SherbyNet - /page/wikibook/entry.mu

Micron Document

<!DOCTYPE html>

<title>Initial ramdisk</title>

</head>

<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Initial ramdisk</span></span>

</h1>

</header>

<p>

In <a href="Linux" title="Linux">Linux</a> systems, <b><code>initrd</code></b> (<i>initial <a href="Ramdisk" class="mw-redirect" title="Ramdisk">ramdisk</a></i>) is a scheme for loading a temporary root <a href="File_system" title="File system">file system</a> into <a href="Computer_memory" title="Computer memory">memory</a>, to be used as part of the <a href="Linux_startup_process" class="mw-redirect" title="Linux startup process">Linux startup process</a>. <code>initrd</code> and <code>initramfs</code> (from <b>INIT</b>ial <b>RAM</b> <b>F</b>ile <b>S</b>ystem) refer to two different methods of achieving this. Both are commonly used to make preparations before the real <a href="Root_directory" title="Root directory">root</a> file system can be <a href="Mount_(Unix)" title="Mount (Unix)">mounted</a>.

</p>

<div class="mw-heading mw-heading2"><h2 id="Rationale">Rationale</h2></div>

<p>Many <a href="Linux_distribution" title="Linux distribution">Linux distributions</a> ship a single, generic <a href="Linux_kernel" title="Linux kernel">Linux kernel</a> image –one which the distribution's developers create specifically to boot on a wide variety of hardware. The <a href="Device_driver" title="Device driver">device drivers</a> for this generic kernel image are included as <a href="Loadable_kernel_module" title="Loadable kernel module">loadable kernel modules</a> because statically compiling many drivers into one kernel causes the kernel image to be much larger, perhaps too large to boot on computers with limited memory, or in some cases to cause boot-time crashes or other problems due to probing for nonexistent or conflicting hardware. This static-compiled kernel approach also leaves modules in kernel memory which are no longer used or needed, and raises the problem of detecting and loading the modules necessary to mount the root file system at boot time, or for that matter, deducing where or what the root file system is.<sup id="cite_ref-almesberger2_1-0" class="reference"><a href="#cite_note-almesberger2-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>

</p><p>To further complicate matters, the root file system may be on a software <a href="RAID" title="RAID">RAID</a> volume, <a href="Logical_Volume_Manager_(Linux)" title="Logical Volume Manager (Linux)">LVM</a>, <a href="Network_File_System_(protocol)" class="mw-redirect" title="Network File System (protocol)">NFS</a> (on diskless workstations), or on an encrypted partition. All of these require special preparations to mount.<sup id="cite_ref-landley2_2-0" class="reference"><a href="#cite_note-landley2-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p><p>Another complication is kernel support for <a href="Hibernate_(OS_feature)" class="mw-redirect" title="Hibernate (OS feature)">hibernation</a>, which suspends the computer to disk by dumping an image of the entire contents of memory to a <a href="Swap_partition" class="mw-redirect" title="Swap partition">swap partition</a> or a regular file, then powering off. On next boot, this image has to be made accessible before it can be loaded back into memory.

</p><p>To avoid having to hardcode handling for so many special cases into the kernel, an initial boot stage with a temporary root file-system—now dubbed <a href="Early_user_space" class="mw-redirect" title="Early user space">early user space</a>—is used. This root file-system can contain user-space helpers which perform the hardware detection, module loading and device discovery necessary to mount the actual file-system.<sup id="cite_ref-landley2_2-1" class="reference"><a href="#cite_note-landley2-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading2"><h2 id="Implementation">Implementation</h2></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .hatnote{font-style:italic}.mw-parser-output div.hatnote{padding-left:1.6em;margin-bottom:0.5em}.mw-parser-output .hatnote i{font-style:normal}.mw-parser-output .hatnote+link+.hatnote{margin-top:-0.5em}@media print{body.ns-0 .mw-parser-output .hatnote{display:none!important}}

/* end https://en.wikipedia.org/ */

</style><div role="note" class="hatnote navigation-not-searchable">See also: <a href="Booting" title="Booting">Booting</a></div>

<div role="note" class="hatnote navigation-not-searchable">See also: <a href="Linux_startup_process" class="mw-redirect" title="Linux startup process">Linux startup process</a></div>

<p>An <a href="Disk_image" title="Disk image">image</a> of this initial root file system (along with the kernel image) must be stored somewhere accessible by the Linux <a href="Bootloader" title="Bootloader">bootloader</a> or the boot firmware of the computer. This can be the root file system itself, a <a href="El_Torito_(CD-ROM_standard)" class="mw-redirect" title="El Torito (CD-ROM standard)">boot image</a> on an <a href="Optical_disc" title="Optical disc">optical disc</a>, a small partition on a local disk (a <i>boot partition</i>, usually using <a href="Ext2" title="Ext2">ext2</a> or <a href="File_Allocation_Table" title="File Allocation Table">FAT</a> file systems), or a <a href="Trivial_File_Transfer_Protocol" title="Trivial File Transfer Protocol">TFTP</a> server (on systems that can boot from <a href="Ethernet" title="Ethernet">Ethernet</a>).

</p><p>The bootloader will load the kernel and initial root file system image into memory and then start the kernel, passing in the memory address of the image. At the end of its boot sequence, the kernel tries to determine the format of the image from its first few blocks of data, which can lead either to the initrd or initramfs scheme.

</p><p>In the <b>initrd</b> scheme, the image may be a file system image (optionally compressed), which is made available in a special <a href="Block_device" class="mw-redirect" title="Block device">block device</a> (<style data-mw-deduplicate="TemplateStyles:r886049734">

/* start https://en.wikipedia.org/ */

.mw-parser-output .monospaced{font-family:monospace,monospace}

/* end https://en.wikipedia.org/ */

</style><span class="monospaced">/dev/ram</span>) that is then mounted as the initial root file system.<sup id="cite_ref-almesberger_3-0" class="reference"><a href="#cite_note-almesberger-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> The driver for that file system must be compiled statically into the kernel. Many distributions originally used compressed <a href="Ext2" title="Ext2">ext2</a> file system images, while the others (including <a href="Debian" title="Debian">Debian</a> 3.1) used <a href="Cramfs" title="Cramfs">cramfs</a> in order to boot on memory-limited systems, since the cramfs image can be mounted in-place without requiring extra space for decompression. Once the initial root file system is up, the kernel executes <span class="monospaced">/linuxrc</span> as its first process;<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> when it exits, the kernel assumes that the real root file system has been mounted and executes <span class="monospaced">/sbin/init</span> to begin the normal user-space boot process.<sup id="cite_ref-almesberger_3-1" class="reference"><a href="#cite_note-almesberger-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup>

</p><p>In the <b>initramfs</b> scheme (available since the Linux kernel 2.6.13), the image may be a <a href="Cpio" title="Cpio">cpio</a> archive (optionally compressed) or a concatenation of such archives. The archive is unpacked by the kernel into a special instance of a <a href="Tmpfs" title="Tmpfs">tmpfs</a> that becomes the initial root file system. This scheme has the advantage of not requiring an intermediate file system or block drivers to be compiled into the kernel.<sup id="cite_ref-landley_5-0" class="reference"><a href="#cite_note-landley-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> Some systems use the <a href="Dracut_(initramfs)" class="mw-redirect" title="Dracut (initramfs)">dracut</a> package to create an initramfs image.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> In the initramfs scheme, the kernel executes <span class="monospaced">/init</span> as its first process that is not expected to exit.<sup id="cite_ref-landley_5-1" class="reference"><a href="#cite_note-landley-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> For some applications, initramfs can use the <b>casper</b> utility to create a writable environment using <a href="Unionfs" class="mw-redirect" title="Unionfs">unionfs</a> to overlay a <a href="Persistence_layer" class="mw-redirect" title="Persistence layer">persistence layer</a> over a read-only root filesystem image. For example, overlay data can be stored on a <a href="USB_flash_drive" title="USB flash drive">USB flash drive</a>, while a compressed <a href="SquashFS" title="SquashFS">SquashFS</a> read-only image stored on a <a href="Live_CD" title="Live CD">live CD</a> acts as a root filesystem.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup>

</p><p>Depending on which algorithms were compiled statically into it, the kernel can unpack initrd/initramfs images compressed with <a href="Gzip" title="Gzip">gzip</a>, <a href="Bzip2" title="Bzip2">bzip2</a>, <a href="LZMA" title="LZMA">LZMA</a>, <a href="XZ_Utils" title="XZ Utils">XZ</a>, <a href="Lempel%E2%80%93Ziv%E2%80%93Oberhumer" title="Lempel–Ziv–Oberhumer">LZO</a>, <a href="LZ4_(compression_algorithm)" title="LZ4 (compression algorithm)">LZ4</a>,<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> and <a href="Zstandard" class="mw-redirect" title="Zstandard">zstd</a>.

</p>

<div class="mw-heading mw-heading3"><h3 id="Mount_preparations">Mount preparations</h3></div>

<p>Some Linux distributions such as <a href="Debian" title="Debian">Debian</a> will generate a customized initrd image which contains only whatever is necessary to boot some particular computer, such as <a href="Advanced_Technology_Attachment" class="mw-redirect" title="Advanced Technology Attachment">ATA</a>, <a href="SCSI" title="SCSI">SCSI</a> and filesystem <a href="Loadable_kernel_module" title="Loadable kernel module">kernel modules</a>. These typically embed the location and type of the root file system.

</p><p>Other Linux distributions (such as <a href="Fedora_(operating_system)" class="mw-redirect" title="Fedora (operating system)">Fedora</a> and <a href="Ubuntu_(operating_system)" class="mw-redirect" title="Ubuntu (operating system)">Ubuntu</a>) generate a more generic initrd image. These start only with the device name of the root file system (or its <a href="Universally_unique_identifier" title="Universally unique identifier">UUID</a>) and must discover everything else at boot time. In this case, the software must perform a complex cascade of tasks to get the root file system mounted:

</p>

<ul><li>Any hardware drivers that the boot process depends on must be loaded. A common arrangement is to pack kernel modules for common storage devices onto the initrd and then invoke a <a href="Hotplug" class="mw-redirect" title="Hotplug">hotplug</a> agent to pull in modules matching the computer's detected hardware.</li>

<li>On systems which display a <a href="Bootsplash" title="Bootsplash">boot splash screen</a>, the video hardware must be initialized and a user-space helper started to paint animations onto the display in lockstep with the boot process.</li>

<li>If the root file system is on NFS, it must then bring up the primary <a href="Network_card" class="mw-redirect" title="Network card">network interface</a>, invoke a <a href="Dynamic_Host_Configuration_Protocol" title="Dynamic Host Configuration Protocol">DHCP</a> client, with which it can obtain a DHCP lease, extract the name of the NFS share and the address of the NFS server from the lease, and mount the NFS share.</li>

<li>If the root file system appears to be on a software RAID device, there is no way of knowing which devices the RAID volume spans; the standard <a href="Mdadm" title="Mdadm">MD utilities</a> must be invoked to scan all available block devices and bring the required ones online.</li>

<li>If the root file system appears to be on a <a href="Logical_volume" class="mw-redirect" title="Logical volume">logical volume</a>, the LVM utilities must be invoked to scan for and activate the <a href="Volume_group" class="mw-redirect" title="Volume group">volume group</a> containing it.</li>

<li>If the root file system is on an encrypted block device, the software needs to invoke a helper script to prompt the user to type in a passphrase and/or insert a hardware token (such as a <a href="Smart_card" title="Smart card">smart card</a> or a USB security <a href="Dongle" title="Dongle">dongle</a>), and then create a decryption target with the <a href="Device_mapper" title="Device mapper">device mapper</a>.</li></ul>

<p>Some distributions use an <a href="Event-driven_architecture" title="Event-driven architecture">event-driven</a> hotplug agent such as <a href="Udev" title="Udev">udev</a>, which invokes helper programs as hardware devices, disk partitions and storage volumes matching certain rules come online. This allows discovery to run in parallel, and to progressively cascade into arbitrary nestings of LVM, RAID or encryption to get at the root file system.

</p><p>When the root file system finally becomes visible, any maintenance tasks that cannot run on a mounted root file system are done, the root file system is mounted read-only, and any processes that must continue running (such as the splash screen helper and its command <a href="Named_pipe" title="Named pipe">FIFO</a>) are hoisted into the newly mounted root file system.

</p><p>The final root file system cannot simply be mounted over <span class="monospaced">/</span>, since that would make the scripts and tools on the initial root file system inaccessible for any final cleanup tasks:

</p>

<ul><li>On an initrd, the new root is mounted at a temporary mount point and rotated into place with <a rel="nofollow" class="external text" href="http://linux.die.net/man/8/pivot_root">pivot_root(8)</a> (which was introduced specifically for this purpose). This leaves the initial root file system at a mount point (such as <span class="monospaced">/initrd</span>) where normal boot scripts can later unmount it to free up memory held by the initrd.</li>

<li>On an initramfs, the initial root file system cannot be rotated away.<sup id="cite_ref-10" class="reference"><a href="#cite_note-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup> Instead, it is simply emptied and the final root file system mounted over the top.</li></ul>

<p>Most initial root file systems implement <span class="monospaced">/linuxrc</span> or <span class="monospaced">/init</span> as a shell script and thus include a minimal shell (usually <a href="Almquist_shell" title="Almquist shell">/bin/ash</a>) along with some essential user-space utilities (usually the <a href="BusyBox" title="BusyBox">BusyBox</a> toolkit). To further save space, the shell, utilities and their supporting libraries are typically compiled with space optimizations enabled (such as with <a href="GNU_Compiler_Collection" title="GNU Compiler Collection">gcc</a>'s "-Os" flag) and linked against <a href="Klibc" title="Klibc">klibc</a>, a minimal version of the <a href="C_standard_library" title="C standard library">C library</a> written specifically for this purpose.<sup id="cite_ref-11" class="reference"><a href="#cite_note-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup>

</p>

<div class="mw-heading mw-heading3"><h3 id="Other_uses">Other uses</h3></div>

<p>Installers for Linux distributions typically run entirely from an initramfs, as they must be able to host the installer interface and supporting tools before any persistent storage has been set up.

</p><p><a href="Tiny_Core_Linux" title="Tiny Core Linux">Tiny Core Linux</a><sup id="cite_ref-12" class="reference"><a href="#cite_note-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup> and <a href="Puppy_Linux" title="Puppy Linux">Puppy Linux</a><sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> can run entirely from initrd.

</p>

<div class="mw-heading mw-heading3"><h3 id="Similarities_in_other_operating_systems">Similarities in other operating systems</h3></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}

/* end https://en.wikipedia.org/ */

</style>

<p>Since Windows Vista,<sup id="cite_ref-14" class="reference"><a href="#cite_note-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup> Windows can boot from a <a href="Windows_Imaging_Format" title="Windows Imaging Format">WIM</a> disk image file, for which the file format is published;<sup id="cite_ref-15" class="reference"><a href="#cite_note-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> it is similar to the ZIP format except that it supports hard links, deduplicated chunks, and uses chunk-by-chunk compression. In this case, the whole WIM is initially loaded into RAM, followed by the kernel initialisation. Next, the loaded WIM is available as a SystemRoot with an assigned drive letter. The Windows installer uses this so it boots from BOOT.WIM, and then uses INSTALL.WIM as the collection of the Windows files to be installed.

</p><p>Also, <a href="Windows_Preinstallation_Environment" title="Windows Preinstallation Environment">Windows Preinstallation Environment</a> (Windows PE) uses the same, being a base for separate-boot versions of some antivirus and backup/disaster recovery software.

</p><p>It is also possible to install Windows so that it will always boot from a WIM or VHD file placed on a physical drive. However, this is rarely used since the Windows boot loader is capable of loading the .sys files for boot-time kernel modules itself, which is the task that requires initrd in Linux.

</p>

/* start https://en.wikipedia.org/ */

.mw-parser-output .portalbox{padding:0;margin:0.5em 0;display:table;box-sizing:border-box;max-width:175px;list-style:none}.mw-parser-output .portalborder{border:1px solid var(--border-color-base,#a2a9b1);padding:0.1em;background:var(--background-color-neutral-subtle,#f8f9fa)}.mw-parser-output .portalbox-entry{display:table-row;font-size:85%;line-height:110%;height:1.9em;font-style:italic;font-weight:bold}.mw-parser-output .portalbox-image{display:table-cell;padding:0.2em;vertical-align:middle;text-align:center}.mw-parser-output .portalbox-link{display:table-cell;padding:0.2em 0.2em 0.2em 0.3em;vertical-align:middle}@media(min-width:720px){.mw-parser-output .portalleft{margin:0.5em 1em 0.5em 0}.mw-parser-output .portalright{clear:right;float:right;margin:0.5em 0 0.5em 1em}}

/* end https://en.wikipedia.org/ */

</style>

<ul><li><a href="Dracut_(initramfs)" class="mw-redirect" title="Dracut (initramfs)">dracut</a></li>

<li><a rel="nofollow" class="external text" href="https://github.com/anatol/booster">booster initramfs generator</a></li>

<li><a href="Linux_startup_process" class="mw-redirect" title="Linux startup process">Linux startup process</a></li>

<li><a href="List_of_Linux_distributions_that_run_from_RAM" title="List of Linux distributions that run from RAM">List of Linux distributions that run from RAM</a></li>

<li><a rel="nofollow" class="external text" href="https://wiki.archlinux.org/title/EFI_boot_stub">EFI boot stub</a> (Arch Linux Wiki)</li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}

/* end https://en.wikipedia.org/ */

</style><div class="reflist">

/* start https://en.wikipedia.org/ */

.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}

/* end https://en.wikipedia.org/ */

</style><cite id="CITEREFAlmesberger2000" class="citation cs2">Almesberger, Werner (2000), <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080724162809/http://www.linuxsymposium.org/2000/booting.php">"Booting linux: the history and the future"</a>, <i>Proceedings of the Ottawa Linux Symposium</i>, archived from <a rel="nofollow" class="external text" href="http://www.linuxsymposium.org/2000/booting.php">the original</a> on 24 July 2008</cite></span>

</li>

<li id="cite_note-landley2-2"><span class="mw-cite-backlink">^ <a href="#cite_ref-landley2_2-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-landley2_2-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFLandley2005" class="citation cs2">Landley, Rob (15 March 2005), <a rel="nofollow" class="external text" href="https://landley.net/writing/rootfs-intro.html"><i>Introducing initramfs, a new model for initial RAM disks</i></a></cite></span>

</li>

<li id="cite_note-almesberger-3"><span class="mw-cite-backlink">^ <a href="#cite_ref-almesberger_3-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-almesberger_3-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFAlmesbergerLermen2000" class="citation web cs1">Almesberger, Werner; Lermen, Hans (2000). <a rel="nofollow" class="external text" href="https://web.archive.org/web/20150402090928/https://www.kernel.org/doc/Documentation/initrd.txt">"Using the initial RAM disk (initrd)"</a>. Archived from <a rel="nofollow" class="external text" href="https://www.kernel.org/doc/Documentation/initrd.txt">the original</a> on 2 April 2015<span class="reference-accessdate">. Retrieved <span class="nowrap">14 March</span> 2015</span>.</cite></span>

</li>

<li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://github.com/torvalds/linux/blob/4f671fe2f9523a1ea206f63fe60a7c7b3a56d5c7/init/do_mounts_initrd.c#L74">"linux/do_mounts_initrd.c at 4f671fe2f9523a1ea206f63fe60a7c7b3a56d5c7 · torvalds/linux · GitHub"</a>. <i>GitHub</i>.</cite></span>

</li>

<li id="cite_note-landley-5"><span class="mw-cite-backlink">^ <a href="#cite_ref-landley_5-0"><sup><i><b>a</b></i></sup></a> <a href="#cite_ref-landley_5-1"><sup><i><b>b</b></i></sup></a></span> <span class="reference-text"><cite id="CITEREFLandley2005" class="citation web cs1">Landley, Rob (17 October 2005). <a rel="nofollow" class="external text" href="https://www.kernel.org/doc/Documentation/filesystems/ramfs-rootfs-initramfs.txt">"ramfs, rootfs, and initramfs docs, take 2"</a>. Linux kernel source tree.</cite></span>

</li>

<li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><cite id="CITEREFPetersen2010" class="citation book cs1">Petersen, Richard Leland (2010). <a rel="nofollow" class="external text" href="https://books.google.com/books?id=rQRJG8s1ugQC"><i>Fedora 13: Administration, Networking, Security</i></a>. Alameda, California: Surfing Turtle Press. p. 76. <a href="ISBN_(identifier)" class="mw-redirect" title="ISBN (identifier)">ISBN</a> <bdi>978-1-936280-02-5</bdi>. <q>Dracut uses kernel parameters listed on the GRUB kernel command line to configure the initramfs RAM file system on the fly, providing more flexibiltity and furthercutting down on RAM file system code.</q></cite></span>

</li>

<li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://web.archive.org/web/20170804162458/http://manpages.ubuntu.com/manpages/precise/man7/casper.7.html">"Ubuntu Manpage: casper - a hook for initramfs-tools to boot live systems"</a>. <i>manpages.ubuntu.com</i>. Archived from <a rel="nofollow" class="external text" href="http://manpages.ubuntu.com/manpages/precise/man7/casper.7.html">the original</a> on 4 August 2017<span class="reference-accessdate">. Retrieved <span class="nowrap">7 August</span> 2017</span>.</cite></span>

</li>

<li id="cite_note-8"><span class="mw-cite-backlink"><b><a href="#cite_ref-8">^</a></b></span> <span class="reference-text"><a href="Shawn_Powers" title="Shawn Powers">Shawn Powers</a>. <a rel="nofollow" class="external text" href="http://www.linuxjournal.com/content/casper-friendly-and-persistent-ghost">"Casper, the Friendly (and Persistent) Ghost"</a>. Linux Journal. 2012.</span>

</li>

<li id="cite_note-9"><span class="mw-cite-backlink"><b><a href="#cite_ref-9">^</a></b></span> <span class="reference-text"><cite id="CITEREFKyungsik_Lee2013" class="citation web cs1">Kyungsik Lee (30 May 2013). <a rel="nofollow" class="external text" href="https://events.static.linuxfound.org/sites/events/files/lcjpcojp13_klee.pdf">"LZ4 Compression and Improving Boot Time"</a> <span class="cs1-format">(PDF)</span>. <i>events.linuxfoundation.org</i>. p. 18<span class="reference-accessdate">. Retrieved <span class="nowrap">29 May</span> 2015</span>.</cite></span>

</li>

<li id="cite_note-10"><span class="mw-cite-backlink"><b><a href="#cite_ref-10">^</a></b></span> <span class="reference-text"><cite id="CITEREFFish2005" class="citation web cs1">Fish, Richard (6 July 2005). <a rel="nofollow" class="external text" href="http://bugzilla.kernel.org/show_bug.cgi?id=4857">"pivot_root from initramfs causes circular reference in mount tree"</a>. Linux Kernel Bug Tracker<span class="reference-accessdate">. Retrieved <span class="nowrap">28 February</span> 2009</span>.</cite></span>

</li>

<li id="cite_note-11"><span class="mw-cite-backlink"><b><a href="#cite_ref-11">^</a></b></span> <span class="reference-text"><cite id="CITEREFGarzik2002" class="citation web cs1">Garzik, Jeff (2 November 2002). <a rel="nofollow" class="external text" href="https://lkml.org/lkml/2002/11/2/17">"initramfs merge, part 1 of N"</a>. <a href="Linux_kernel_mailing_list" title="Linux kernel mailing list">Linux kernel mailing list</a>.</cite></span>

</li>

<li id="cite_note-12"><span class="mw-cite-backlink"><b><a href="#cite_ref-12">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="http://distro.ibiblio.org/tinycorelinux/concepts.html">"Tiny Core Linux - Concepts"</a>. <i>ibiblio.org</i>.</cite></span>

</li>

<li id="cite_note-13"><span class="mw-cite-backlink"><b><a href="#cite_ref-13">^</a></b></span> <span class="reference-text"><cite id="CITEREFBarry_Kauler" class="citation web cs1">Barry Kauler. <a rel="nofollow" class="external text" href="http://distro.ibiblio.org/puppylinux/puppy-5.3/release-Slacko-5.3.htm">"Puppy Linux Release Announcement"</a>. <i>ibiblio.org</i>.</cite></span>

</li>

<li id="cite_note-14"><span class="mw-cite-backlink"><b><a href="#cite_ref-14">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://technet.microsoft.com/en-us/library/cc749478%28v=ws.10%29.aspx">"Windows Imaging File Format (WIM)"</a>. <i>microsoft.com</i>. Microsoft.</cite></span>

</li>

<li id="cite_note-15"><span class="mw-cite-backlink"><b><a href="#cite_ref-15">^</a></b></span> <span class="reference-text"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.microsoft.com/en-us/download/details.aspx?id=13096">"Download Windows Imaging File Format (WIM) from Official Microsoft Download Center"</a>. <i>Microsoft.com</i>. Microsoft.</cite></span>

</li>

</ol></div></div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<ul><li><a rel="nofollow" class="external text" href="https://tracker.debian.org/pkg/initramfs-tools">Debian initramfs-tools</a></li>

<li><a rel="nofollow" class="external text" href="https://wiki.debian.org/InitrdReplacementOptions">Detailed comparison</a> of initrd-generating toolkits</li>

<li><a rel="nofollow" class="external text" href="https://www.kernel.org/doc/html/latest/driver-api/early-userspace/early_userspace_support.html">Kernel documentation</a> on early userspace support</li>

<li><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://archive.today/20130104033427/http://www.linuxfordevices.com/c/a/Linux-For-Devices-Articles/Introducing-initramfs-a-new-model-for-initial-RAM-disks/">"Motivation for switch from initrd to initramfs"</a>. Archived from <a rel="nofollow" class="external text" href="http://www.linuxfordevices.com/c/a/Linux-For-Devices-Articles/Introducing-initramfs-a-new-model-for-initial-RAM-disks/">the original</a> on 4 January 2013.</cite> <a rel="nofollow" class="external text" href="https://landley.net/writing/rootfs-intro.html">Alt URL</a></li></ul>

/* start https://en.wikipedia.org/ */

.mw-parser-output .hlist dl,.mw-parser-output .hlist ol,.mw-parser-output .hlist ul{margin:0;padding:0}.mw-parser-output .hlist dd,.mw-parser-output .hlist dt,.mw-parser-output .hlist li{margin:0;display:inline}.mw-parser-output .hlist.inline,.mw-parser-output .hlist.inline dl,.mw-parser-output .hlist.inline ol,.mw-parser-output .hlist.inline ul,.mw-parser-output .hlist dl dl,.mw-parser-output .hlist dl ol,.mw-parser-output .hlist dl ul,.mw-parser-output .hlist ol dl,.mw-parser-output .hlist ol ol,.mw-parser-output .hlist ol ul,.mw-parser-output .hlist ul dl,.mw-parser-output .hlist ul ol,.mw-parser-output .hlist ul ul{display:inline}.mw-parser-output .hlist .mw-empty-li{display:none}.mw-parser-output .hlist dt::after{content:": "}.mw-parser-output .hlist dd::after,.mw-parser-output .hlist li::after{content:" · ";font-weight:bold}.mw-parser-output .hlist dd:last-child::after,.mw-parser-output .hlist dt:last-child::after,.mw-parser-output .hlist li:last-child::after{content:none}.mw-parser-output .hlist dd dd:first-child::before,.mw-parser-output .hlist dd dt:first-child::before,.mw-parser-output .hlist dd li:first-child::before,.mw-parser-output .hlist dt dd:first-child::before,.mw-parser-output .hlist dt dt:first-child::before,.mw-parser-output .hlist dt li:first-child::before,.mw-parser-output .hlist li dd:first-child::before,.mw-parser-output .hlist li dt:first-child::before,.mw-parser-output .hlist li li:first-child::before{content:" (";font-weight:normal}.mw-parser-output .hlist dd dd:last-child::after,.mw-parser-output .hlist dd dt:last-child::after,.mw-parser-output .hlist dd li:last-child::after,.mw-parser-output .hlist dt dd:last-child::after,.mw-parser-output .hlist dt dt:last-child::after,.mw-parser-output .hlist dt li:last-child::after,.mw-parser-output .hlist li dd:last-child::after,.mw-parser-output .hlist li dt:last-child::after,.mw-parser-output .hlist li li:last-child::after{content:")";font-weight:normal}.mw-parser-output .hlist ol{counter-reset:listitem}.mw-parser-output .hlist ol>li{counter-increment:listitem}.mw-parser-output .hlist ol>li::before{content:" "counter(listitem)"\a0 "}.mw-parser-output .hlist dd ol>li:first-child::before,.mw-parser-output .hlist dt ol>li:first-child::before,.mw-parser-output .hlist li ol>li:first-child::before{content:" ("counter(listitem)"\a0 "}

/* end https://en.wikipedia.org/ */

</style><style data-mw-deduplicate="TemplateStyles:r1236075235">

/* start https://en.wikipedia.org/ */

.mw-parser-output .navbox{box-sizing:border-box;border:1px solid #a2a9b1;width:100%;clear:both;font-size:88%;text-align:center;padding:1px;margin:1em auto 0}.mw-parser-output .navbox .navbox{margin-top:0}.mw-parser-output .navbox+.navbox,.mw-parser-output .navbox+.navbox-styles+.navbox{margin-top:-1px}.mw-parser-output .navbox-inner,.mw-parser-output .navbox-subgroup{width:100%}.mw-parser-output .navbox-group,.mw-parser-output .navbox-title,.mw-parser-output .navbox-abovebelow{padding:0.25em 1em;line-height:1.5em;text-align:center}.mw-parser-output .navbox-group{white-space:nowrap;text-align:right}.mw-parser-output .navbox,.mw-parser-output .navbox-subgroup{background-color:#fdfdfd}.mw-parser-output .navbox-list{line-height:1.5em;border-color:#fdfdfd}.mw-parser-output .navbox-list-with-group{text-align:left;border-left-width:2px;border-left-style:solid}.mw-parser-output tr+tr>.navbox-abovebelow,.mw-parser-output tr+tr>.navbox-group,.mw-parser-output tr+tr>.navbox-image,.mw-parser-output tr+tr>.navbox-list{border-top:2px solid #fdfdfd}.mw-parser-output .navbox-title{background-color:#ccf}.mw-parser-output .navbox-abovebelow,.mw-parser-output .navbox-group,.mw-parser-output .navbox-subgroup .navbox-title{background-color:#ddf}.mw-parser-output .navbox-subgroup .navbox-group,.mw-parser-output .navbox-subgroup .navbox-abovebelow{background-color:#e6e6ff}.mw-parser-output .navbox-even{background-color:#f7f7f7}.mw-parser-output .navbox-odd{background-color:transparent}.mw-parser-output .navbox .hlist td dl,.mw-parser-output .navbox .hlist td ol,.mw-parser-output .navbox .hlist td ul,.mw-parser-output .navbox td.hlist dl,.mw-parser-output .navbox td.hlist ol,.mw-parser-output .navbox td.hlist ul{padding:0.125em 0}.mw-parser-output .navbox .navbar{display:block;font-size:100%}.mw-parser-output .navbox-title .navbar{float:left;text-align:left;margin-right:0.5em}body.skin--responsive .mw-parser-output .navbox-image img{max-width:none!important}@media print{body.ns-0 .mw-parser-output .navbox{display:none!important}}

/* end https://en.wikipedia.org/ */

</style></div><div role="navigation" class="navbox" aria-labelledby="Linux634" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><style data-mw-deduplicate="TemplateStyles:r1239400231">

/* start https://en.wikipedia.org/ */

.mw-parser-output .navbar{display:inline;font-size:88%;font-weight:normal}.mw-parser-output .navbar-collapse{float:left;text-align:left}.mw-parser-output .navbar-boxtext{word-spacing:0}.mw-parser-output .navbar ul{display:inline-block;white-space:nowrap;line-height:inherit}.mw-parser-output .navbar-brackets::before{margin-right:-0.125em;content:"[ "}.mw-parser-output .navbar-brackets::after{margin-left:-0.125em;content:" ]"}.mw-parser-output .navbar li{word-spacing:-0.125em}.mw-parser-output .navbar a>span,.mw-parser-output .navbar a>abbr{text-decoration:inherit}.mw-parser-output .navbar-mini abbr{font-variant:small-caps;border-bottom:none;text-decoration:none;cursor:inherit}.mw-parser-output .navbar-ct-full{font-size:114%;margin:0 7em}.mw-parser-output .navbar-ct-mini{font-size:114%;margin:0 4em}html.skin-theme-clientpref-night .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .navbar li a abbr{color:var(--color-base)!important}}@media print{.mw-parser-output .navbar{display:none!important}}

/* end https://en.wikipedia.org/ */

</style><div id="Linux634" style="font-size:114%;margin:0 4em"><a href="Linux" title="Linux">Linux</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Linux_kernel" title="Linux kernel">Linux kernel</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="History_of_Linux" title="History of Linux">History</a></li>

<li><a href="Linus's_law" title="Linus's law">Linus's law</a></li>

<li><a href="Linux-libre" title="Linux-libre">Linux-libre</a></li>

<li><a href="Booting_process_of_Linux" title="Booting process of Linux">Booting process</a></li>

<li><a href="Linux_kernel_oops" title="Linux kernel oops">Kernel oops</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Controversies</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Criticism_of_Linux" title="Criticism of Linux">Criticism of Linux</a></li>

<li><a href="Criticism_of_desktop_Linux" title="Criticism of desktop Linux">Criticism of desktop Linux</a></li>

<li><a href="GNU/Linux_naming_controversy" title="GNU/Linux naming controversy">GNU/Linux naming controversy</a></li>

<li><a href="Tanenbaum%E2%80%93Torvalds_debate" title="Tanenbaum–Torvalds debate">Tanenbaum–Torvalds debate</a></li>

<li><a href="SCO%E2%80%93Linux_disputes" title="SCO–Linux disputes">SCO and Linux</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Linux_distribution" title="Linux distribution">Distributions</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Comparison_of_Linux_distributions" title="Comparison of Linux distributions">General comparison</a></li>

<li><a href="List_of_Linux_distributions" title="List of Linux distributions">Distributions list</a></li>

<li><a href="Comparison_of_netbook-oriented_Linux_distributions" title="Comparison of netbook-oriented Linux distributions">Netbook-specific comparison</a></li>

<li><a href="List_of_Linux_distributions_that_run_from_RAM" title="List of Linux distributions that run from RAM">Distributions that run from RAM</a></li>

<li><a href="Light-weight_Linux_distribution" class="mw-redirect" title="Light-weight Linux distribution">Lightweight</a></li>

<li><a href="Security-focused_operating_system#Linux" title="Security-focused operating system">Security-focused operating system</a></li>

<li><a href="Package_manager" title="Package manager">Package manager</a>

<ul><li><a href="Package_format" title="Package format">Package format</a></li>

<li><a href="List_of_software_package_management_systems" title="List of software package management systems">List of software package managers</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Organizations</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="LinuxChix" title="LinuxChix">LinuxChix</a></li>

<li><a href="Linux_Counter" title="Linux Counter">Linux Counter</a></li>

<li><a href="Linux_Documentation_Project" title="Linux Documentation Project">Linux Documentation Project</a></li>

<li><a href="Linux_Foundation" title="Linux Foundation">Linux Foundation</a></li>

<li><a href="Linux_Mark_Institute" title="Linux Mark Institute">Linux Mark Institute</a></li>

<li><a href="Linux_user_group" title="Linux user group">Linux User Group (LUG)</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Linux_adoption" title="Linux adoption">Adoption</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="List_of_Linux_adopters" title="List of Linux adopters">Adopters</a></li>

<li><a href="Linux_desktop_environments" class="mw-redirect" title="Linux desktop environments">Desktop</a></li>

<li><a href="Linux_on_embedded_systems" title="Linux on embedded systems">Embedded</a></li>

<li><a href="Linux_gaming" class="mw-redirect" title="Linux gaming">Gaming</a></li>

<li><a href="Linux_for_mobile_devices" title="Linux for mobile devices">Mobile</a></li>

<li><a href="Linux_range_of_use" title="Linux range of use">Range of use</a></li>

<li><a href="Linux_malware" title="Linux malware">Linux malware</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Media</th><td class="navbox-list-with-group navbox-list navbox-even hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="DistroWatch" title="DistroWatch">DistroWatch</a></li>

<li><i><a href="Free_Software_Magazine" title="Free Software Magazine">Free Software Magazine</a></i></li>

<li><i><a href="Full_Circle_(magazine)" title="Full Circle (magazine)">Full Circle</a></i></li>

<li><a href="Linux.com" title="Linux.com">Linux.com</a></li>

<li><i><a href="Linux_Format" title="Linux Format">Linux Format</a></i></li>

<li><i><a href="Linux_Gazette" title="Linux Gazette">Linux Gazette</a></i></li>

<li><i><a href="Linux_Journal" title="Linux Journal">Linux Journal</a></i></li>

<li><i><a href="Linux_Magazine" title="Linux Magazine">Linux Magazine</a></i></li>

<li><i><a href="LinuxUser" title="LinuxUser">LinuxUser</a></i>

<ul><li><i><a href="Ubuntu_User" title="Ubuntu User">Ubuntu User</a></i></li></ul></li>

<li><a href="Linux_Outlaws" title="Linux Outlaws">Linux Outlaws</a></li>

<li><i><a href="Linux_Voice" title="Linux Voice">Linux Voice</a></i></li>

<li><a href="LugRadio" title="LugRadio">LugRadio</a></li>

<li><a href="Phoronix_Test_Suite#Phoronix_website" title="Phoronix Test Suite">Phoronix</a></li>

<li><i><a href="Revolution_OS" title="Revolution OS">Revolution OS</a></i></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="List_of_computer_security_certifications" title="List of computer security certifications">Security<br>certifications</a></th><td class="navbox-list-with-group navbox-list navbox-odd hlist" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="CompTIA_Linux%2B" class="mw-redirect" title="CompTIA Linux+">CompTIA Linux+</a></li>

<li><a href="Linux_Foundation_Linux_Certification" class="mw-redirect" title="Linux Foundation Linux Certification">Linux Foundation</a></li>

</div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>

<ul><li><b><span class="nowrap"><span class="noviewer" typeof="mw:File"></span> </span><a href="Portal%3ALinux" title="Portal:Linux">Linux portal</a></b></li>

<li><b><span class="nowrap"><span class="noviewer" typeof="mw:File"><span></span></span> </span><a href="Portal%3AFree_and_open-source_software" title="Portal:Free and open-source software">Free and open-source software portal</a></b></li>

<li><span class="noviewer" typeof="mw:File"><span title="Category"></span></span> <b>Category</b></li></ul>

</div></td></tr></tbody></table></div>

<div class="navbox-styles"></div><div role="navigation" class="navbox" aria-labelledby="Linux_kernel514" style="padding:3px"><table class="nowraplinks hlist mw-collapsible autocollapse navbox-inner" style="border-spacing:0;background:transparent;color:inherit"><tbody><tr><th scope="col" class="navbox-title" colspan="2"><div id="Linux_kernel514" style="font-size:114%;margin:0 4em"><a href="Linux_kernel" title="Linux kernel">Linux kernel</a></div></th></tr><tr><th scope="row" class="navbox-group" style="width:1%">Organization</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="Kernel19" scope="row" class="navbox-group" style="width:1%">Kernel</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Linux_Foundation" title="Linux Foundation">Linux Foundation</a></li>

<li><a href="Linux_Mark_Institute" title="Linux Mark Institute">Linux Mark Institute</a></li>

<li><a href="Linus's_law" title="Linus's law">Linus's law</a></li>

<li><a href="Tanenbaum%E2%80%93Torvalds_debate" title="Tanenbaum–Torvalds debate">Tanenbaum–Torvalds debate</a></li>

<li><a href="SCO%E2%80%93Linux_disputes" title="SCO–Linux disputes">SCO disputes</a></li>

<li><a href="Linaro" title="Linaro">Linaro</a></li>

<li><a href="Menuconfig" title="Menuconfig">menuconfig</a></li>

<li><a href="List_of_Linux-supported_computer_architectures" title="List of Linux-supported computer architectures">Supported computer architectures</a></li>

<li><a href="Linux_kernel_version_history" title="Linux kernel version history">Version history</a></li>

<li><a href="Criticism_of_Linux" title="Criticism of Linux">Criticism</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Support</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li>Developers

<ul><li><i><a href="The_Linux_Programming_Interface" title="The Linux Programming Interface">The Linux Programming Interface</a></i></li>

<li><a href="Kernel.org" title="Kernel.org">kernel.org</a></li>

<li><a href="Linux_conference" class="mw-redirect" title="Linux conference">Linux conferences</a></li></ul></li>

<li>Users

<ul><li><a href="Linux_user_group" title="Linux user group">Linux User Group (LUG)</a></li></ul></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">People</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Werner_Almesberger" title="Werner Almesberger">Werner Almesberger</a></li>

<li><a href="H._Peter_Anvin" title="H. Peter Anvin">H. Peter Anvin</a></li>

<li><a href="Jens_Axboe" title="Jens Axboe">Jens Axboe</a></li>

<li><a href="Moshe_Bar_(investor)" title="Moshe Bar (investor)">Moshe Bar</a></li>

<li><a href="Suparna_Bhattacharya" title="Suparna Bhattacharya">Suparna Bhattacharya</a></li>

<li><a href="Andries_Brouwer" title="Andries Brouwer">Andries Brouwer</a></li>

<li><a href="Matthew_Garrett" title="Matthew Garrett">Matthew Garrett</a></li>

<li><a href="Avi_Kivity" title="Avi Kivity">Avi Kivity</a></li>

<li><a href="Con_Kolivas" title="Con Kolivas">Con Kolivas</a></li>

<li><a href="Greg_Kroah-Hartman" title="Greg Kroah-Hartman">Greg Kroah-Hartman</a></li>

<li><a href="Benson_Leung" title="Benson Leung">Benson Leung</a></li>

<li><a href="Robert_Love" title="Robert Love">Robert Love</a></li>

<li><a href="David_S._Miller" title="David S. Miller">David S. Miller</a></li>

<li><a href="Ingo_Moln%C3%A1r" title="Ingo Molnár">Ingo Molnár</a></li>

<li><a href="Andrew_Morton_(computer_programmer)" title="Andrew Morton (computer programmer)">Andrew Morton</a></li>

<li><a href="Hans_Reiser" title="Hans Reiser">Hans Reiser</a></li>

<li><a href="Rusty_Russell" title="Rusty Russell">Rusty Russell</a></li>

<li><a href="Shuah_Khan" title="Shuah Khan">Shuah Khan</a></li>

<li><a href="Linus_Torvalds" title="Linus Torvalds">Linus Torvalds</a></li>

<li><a href="Theodore_Ts'o" title="Theodore Ts'o">Theodore Ts'o</a></li>

<li><a href="Stephen_Tweedie" title="Stephen Tweedie">Stephen Tweedie</a></li>

<li><a href="Harald_Welte" title="Harald Welte">Harald Welte</a></li>

<li><a href="Chris_Wright_(programmer)" title="Chris Wright (programmer)">Chris Wright</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Technical</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Debugging</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Ftrace" title="Ftrace">ftrace</a></li>

<li><a href="Kdump_(Linux)" title="Kdump (Linux)">kdump</a></li>

<li><a href="Linux_kernel_oops" title="Linux kernel oops">Linux kernel oops</a></li>

<li><a href="SystemTap" title="SystemTap">SystemTap</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Booting_process_of_Linux" title="Booting process of Linux">Startup</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Vmlinux" title="Vmlinux">vmlinux</a></li>

<li><a href="System.map" title="System.map">System.map</a></li>

<li><a href="Dracut_(software)" title="Dracut (software)">dracut</a></li>

<li><a href="Initrd" class="mw-redirect" title="Initrd">initrd</a></li>

<li><a href="Initramfs" class="mw-redirect" title="Initramfs">initramfs</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Linux_kernel_interfaces" title="Linux kernel interfaces">ABIs</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Linux_Standard_Base" title="Linux Standard Base">Linux Standard Base</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Linux_kernel_interfaces" title="Linux kernel interfaces">APIs</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%">Kernel</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Linux_kernel_interfaces#SCI" title="Linux kernel interfaces">System Call<br>Interface</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="POSIX" title="POSIX">POSIX</a>

<ul><li><a href="Ioctl" title="Ioctl">ioctl</a></li>

<li><a href="Select_(Unix)" title="Select (Unix)">select</a></li>

<li><a href="Close_(system_call)" title="Close (system call)">close</a></li>

<li><a href="Linux_kernel_interfaces#Additions_to_POSIX" title="Linux kernel interfaces">Linux-only</a>

<ul><li><a href="Futex" title="Futex">futex</a></li>

<li><a href="Epoll" title="Epoll">epoll</a></li>

<li><a href="Splice_(system_call)" title="Splice (system call)">splice</a></li>

<li><a href="Dnotify" title="Dnotify">dnotify</a></li>

<li><a href="Inotify" title="Inotify">inotify</a></li>

<li><a href="Readahead" title="Readahead">readahead</a></li>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Linux_kernel_interfaces#In–kernel_APIs" title="Linux kernel interfaces">In-kernel</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<li><a href="Crypto_API_(Linux)" title="Crypto API (Linux)">Crypto API</a></li>

<li><a href="Io_uring" title="Io uring">io uring</a></li>

<li><a href="Kernfs_(Linux)" title="Kernfs (Linux)">kernfs</a></li>

<li><a href="Memory_barrier" title="Memory barrier">Memory barrier</a></li>

<li><a href="Video4Linux" title="Video4Linux">Video4Linux</a></li>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="User_space_and_kernel_space" title="User space and kernel space">Userspace</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Daemon_(computing)" title="Daemon (computing)">Daemons</a>,<br><a href="Virtual_file_system" title="Virtual file system">File systems</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li>bpffs</li>

<li><a href="Configfs" title="Configfs">configfs</a></li>

<li><a href="Devfs" class="mw-redirect" title="Devfs">devfs</a></li>

<li><a href="Devpts" title="Devpts">devpts</a></li>

<li><a href="Debugfs" title="Debugfs">debugfs</a></li>

<li>hugetlbfs</li>

<li>pipefs</li>

<li><a href="Procfs" title="Procfs">procfs</a></li>

<li>securityfs</li>

<li>sockfs</li>

<li><a href="Sysfs" title="Sysfs">sysfs</a></li>

<li><a href="Tmpfs" title="Tmpfs">tmpfs</a></li>

<li><a href="Systemd" title="Systemd">systemd</a>

<li><a href="Kmscon" title="Kmscon">Kmscon</a></li>

<li><a href="Binfmt_misc" title="Binfmt misc">binfmt_misc</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Wrapper_library" title="Wrapper library">Wrapper<br>libraries</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="C_standard_library" title="C standard library">C standard library</a>

<ul><li><a href="Glibc" title="Glibc">glibc</a></li>

<li><a href="UClibc" title="UClibc">uClibc</a></li>

<li><a href="Bionic_(software)" title="Bionic (software)">Bionic</a>

<ul><li><a href="Libhybris" title="Libhybris">libhybris</a></li></ul></li>

<li><a href="Dietlibc" title="Dietlibc">dietlibc</a></li>

<li><a href="Embedded_GLIBC" class="mw-redirect" title="Embedded GLIBC">EGLIBC</a></li>

<li><a href="Klibc" title="Klibc">klibc</a></li>

<li><a href="Newlib" title="Newlib">Newlib</a></li></ul></li>

<li><a href="Cgroups" title="Cgroups">libcgroup</a></li>

<li><a href="Direct_Rendering_Manager" title="Direct Rendering Manager">libdrm</a></li>

<li><a href="Advanced_Linux_Sound_Architecture" title="Advanced Linux Sound Architecture">libalsa</a></li>

<li><a href="Evdev" title="Evdev">libevdev</a></li>

<li><a href="Libusb" title="Libusb">libusb</a></li>

<li><a href="Io_uring" title="Io uring">liburing</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Components</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Loadable_kernel_module" title="Loadable kernel module">Kernel modules</a></li>

<li><a href="BlueZ" class="mw-redirect" title="BlueZ">BlueZ</a></li>

<li><a href="Cgroups" title="Cgroups">cgroups</a></li>

<li><a href="Linux_console" title="Linux console">Console</a></li>

<li><a href="Bcache" title="Bcache">bcache</a></li>

<li><a href="Device_mapper" title="Device mapper">Device mapper</a></li>

<li><a href="Dm-cache" title="Dm-cache">dm-cache</a></li>

<li><a href="Dm-crypt" title="Dm-crypt">dm-crypt</a></li>

<li><a href="Evdev" title="Evdev">evdev</a></li>

<li><a href="Kernel_same-page_merging" title="Kernel same-page merging">Kernel same-page merging</a> (KSM)</li>

<li><a href="Linux_framebuffer" title="Linux framebuffer">Framebuffer</a></li>

<li><a href="KMS_driver" class="mw-redirect" title="KMS driver">KMS driver</a></li>

<li><a href="Netfilter" title="Netfilter">Netfilter</a></li>

<li><a href="Netlink" title="Netlink">Netlink</a></li>

<li><a href="Nftables" title="Nftables">nftables</a></li>

<li><a href="Network_scheduler" title="Network scheduler">Network scheduler</a></li>

<li><a href="Zswap" title="Zswap">zswap</a></li></ul>

<ul><li><a href="Scheduling_(computing)#Linux" title="Scheduling (computing)">Process and I/O schedulers</a>:</li>

<li><a href="Brain_Fuck_Scheduler" title="Brain Fuck Scheduler">Brain Fuck Scheduler</a></li>

<li><a href="Completely_Fair_Scheduler" title="Completely Fair Scheduler">Completely Fair Scheduler</a> (CFS)</li>

<li><a href="Earliest_eligible_virtual_deadline_first_scheduling" title="Earliest eligible virtual deadline first scheduling">Earliest eligible virtual deadline first</a> (EEVDF)</li>

<li><a href="Noop_scheduler" title="Noop scheduler">Noop scheduler</a></li>

<li><a href="O(n)_scheduler" title="O(n) scheduler">O(n) scheduler</a></li>

<li><a href="O(1)_scheduler" title="O(1) scheduler">O(1) scheduler</a></li>

<li><a href="SCHED_DEADLINE" title="SCHED DEADLINE">SCHED_DEADLINE</a></li>

<li><a href="SCHED_FIFO" class="mw-redirect" title="SCHED FIFO">SCHED_FIFO</a></li>

<li><a href="SCHED_RR" class="mw-redirect" title="SCHED RR">SCHED_RR</a></li></ul>

<ul><li><a href="Linux_Security_Modules" title="Linux Security Modules">Security Modules</a>: <a href="AppArmor" title="AppArmor">AppArmor</a></li>

<li><a href="Exec_Shield" title="Exec Shield">Exec Shield</a></li>

<li><a href="Seccomp" title="Seccomp">seccomp</a></li>

<li><a href="Security-Enhanced_Linux" title="Security-Enhanced Linux">SELinux</a></li>

<li><a href="Smack_(software)" title="Smack (software)">Smack</a></li>

<li><a href="Tomoyo_Linux" title="Tomoyo Linux">Tomoyo Linux</a></li>

<li><a href="Linux_PAM" title="Linux PAM">Linux PAM</a></li></ul>

<ul><li><a href="Device_driver" title="Device driver">Device drivers</a>

<li><a href="Free_and_open-source_graphics_device_driver" title="Free and open-source graphics device driver">graphics</a></li></ul></li>

<li><a href="Raw_device" title="Raw device">Raw device</a></li></ul>

<ul><li><a href="Initramfs" class="mw-redirect" title="Initramfs">initramfs</a></li>

<li><a href="KernelCare" title="KernelCare">KernelCare</a></li>

<li><a href="Kexec" title="Kexec">kexec</a></li>

<li><a href="KGraft" title="KGraft">kGraft</a></li>

<li><a href="Kpatch" title="Kpatch">kpatch</a></li>

<li><a href="Ksplice" title="Ksplice">Ksplice</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Variants</th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Mainline_Linux" class="mw-redirect" title="Mainline Linux">Mainline</a>

<ul><li><a href="Linux_kernel" title="Linux kernel">Linux kernel</a></li>

<li><a href="Linux-libre" title="Linux-libre">Linux-libre</a></li></ul></li>

<li><a href="High-performance_computing" title="High-performance computing">High-performance computing</a>

<li><a href="Compute_Node_Linux" title="Compute Node Linux">Compute Node Linux</a></li>

<li><a href="Slurm_Workload_Manager" title="Slurm Workload Manager">SLURM</a></li></ul></li>

<li><a href="Real-time_computing" title="Real-time computing">Real-time computing</a>

<ul><li><a href="RTLinux" title="RTLinux">RTLinux</a></li>

<li><a href="Xenomai" title="Xenomai">Xenomai</a></li>

<li><a href="PREEMPT_RT" title="PREEMPT RT">PREEMPT_RT</a></li></ul></li>

<li><a href="Memory_management_unit" title="Memory management unit">MMU</a>-less

<ul><li><a href="%CE%9CClinux" title="ΜClinux">μClinux</a></li>

<li><a href="PSXLinux" title="PSXLinux">PSXLinux</a></li></ul></li></ul>

</div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="Virtualization18" scope="row" class="navbox-group" style="width:1%"><a href="Virtualization" title="Virtualization">Virtualization</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Hypervisor" title="Hypervisor">Hypervisor</a>

<li><a href="OS-level_virtualization" title="OS-level virtualization">OS-level virtualization</a>

<ul><li><a href="Linux-VServer" title="Linux-VServer">Linux-VServer</a></li>

<li><a href="Lguest" title="Lguest">Lguest</a></li>

<li><a href="OpenVZ" title="OpenVZ">OpenVZ</a></li></ul></li>

<li>Other

<ul><li><a href="L4Linux" title="L4Linux">L4Linux</a></li>

<li><a href="User-mode_Linux" title="User-mode Linux">User-mode Linux</a></li>

<li><a href="MkLinux" title="MkLinux">MkLinux</a></li>

<li><a href="Cooperative_Linux" title="Cooperative Linux">coLinux</a></li></ul></li></ul>

</div></td></tr></tbody></table><div>

</div></td></tr></tbody></table><div></div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%"><a href="Linux_adoption" title="Linux adoption">Adoption</a></th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em"></div><table class="nowraplinks navbox-subgroup" style="border-spacing:0"><tbody><tr><th id="Rangeof_use48" scope="row" class="navbox-group" style="width:1%"><a href="Linux_range_of_use" title="Linux range of use">Range<br>of use</a></th><td class="navbox-list-with-group navbox-list navbox-even" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="Linux_desktop_environments" class="mw-redirect" title="Linux desktop environments">Desktop</a></li>

<li><a href="Linux_on_embedded_systems" title="Linux on embedded systems">Embedded</a></li>

<li><a href="Video_games_and_Linux" title="Video games and Linux">Gaming</a></li>

<li>Thin client:

<li>Server:

<li><a href="Linux-powered_device" title="Linux-powered device">Devices</a></li></ul>

</div></td></tr><tr><th scope="row" class="navbox-group" style="width:1%">Adopters</th><td class="navbox-list-with-group navbox-list navbox-odd" style="width:100%;padding:0"><div style="padding:0 0.25em">

<ul><li><a href="List_of_Linux_adopters" title="List of Linux adopters">List of Linux adopters</a></li></ul>

</div></td></tr></tbody></table><div></div></td></tr><tr><td class="navbox-abovebelow" colspan="2"><div>

<ul><li><b><span class="nowrap"><span class="noviewer" typeof="mw:File"></span> </span><a href="Portal%3ALinux" title="Portal:Linux">Linux portal</a></b></li>

<li><span class="noviewer" typeof="mw:File"><span title="Category"></span></span> <b>Category</b></li></ul>

</div></td></tr></tbody></table></div></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-03-20" href="https://en.wikipedia.org/wiki/?title=Initial_ramdisk&oldid=1281383094">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

</div>

</div></div>

</div>

</main>

</div>

</body></html>