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Revision as of 18:08, 1 May 2017 by TemptorSent (talk | contribs) (Boot Process: - Add module handling)
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Alpine uses packages in the .apk file format.

Package Management Tools

Package Building Tools

Boot Process

Boot Loader






  • vanilla
  • hardened
  • virthardened
  • rpi


Command line options

  • modules="<modules>" - specify list of modules to be loaded by initramfs /init needed to mount real root filesystem.


The kernel will decompress the stream of compressed cpio archives passed to it by the 'append' bootloader option to the root of 'rootfs', a tmpfs automatically mounted at '/' by the kernel at boot.

'/init' Script

Not to be confused with '/sbin/init', the '/init' script in the root of the 'rootfs' is called by the kernel upon completion of its boot process, and is responsible for doing whatever steps are necessary to mount the real root file system to '/' and transfer control to '/sbin/init'.

  • Parses kernel command line options.
  • Uses nlplug-findfs to discover devices.

Initfs Module Handling

Modules required to mount the root filesystem and boot must either built into the kernel or available from with the initramfs filesystem through use of appended initrd cpio.gz files provided by the bootloader.

The /init script will first modprobe the modules specified by the modules= kernel command line option and by the name of the specified rootfs type. It will then load the contents of /etc/modules, which may include module options. Modules may be blacklisted from autoprobing (but NOT explicit insertion!) using the blacklist= kernel command line option which appends blacklist entries to '/etc/modprobe.d/boot-opt-blacklist.conf'.

Minimal Required Set

Directory Structure
  • / /bin /boot /dev /etc /lib /lib/modules /media /media/cdrom /media/usb /mnt /proc /sbin /sys /usr /usr/bin /usr/sbin
  • /dev/null
  • /dev/console
  • /dev/kmsg
  • /proc
  • /sys
  • /dev (can be disabled?)
  • /etc/passwd
  • /etc/group
  • /etc/fstab

Feature Sets

Feature sets consist of lists for the set of modules and files that need to be included in a final initramfs to support the indicated feature.


Not to be confused with the '/init' script in the initramfs, '/sbin/init' is the first process to be started in the live system after the initramfs completes its work.

Module Loading

'/etc/init.d/modules' loads all modules specified in '/etc/modules' and '/(etc|run|usr/lib|lib)/modules-load.d/*.conf'