind of data elaboration during this redirection. For example, the device may be the unencrypted version of an encrypted file. In such a case, the file associated with a loop device may be anoth ...
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Cloop
The compressed loop device (cloop) is a module for the Linux kernel. It adds support for transparently decompressed, read-only block devices. It is not a compressed file system: cloop is mostly used as a convenient way to compress conventional file systems onto Live CDs. Cloop was originally written for the Levanta Bootable Business Card by Rusty Russell, but is now maintained by Klaus Knopper, the author of Knoppix. A compression ratio of about 2.5:1 is common for software. The Knoppix cloop image, for example, is 700 MB compressed and around 1.8 GB uncompressed. Design cloop images contain: * A shell script (with mount commands for the image) * A header with the number of blocks and the uncompressed block size * A seek index with compressed and uncompressed block sizes in pairs * zlib-compressed data blocks, packed end-to-end The data blocks are compressed separately; this makes it possible to seek to individual blocks without having to decompress the entire image f ...
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Squashfs
Squashfs is a compressed read-only file system for Linux. Squashfs compresses files, inodes and directories, and supports block sizes from 4 KiB up to 1 MiB for greater compression. Several compression algorithms are supported. Squashfs is also the name of free software, licensed under the GPL, for accessing Squashfs filesystems. Squashfs is intended for general read-only file-system use and in constrained block-device memory systems (e.g. embedded systems) where low overhead is needed. Uses Squashfs is used by the Live CD versions of Arch Linux, Clonezilla, Debian, Fedora, Gentoo Linux, KDE neon, Kali Linux, Linux Mint, NixOS, Salix, Ubuntu, openSUSE and on embedded distributions such as the OpenWrt and DD-WRT router firmware. It is also used in Chromecast, in Tiny Core Linux fopackaging extensions and for the system partitions of some Android releases ( Android Nougat). It is often combined with a union mount filesystem, such as UnionFS, OverlayFS, o ...
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