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Diffstat (limited to 'docs/INITRD_INTERFACE.md')
| -rw-r--r-- | docs/INITRD_INTERFACE.md | 27 |
1 files changed, 14 insertions, 13 deletions
diff --git a/docs/INITRD_INTERFACE.md b/docs/INITRD_INTERFACE.md index 7e8f028ef8..6a54f9f7a6 100644 --- a/docs/INITRD_INTERFACE.md +++ b/docs/INITRD_INTERFACE.md @@ -8,15 +8,16 @@ SPDX-License-Identifier: LGPL-2.1-or-later # The initrd Interface of systemd -The Linux initrd mechanism (short for "initial RAM disk") refers to a small -file system archive that is unpacked by the kernel and contains the first -userspace code that runs. It typically finds and transitions into the actual -root file system to use. systemd supports both initrd and initrd-less boots. If -an initrd is used, it is a good idea to pass a few bits of runtime information -from the initrd to systemd in order to avoid duplicate work and to provide -performance data to the administrator. In this page we attempt to roughly -describe the interfaces that exist between the initrd and systemd. These -interfaces are currently used by dracut and the ArchLinux initrds. +The Linux initrd mechanism (short for "initial RAM disk", also known as +"initramfs") refers to a small file system archive that is unpacked by the +kernel and contains the first userspace code that runs. It typically finds and +transitions into the actual root file system to use. systemd supports both +initrd and initrd-less boots. If an initrd is used, it is a good idea to pass a +few bits of runtime information from the initrd to systemd in order to avoid +duplicate work and to provide performance data to the administrator. In this +page we attempt to roughly describe the interfaces that exist between the +initrd and systemd. These interfaces are currently used by dracut and the +ArchLinux initrds. * The initrd should mount `/run/` as a tmpfs and pass it pre-mounted when jumping into the main system when executing systemd. The mount options should @@ -57,10 +58,10 @@ It's all already implemented there! It is also possible and recommended to implement the initrd itself based on systemd. Here are a few terse notes: -* Provide `/etc/initrd-release` in the initrd image. The idea is that it follows - the same format as the usual `/etc/os-release` but describes the initial RAM - disk implementation rather than the OS. systemd uses the existence of this - file as a flag whether to run in initial RAM disk mode, or not. +* Provide `/etc/initrd-release` in the initrd image. The idea is that it + follows the same format as the usual `/etc/os-release` but describes the + initrd implementation rather than the OS. systemd uses the existence of this + file as a flag whether to run in initrd mode, or not. * When run in initrd mode, systemd and its components will read a couple of additional command line arguments, which are generally prefixed with `rd.` |