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Break out building and bootstrap to separate files

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Signed-off-by: Joachim Nilsson <troglobit@gmail.com>
This commit is contained in:
Joachim Nilsson
2016-07-23 00:25:14 +02:00
parent 82e483d6c7
commit 72a484b639
3 changed files with 168 additions and 150 deletions
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README.md
+17 -150
View File
@@ -20,13 +20,13 @@ Table of Contents
* [/etc/finit.conf](doc/config.md#etcfinitconf)
* [/etc/finit.d](doc/config.md#etcfinitd)
* [Runparts & /etc/rc.local](#runparts--etcrclocal)
* [Bootstrap](#bootstrap)
* [Bootstrap](doc/bootstrap.md#bootstrap)
* [Runlevels](#runlevels)
* [Inetd](doc/inetd.md#inetd)
* [Hooks, Callbacks & Plugins](doc/plugins.md#hooks-callbacks--plugins)
* [Rebooting & Halting](#rebooting--halting)
* [Commands & Status](#commands--status)
* [Building](#building)
* [Building](doc/build.md#building)
* [Running](#running)
* [Debugging](#debugging)
* [Origin & References](#origin--references)
@@ -43,13 +43,14 @@ fully functional on standard server and desktop installations as well.
Traditional [SysV init][4] style systems are scripted. For low-resource
embedded systems this is quite resource intensive and often leads to
long boot times. Finit reduces context switches and forking of shell
scripts to provide a system bootstrap written entirely in C.
scripts to provide a swift [system bootstrap](doc/bootstrap.md) written
entirely in C.
There is no `/etc/init.d/rcS` script, or similar. Instead configuration
is read from the main [/etc/finit.conf](doc/config.md#etcfinitconf),
which details kernel modules to load and bootstrap services to start.
After initial bootstrap, including setting up networking,
[/etc/finit.d/](doc/config.md#etcfinitd) and the familiar
After initial [bootstrap](doc/bootstrap.md), including setting up
networking, [/etc/finit.d/](doc/config.md#etcfinitd) and the familiar
[/etc/rc.local](#runparts--etcrclocal) are run.
**Example /etc/finit.conf:**
@@ -186,51 +187,8 @@ and `/etc/rc.local`, in that order if they exist.
No configuration stanza in `/etc/finit.conf` is required for `rc.local`.
If it exists and is an executable shell script, finit calls it at the
very end of the boot, before calling the `HOOK_SYSTEM_UP`. See more on
hooks in [doc/plugins.md](doc/plugins.md#hooks), and the system bootstrap
below.
Bootstrap
---------
1. Populate `/dev`
2. Parse `/etc/finit.conf`
3. Load all `.so` plugins
4. Remount/Pivot `/` to get R+W
5. Call 1st level hooks, `HOOK_ROOTFS_UP`
6. Mount `/etc/fstab` and swap, if available
7. Cleanup stale files from `/tmp/*` et al
8. Enable SysV init signals
9. Call 2nd level hooks, `HOOK_BASEFS_UP`
10. Start all 'S' runlevel tasks and services
11. Load kernel parameters from `/etc/sysctl.conf`
12. Set hostname and bring up loopback interface
13. Call `network` script, if set in `/etc/finit.conf`
14. Call 3rd level hooks, `HOOK_NETWORK_UP`
15. Load all `*.conf` files in `/etc/finit.d/` and switch to the active
active runlevel, as set in `/etc/finit.conf`, default is 2. Here is
where the rest of all tasks and inetd services are started.
16. Call 4th level hooks, `HOOK_SVC_UP`
17. If `runparts <DIR>` is set, [run-parts(8)][] is called on `<DIR>`
18. Call `/etc/rc.local`, if it exists and is an executable shell script
19. Call 5th level (last) hooks, `HOOK_SYSTEM_UP`
20. Start TTYs defined in `/etc/finit.conf`, or rescue on `/dev/console`
In (10) and (15) tasks and services defined in `/etc/finit.conf` are
started. Remember, all `service` and `task` stanzas are started in
parallel and `run` in sequence, and in the order listed. Hence, to
emulate a SysV `/etc/init.d/rcS` one could write a long file with only
`run` statements.
Notice the five hook points that are called at various point in the
bootstrap process. This is where plugins can extend the boot in any way
they please.
For instance, at `HOOK_BASEFS_UP` a plugin could read an XML file from a
USB stick, convert/copy its contents to the system's `/etc/` directory,
well before all 'S' runlevel tasks are started. This could be used with
system images that are created read-only and all configuration is stored
on external media.
hooks in [doc/plugins.md](doc/plugins.md#hooks), and about the system
bootstrap in [doc/bootstrap.md](doc/bootstrap.md).
Runlevels
@@ -367,112 +325,24 @@ Dropbear SSH service will not be restarted if it is killed or exits.
6:2 inetd 0 [345] /sbin/dropbear allow *:22 deny eth0
```
Building
--------
Finit comes with a traditional configure script to control features and
optional plugins to enable. It does however depend on two external
libraries that provide some frog DNA needed:
- [libuEv][]
- [libite][] (-lite)
Like most free/open source software that uses `configure` they deafult
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
Below are a few of the main switches to
configure:
* `--disable-inetd`: Disable the built-in inetd server.
* `--enable-embedded`: Target finit for BusyBox getty and mdev instead
of a standard Linux distribution with GNU tools and udev.
* `--enable-rw-rootfs`: Most desktop and server systems boot with the
root file stystem read-only. With this setting Finit will remount it
as read-write early at boot so the `bootmisc.so` plugin can run.
Usually not needed on embedded systems.
* `--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`: Enable the optional `alsa-utils.so` sound plugin.
* `--enable-dbus`: Enable the optional D-Bus `dbus.so` plugin.
* `--enable-lost`: Enable noisy example plugin for `HOOK_SVC_LOST`.
* `--enable-resolvconf`: Enable the `resolvconf.so` optional plugin.
* `--enable-x11-common`: Enable the optional X Window `x11-common.so` plugin.
For more configure flags, see <kbd>./configure --help</kbd>
**Example**
First, unpack the archive:
```shell
$ tar xf finit-3.0.tar.xz
$ cd finit-3.0/
```
Then configure, build and install:
```shell
$ ./configure --enable-embedded --enable-rw-rootfs --enable-inetd-echo-plugin \
--enable-inetd-chargen-plugin --enable-inetd-daytime-plugin \
--enable-inetd-discard-plugin --enable-inetd-time-plugin \
--with-heading="Alpine Linux 3.4" --with-hostname=alpine
$ make
.
.
.
$ DESTDIR=/tmp/finit make install
```
In this example the [finit-3.0.tar.xz][10] 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.
To target an embedded Linux system, usally a system that use BusyBox
tools instead of udev & C:o, add <kbd>--enable-embedded</kbd> to the
configure command above. This enables `mdev` instead of `udev` and the
BusyBox `getty` syntax. 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
-------
The default install does not setup finit as the system default
`/sbin/init`, neither does it setup an initial `/etc/finit.conf`.
Having successfully [built Finit](doc/build.md) it may 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.
It is assumed that users of finit are competent enough to either setup
finit as their default `/sbin/init` or alter their respective GRUB,
LOADLIN, LILO, U-Boot/Barebox or RedBoot boot loader configuration to
give the kernel the following extra command line:
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:
```shell
init=/sbin/finit
```
Remember to also set up an initial `/etc/finit.conf` before rebooting!
![Finit starting Debian 6.0](images/finit-screenshot.jpg "Finit screenshot")
@@ -506,15 +376,12 @@ and proposed extensions.
[4]: http://en.wikipedia.org/wiki/Init
[5]: http://en.wikipedia.org/wiki/Runlevel
[9]: https://github.com/troglobit/troglos
[10]: ftp://troglobit.com/finit/finit-3.0.tar.xz
[run-parts(8)]: http://manpages.debian.org/cgi-bin/man.cgi?query=run-parts
[original finit]: http://helllabs.org/finit/
[EeePC fastinit]: http://wiki.eeeuser.com/boot_process:the_boot_process
[Claudio Matsuoka]: https://github.com/cmatsuoka
[Joachim Nilsson]: http://troglobit.com
[GitHub]: https://github.com/troglobit/finit
[libuEv]: https://github.com/troglobit/libuev
[libite]: https://github.com/troglobit/libite
[Travis]: https://travis-ci.org/troglobit/finit
[Travis Status]: https://travis-ci.org/troglobit/finit.png?branch=master
[Coverity Scan]: https://scan.coverity.com/projects/3545
doc/bootstrap.md
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@@ -0,0 +1,52 @@
Bootstrap
=========
1. Populate `/dev`
2. Parse `/etc/finit.conf`
3. Load all `.so` plugins
4. Remount/Pivot `/` to get R+W
5. Call 1st level hooks, `HOOK_ROOTFS_UP`
6. Mount `/etc/fstab` and swap, if available
7. Cleanup stale files from `/tmp/*` et al
8. Enable SysV init signals
9. Call 2nd level hooks, `HOOK_BASEFS_UP`
10. Start all 'S' runlevel tasks and services
11. Load kernel parameters from `/etc/sysctl.conf`
12. Set hostname and bring up loopback interface
13. Call `network` script, if set in `/etc/finit.conf`
14. Call 3rd level hooks, `HOOK_NETWORK_UP`
15. Switch to the configured runlevel from `/etc/finit.conf`, default 2.
At every runlevel change all `*.conf` files in `/etc/finit.d/` are
(re)loaded and new services, tasks, and blocking run commands are
started. Provided they are allowed in the new runlevel and all of
their conditions, if any, are set.
16. Call 4th level hooks, `HOOK_SVC_UP`
17. If `runparts <DIR>` is set, [run-parts(8)][] is called on `<DIR>`
18. Call `/etc/rc.local`, if it exists and is an executable shell script
19. Call 5th level (last) hooks, `HOOK_SYSTEM_UP`
20. Start TTYs defined in `/etc/finit.conf`, or rescue on `/dev/console`
In (10) and (15) tasks and services defined in `/etc/finit.conf` are
started. Remember, all `service` and `task` stanzas are started in
parallel and `run` in sequence, and in the order listed. Hence, to
emulate a SysV `/etc/init.d/rcS` one could write a long file with only
`run` statements.
Notice the five hook points that are called at various point in the
bootstrap process. This is where plugins can extend the boot in any way
they please.
For instance, at `HOOK_BASEFS_UP` a plugin could read an XML file from a
USB stick, convert/copy its contents to the system's `/etc/` directory,
well before all 'S' runlevel tasks are started. This could be used with
system images that are created read-only and all configuration is stored
on external media.
[run-parts(8)]: http://manpages.debian.org/cgi-bin/man.cgi?query=run-parts
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doc/build.md
+99
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@@ -0,0 +1,99 @@
Building
========
Finit comes with a traditional configure script to control features and
optional plugins to enable. It does however depend on two external
libraries that provide some frog DNA needed:
- [libuEv][]
- [libite][] (-lite)
Like most free/open source software that uses `configure` they deafult
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
Below are a few of the main switches to
configure:
* `--disable-inetd`: Disable the built-in inetd server.
* `--enable-embedded`: Target finit for BusyBox getty and mdev instead
of a standard Linux distribution with GNU tools and udev.
* `--enable-rw-rootfs`: Most desktop and server systems boot with the
root file stystem read-only. With this setting Finit will remount it
as read-write early at boot so the `bootmisc.so` plugin can run.
Usually not needed on embedded systems.
* `--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`: Enable the optional `alsa-utils.so` sound plugin.
* `--enable-dbus`: Enable the optional D-Bus `dbus.so` plugin.
* `--enable-lost`: Enable noisy example plugin for `HOOK_SVC_LOST`.
* `--enable-resolvconf`: Enable the `resolvconf.so` optional plugin.
* `--enable-x11-common`: Enable the optional X Window `x11-common.so` plugin.
For more configure flags, see <kbd>./configure --help</kbd>
**Example**
First, unpack the archive:
```shell
$ tar xf finit-3.0.tar.xz
$ cd finit-3.0/
```
Then configure, build and install:
```shell
$ ./configure --enable-embedded --enable-rw-rootfs --enable-inetd-echo-plugin \
--enable-inetd-chargen-plugin --enable-inetd-daytime-plugin \
--enable-inetd-discard-plugin --enable-inetd-time-plugin \
--with-heading="Alpine Linux 3.4" --with-hostname=alpine
$ make
.
.
.
$ DESTDIR=/tmp/finit make install
```
In this example the [finit-3.0.tar.xz][1] 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.
To target an embedded Linux system, usally a system that use BusyBox
tools instead of udev & C:o, add <kbd>--enable-embedded</kbd> to the
configure command above. This enables `mdev` instead of `udev` and the
BusyBox `getty` syntax. 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`.
[1]: ftp://troglobit.com/finit/finit-3.0.tar.xz
[libuEv]: https://github.com/troglobit/libuev
[libite]: https://github.com/troglobit/libite
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