AXFS (Advanced XIP Filesystem) is a
compressed read-only file system
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...
for
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which ...
, initially developed at
Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
, and now maintained at
Numonyx
Numonyx was a semiconductor company making flash memories, which was founded on March 31, 2008, by Intel Corporation, STMicroelectronics and Francisco Partners. It was acquired by Micron Technology on February 9, 2010 for $1.27 billion USD.
...
. It was designed to use
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 ef ...
(XIP) alongside compression aiming to reduce
boot
A boot is a type of footwear. Most boots mainly cover the foot and the ankle, while some also cover some part of the lower calf. Some boots extend up the leg, sometimes as far as the knee or even the hip. Most boots have a heel that is cle ...
and program load times, while retaining a small
memory footprint
Memory footprint refers to the amount of main memory that a program uses or references while running.
The word footprint generally refers to the extent of physical dimensions that an object occupies, giving a sense of its size. In computing, the ...
for
embedded devices
An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' as ...
. This is achieved by mixing compressed and uncompressed
pages
Page most commonly refers to:
* Page (paper), one side of a leaf of paper, as in a book
Page, PAGE, pages, or paging may also refer to:
Roles
* Page (assistance occupation), a professional occupation
* Page (servant), traditionally a young mal ...
in the same executable file. AXFS is
free software
Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, no ...
(licensed under the
GPL
The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general u ...
).
Cramfs
The compressed ROM/RAM file system (or cramfs) is a free ( GPL'ed) read-only Linux file system designed for simplicity and space-efficiency. It is mainly used in embedded and small-footprint systems.
Unlike a compressed image of a conventional ...
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 also
*
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 al ...
is another read-only compressed file system
*
Cloop is a compressed
loopback device module for the
Linux kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ope ...
*
e2compr
The 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 design ...
provides compression for
ext2
The 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 pr ...
*
List of file systems
The following lists identify, characterize, and link to more thorough information on Computer 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 ...
*
Comparison of file systems
The following tables compare general and technical information for a number of file systems.
General information
Limits
Metadata
Features File capabilities
Block capabilities
Note that in addition to the below table, blo ...
References
Further reading
* Tony Benavides, Justin Treon, Jared Hulbert and Weide Chang,
The Enabling of an Execute-In-Place Architecture to Reduce the Embedded System Memory Footprint and Boot Time', Journal of Computers, Vol. 3, No. 1, Jan 2008, pp. 79–89
* Jared Hulbert,
Introducing the Advanced XIP File System',
talk Proceedings of the 2008
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. ...
External links
AXFS website* Justin Treon (February 14, 2008
Side by side comparison of launching applications stored in the AXFS, SquashFS, CRAMFS and JFFS2 read-only filing systems.(video)
"Application eXecute-In-Place (XIP) with Linux and AXFS"
Free special-purpose file systems
Compression file systems
Read-only file systems supported by the Linux kernel
{{Storage-software-stub