Hello list,
Like I said in my previous post, I have successfully installed systemd
on my LFS-based system, and since people have shown interest I post it
here so everyone else can try it. Regarding the comments on replacing
sysvinit, I think systemd is not ready for this just yet, but I do think
that sysvinit is slowly becoming obsolete, and a newer init system like
systemd eventually will find its way into the base LFS book, sooner or
later.
Before I begin with the instructions, I would like to clear up one
misconception: systemd is *not* all about booting faster or in parallel.
Rather, it is about managing the system, starting and stopping sessions
and services, monitoring mount points, controlling the runtime
environment of each process, and so on. Of course, as the init process,
its first responsibility is to bring up user space, and it should try to
do that as fast as it can, like any other process. But that's not its
main purpose, as far as I understand it.
Also, please note that this is a young project, and there are still
obvious bugs, ugly interfaces, and some orientation towards big
distributions (especially fedora). Furthermore, my system is probably
very different from yours, so you might need to take some extra steps
beyond what is described here. However, the installation procedure does
not overwrite the existing binaries from sysvinit or the LFS init
scripts, so you should be able to install systemd just to test it and go
back to sysvinit if anything goes wrong.
I guess some of you would be interested in this nonetheless, so I tried
to check how much time each of the two systems (sysvinit and systemd)
takes to boot up. I booted 4 times in a row for each system, and these
were the results (in seconds):
sysvinit: 8.40 8.47 8.11 8.72
systemd: 6.99 7.12 7.48 7.27
When shutting the system down, systemd takes about 1 second, while
sysvinit with the LFS init scripts take about 10 seconds, so I did not
bother to make an exact measurement.
Prerequisites
-------------
The README file describes the following dependencies:
Linux kernel >= 2.6.30 (with devtmpfs, cgroups; optional but
strongly recommended: autofs4, ipv6)
libudev >= 172
dbus >= 1.4.0
libcap
gtk+ >= 2.20 (optional)
PAM >= 1.1.2 (optional)
libcryptsetup (optional)
libaudit (optional)
libselinux (optional)
tcpwrappers (optional)
libnotify (optional)
It is also suggested to install nss-myhostname in order to use
systemd-hostnamed. I also noted that the systemd-analyze tool requires
dbus-python binding in order to run. However, these two packages, and
the packages marked as optional in the README file, are not required,
and systemd can be built and run without them.
Preparations
------------
First, /etc/mtab should be a symbolic link to /proc/self/mounts.
Apparently, this is not specific to systemd, but the new recommended way
to setup this file on Linux systems. To create the link, run the
following command as the root user:
ln -sfv /proc/self/mounts /etc/mtab
systemd uses a number of configuration files, which are intended to
replace distribution-specific configuration files related to console
fonts, kernel modules, temporary files, and other system parameters. Of
these configuration files, only /etc/hostname is really essential, while
the others have reasonable defaults that should work out-of-the-box.
Create /etc/hostname by running the following command as the root user:
grep '^HOSTNAME=' /etc/sysconfig/network | sed 's/^HOSTNAME=//'
>/etc/hostname
You can read about the other configuration files in the manual pages
that come with systemd:
binfmt.d(5) - additional binary formats to register at boot
locale.conf(5) - locale-related configuration settings
modules-load.d(5) - kernel modules to load at boot
os-release(5) - system name and version information, similar in
purpose to /etc/lfs-release
sysctl.d(5) - kernel parameters to apply at boot
systemd.conf(5) - general settings for systemd itself
tmpfiles.d(5) - creation and clean up of temporary files
vconsole.conf(5) - configuration of the virtual console (font, keymap,
etc)
There are also machine-id(5) and machine-info(5), but I didn't quite
understand their use. systemd also recognizes several options that you
can pass on the kernel command line. See the manual pages mentioned
above and also systemd(1) for more information on these options.
On my system, I also needed to create a group named "lock". If this
group does not exist on your system, create it by running the following
command as the root user:
groupadd -g 54 lock
Installation
------------
As noted above, installation of systemd should not overwrite any files
provided by sysvinit (except for 6 manual pages). You can download the
package from here:
http://www.freedesktop.org/software/systemd/
After downloading and unpacking the package, cd into the unpacked
directory and run these commands to compile it:
./configure --prefix=/ --with-rootdir=/ --with-distro=other
--with-sysvinit-path= --with-sysvrcd-path=
make
Then, as the root user, run "make install" to install the package.
After installing systemd, you should re-install udev and dbus, in order
to install their service files for use by systemd.
Further configuration
---------------------
In order to bring up the network on boot, create and enable a network
service by running the following commands:
cat >/etc/systemd/system/network.service <<EOF
[Unit]
Description=Bring up network interfaces
Before=network.target
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/etc/rc.d/init.d/network start
ExecStop=/etc/rc.d/init.d/network stop
[Install]
WantedBy=multi-user.target
EOF
systemctl enable network.service
systemd also has a feature called "read-ahead", which is supposed to
speed up the boot process, but on my system it actually slows it down by
about half a second (even when I tried to boot with it multiple times).
If you want to try it, run these commands as the root user:
systemctl enable systemd-readahead-collect.service
systemctl enable systemd-readahead-replay.service
To undo this, run again as the root user:
systemctl disable systemd-readahead-collect.service
systemctl disable systemd-readahead-replay.service
The above commands (enable and disable) may not work if you are using a
symlink-style package management system. If this is the case, you can
create or remove the necessary symbolic links manually. To enable
read-ahead this way, run these commands as the root user:
ln -sv /lib/systemd/system/systemd-readahead-collect.service
/etc/systemd/system/multi-user.target.wants/
ln -sv /lib/systemd/system/systemd-readahead-replay.service
/etc/systemd/system/multi-user.target.wants/
And to disable:
rm
/etc/systemd/system/multi-user.target.wants/systemd-readahead-collect.service
rm
/etc/systemd/system/multi-user.target.wants/systemd-readahead-replay.service
I haven't tried this method, but it should work, and it's officially
supported and documented.
Boot
----
After following the above instructions, you should be able to boot
normally and use sysvinit as you normally do. In order to boot with
systemd instead, add "init=/bin/systemd" to the kernel command line.
I hope you found this information useful, and of course any questions or
comments are welcome.
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