finit/doc/build.md

Building

• Introduction
• Configure
• Example
• Running
• Debugging

Introduction

Finit comes with a traditional configure script to control features and optional plugins to enable. It depends on two external libraries:

• libuEv, the event loop
• libite (-lite), much needed frog DNA

NOTE: Most free/open source software that uses configure default to install to /usr/local. However, some Linux distributions do no longer search that path for installed software, e.g. Fedora and Alpine Linux. To get finit's configure script to find its dependencies you have to help the pkg-config tool a bit if you do not change the default prefix path:

PKG_CONFIG_LIBDIR=/usr/local/lib/pkgconfig ./configure

The configure script checks for all dependencies, including the correct version of the above mentioned libraries. Currently requried versions:

• libite v2.2.0
• libuEv v2.2.0

Configure

Below are a few of the main switches to configure:

• --prefix=..: Usually you want to set this to /usr, default is the GNU default: /usr/local

• --exec-prefix=..: This you want to set to the empty string, or /, to ensure the programs finit and initctl are installed to the proper locations. Linux expects an "init" in /sbin, default: --prefix

• --sysconfdir=..: follows --prefix, you likely want it to be /etc

• --localstatedir=..: follows --prefix, you likely want /var

• --enable-static: Build Finit statically. The plugins will be built-ins (.o files) and all external libraries, except the C library will be linked statically.

• --enable-alsa-utils-plugin: Enable the optional alsa-utils.so sound plugin.

• --enable-dbus-plugin: Enable the optional D-Bus dbus.so plugin.

• --enable-resolvconf-plugin: Enable the resolvconf.so optional plugin.

• --enable-x11-common-plugin: Enable the optional X Window x11-common.so plugin.

For more configure flags, see ./configure --help

Example

First, unpack the archive:

$ tar xf finit-3.0.tar.xz
$ cd finit-3.0/

Then configure, build and install:

$ ./configure --prefix=/usr                 --exec-prefix=                    \
              --sysconfdir=/etc             --localstatedir=/var              \
              --with-heading="Alpine Linux 3.13" --with-hostname=alpine
$ make
.
.
.
$ DESTDIR=/tmp/finit make install

In this example the finit-3.0.tar.xz archive is unpacked to the user's home directory, configured, built and installed to a temporary staging directory. The environment variable DESTDIR controls the destination directory when installing, very useful for building binary standalone packages.

Finit 3.0 and later can detect if it runs on an embedded system, or a system that use BusyBox tools instead of udev & C:o. On such systems mdev instead of udev is used. However, remember to also change the Linux config to:

CONFIG_UEVENT_HELPER_PATH="/sbin/mdev"

Note: If you run into problems starting Finit, take a look at finit.c. One of the most common problems is a custom Linux kernel build that lack CONFIG_DEVTMPFS. Another is too much cruft in the system /etc/fstab.

Running

Having successfully built Finit it is now be time to take it for a test drive. The make install attempts to set up finit as the system system init, /sbin/init, but this is usually a symlink pointing to the current init.

So either change the symlink, or change your boot loader (GRUB, LOADLIN, LILO, U-Boot/Barebox or RedBoot) configuration to append the following to the kernel command line:

append="init=/sbin/finit"

Remember to also set up an initial /etc/finit.conf before rebooting!

Recovery

To rescue a system with Finit, append the following to the kernel command line:

append="init=/sbin/finit rescue"

This tells Finit to start in a very limited recovery mode, no services are loaded, no filesystems are mounted or checked, and no networking is enabled. The default Finit rescue mode configuration is installed into /lib/finit/rescue.conf, which can be safely removed or changed.

By default the a root shell, without login, is started.

Debugging

Edit, or append to, the kernel command line: remove quiet to enable kernel messages and add debug to enable Finit debug messages.

append="init=/sbin/finit debug"

To debug startup issues, in particular issues with getty/login, add the following to your Finit .conf file:

tty [12345789] notty noclear

The notty option ensures reusing the stdin/stdout set up by the kernel. Remember, this is only for debugging and would leave your production system potentially wide open.

There is also a rescue shell available, in case Finit crashes and the kernel usually reboots: configure --enable-emergency-shell. However, the behavior of Finit is severely limited when this is enabled, so use it only for debugging start up issues when Finit crashes.

NOTE: Neither of these options should be enabled on production systems since they can potentially give a user root access.