SquashFS: Difference between revisions

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The Live CD versions of various Linux distributions mount SquashFS as the root filesystem and mostly use [[OverlayFS]] to provide a writable layer over SquashFS.  
The Live CD versions of various Linux distributions mount SquashFS as the root filesystem and mostly use [[OverlayFS]] to provide a writable layer over SquashFS.  


In Alpine Linux [[Diskless Mode]], the read-only squashfs image named '''modloop''' serves as the lower layer. The modloop contains kernel modules and essential system files. The modloop gets mounted as a loop device at /.modloop. The unpacked [[Diskless Mode#Apkovl|Apkovl]] content is loaded and mounted as its root filesystem into tmpfs, thus making it fully writable in RAM.  
In Alpine Linux, the '''modloop''' file is a squashfs image. The modloop contains kernel modules and essential firmware files. During bootup, the modloop gets mounted in read only mode as a loop device at /.modloop.  


== See also ==
== See also ==


* [[How to make a custom ISO image with mkimage]]
* [https://github.com/plougher/squashfs-tools squashfs-tools repository]
* [https://github.com/plougher/squashfs-tools squashfs-tools repository]
* [https://wiki.gentoo.org/wiki/SquashFS Gentoo wiki]
* [https://wiki.gentoo.org/wiki/SquashFS Gentoo wiki]
[[Category:Filesystems]]
[[Category:Filesystems]]

Latest revision as of 05:01, 2 April 2025

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.

The Live CD versions of various Linux distributions mount SquashFS as the root filesystem and mostly use OverlayFS to provide a writable layer over SquashFS.

In Alpine Linux, the modloop file is a squashfs image. The modloop contains kernel modules and essential firmware files. During bootup, the modloop gets mounted in read only mode as a loop device at /.modloop.

See also