Fedora26 (Rawhide)-- have successfully configured system to boot and run without any running instances of systemd

firejuggler86 · 11-21-2016, 09:00 PM

I now have a fedora26 system running on SysV init instead of systemd, which, according to all sources that I could find online, is an impossible setup. This "project" of mine is in its VERY early stages, so, as would be expected, not everything works yet. However, based on the vast array of programs and functions that DO work without problems, and that also have systemd listed as dependencies, I am very seriously starting to question the credibility of declared dependencies of packages.

(I have not at this time *removed* the systemd files, and have no immediate plans to do so-- mainly to satisfy dependencies. But the fact that those programs whose dependencies I am satisfying by keeping systemd in place have full functionality while there are no systemd processes running on the system at all is why I question whether or not that dependency should even exist.)

For example, the package manager, DNF. Since I've been booting with sysvinit, I have had absolutely *ZERO* DNF related issues. None. Packages still install just as they should, system updates still update as one would expect them to, etc.. I decided to run the command "dnf remove systemd" (not to actually remove it, but to have a look at what removing it would do to the system). I got the error message that the package manager itself requires systemd. Yet, systemd is not running on the system and the package manager still works.

This does not make sense to me. If dnf TRULY needed systemd, then I would expect dnf to not work while systemd is sitting there inactive. Yet, dnf does work. I have heard similar accounts of other packages that supposedly require systemd, but they are known to still run with full functionality without systemd. It makes me feel as though we are being told things that are not true in order to lock us into being dependent on certain programs and software...in other words, to take away users' freedom. Can anyone provide a concrete reason why dnf would depend on systemd? Beyond, "your distribution knows what's best-- just trust them, no questioning allowed"? If there is a legitimate reason, I would truly like to know.. I like to understand the inter-workings of my system as thoroughly as I possibly can.

Thanks!

Emerson · 11-21-2016, 09:04 PM

Good job! Keep it going, I'm curious.

syg00 · 11-21-2016, 09:31 PM

How are you (re-)building the initramfs ?.

happydog500 · 11-22-2016, 12:46 PM

Thank you for your work.
The whole Systemd thing didn't make sense to me. Be careful, some think that just asking about Systemd is some kind of major crime.

Chris.

notKlaatu · 11-22-2016, 01:07 PM

Quote:

Originally Posted by firejuggler86

Can anyone provide a concrete reason why dnf would depend on systemd? Beyond, "your distribution knows what's best-- just trust them, no questioning allowed"? If there is a legitimate reason, I would truly like to know.. I like to understand the inter-workings of my system as thoroughly as I possibly can.

Who told you that dnf required systemd? Maybe the rpm to install dnf depends on systemd (because its spec file lists it as a requirement) but if you look at the source code of dnf, it's pretty clear that systemd is not required.

szboardstretcher · 11-22-2016, 01:17 PM

Yes. The 'dnf' package 'says' it requires systemd:

Code:

[root@tools ~]# yum deplist dnf
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirror.solarvps.com
 * epel: mirror.math.princeton.edu
 * extras: mirror.netdepot.com
 * nux-dextop: mirror.li.nux.ro
 * updates: centos.chi.host-engine.com
package: dnf.noarch 0.6.4-2.el7
  dependency: /bin/sh
   provider: bash.x86_64 4.2.46-20.el7_2
  dependency: python-dnf = 0.6.4-2.el7
   provider: python-dnf.noarch 0.6.4-2.el7
  dependency: systemd
   provider: systemd.x86_64 219-19.el7_2.13

Also I looked at the source code, and it has systemd mentioned a few times.

https://github.com/rpm-software-mana...C%93&q=systemd

But I don't see anything that says systemd is required. Perhaps the options just get configured as 'off' when compiled.

notKlaatu · 11-22-2016, 01:27 PM

firejuggler86, you should look at the sources of applications and not the ready-made packages, especially since you are presumably re-building a lot of them anyway. What a package tells you is required is not necessarily what `ldd` will tell you.

A package is arbitrary. The author(s) can define anything in a package, whether it's actually required for compilation, runtime, or not required at all. Saying that the ready-made dnf rpm requires systemd is not the same as saying that the executable 'dnf' requires systemd.

Code:

$ find ./dnf.clone -type f -exec grep -iH systemd {} \;
[...]
dnf.clone/dnf.spec:BuildRequires:  systemd
dnf.clone/dnf.spec:Requires(post):     systemd
dnf.clone/dnf.spec:Requires(preun):    systemd
dnf.clone/dnf.spec:Requires(postun):   systemd
dnf.clone/dnf.spec:Requires:       rpm-plugin-systemd-inhibit
dnf.clone/dnf.spec:Requires:       rpm-plugin-systemd-inhibit
dnf.clone/dnf.spec:BuildRequires:  systemd
dnf.clone/dnf.spec:Requires(post):   systemd
dnf.clone/dnf.spec:Requires(preun):  systemd
dnf.clone/dnf.spec:Requires(postun): systemd
[...]

If you're rebuilding the Fedora distribution to exist without systemd, you should 1) post your work somewhere so everyone can benefit, because you're doing amazing work and 2) ignore what Fedora packaging is telling you (because Fedora naturally assumes that systemd is part of the core) and look at the source (which will not assume systemd).

Good luck.

goumba · 11-22-2016, 02:29 PM

Dare I play devil's advocate and say that the only way you'll truly find out if systemD is inactive is by maybe truncating the binary or libraries to 0 bytes? Just because it's not running as an init system, doesn't mean the other applications aren't using parts of it in other ways.