[systemd-devel] minimal required units

[Aaron_Wright at selinc.com]

Peter Sztan <sztanpet at gmail.com> wrote on 03/12/2015 09:33:38 AM:

> From: Peter Sztan <sztanpet at gmail.com>
> To: Aaron_Wright at selinc.com
> Cc: systemd Mailing List <systemd-devel at lists.freedesktop.org>
> Date: 03/12/2015 09:33 AM
> Subject: Re: [systemd-devel] minimal required units
> 
> Sorry for the noise, I have now read that you have already seen it.
> 

Just for illustration purposes, here are few units listed in 
systemd.special, that I don't feel like I need, but which I'm left 
wondering if systemd needs them:

cryptsetup.target
display-manager.service
getty.target
graphical.target
hibernate.target
hybrid-sleep.target
halt.target
initrd-fs.target
kbrequest.target
multi-user.target
network-online.target
poweroff.target
remote-fs.target
initrd-root-fs.target
runlevel*.target
sigpwr.target
sleep.target
suspend.target
swap.target

(and so on)

I can't tell from systemd.special if these are required or not.

> On Thu, Mar 12, 2015 at 5:32 PM, Peter Sztan <sztanpet at gmail.com> wrote:
> > man 7 systemd.special
> >
> > On Thu, Mar 12, 2015 at 4:41 PM,  <Aaron_Wright at selinc.com> wrote:
> >> Andrei Borzenkov <arvidjaar at gmail.com> wrote on 03/11/2015 08:47:43 
PM:
> >>
> >>> From: Andrei Borzenkov <arvidjaar at gmail.com>
> >>> To: Aaron_Wright at selinc.com
> >>> Cc: systemd-devel at lists.freedesktop.org
> >>> Date: 03/11/2015 08:47 PM
> >>> Subject: Re: [systemd-devel] minimal required units
> >>>
> >>> В Wed, 11 Mar 2015 12:02:29 -0700
> >>> Aaron_Wright at selinc.com пишет:
> >>>
> >>> > I'm trying to make an embedded device, and I would like to start 
with
> >>> > the
> >>> > minimal setup as possible. Are there some units that are required 
by
> >>> > systemd?
> >>> > I ask because systemd is complaining about a missing rescue.target 
unit,
> >>>
> >>> When does it do it?
> >>
> >> It was doing this because my default unit was not set correctly. But 
that
> >> isn't really the question. The question is, what units are required 
by
> >> systemd? How can I figure that out? It seems like rescue.target,
> >> local-fs.target, and local-fs-pre.target are required, but I've only
> >> discovered that after trial and error. I know the systemd.special man 
page
> >> lists a ton of special units, but it seems that not all of them are
> >> required. Right? Well, which ones are? I feel like I need to look 
through
> >> the code to see when a hardcoded unit is referenced, like 
> rescue.target was,
> >> that I don't know about.
> >>
> >> My device doesn't have many of the same requirements of a full 
desktop or
> >> server Linux, so I'm trying to strip out things from systemd, unit 
wise,
> >> that I don't want or need. I've customized sysinit.target and 
basic.target
> >> to just reference the units I want. And that seems to be going 
smooth, but
> >> it appears there are other units, that I didn't know about that are
> >> required, but that aren't documented as such (that I could find). 
This
> >> scares me a bit.
> >>
> >>>
> >>> > but I don't list rescue.target as a dependency of any other unit.
> >>> > However, grep tells me that /usr/lib/systemd/systemd contains the
> >>> > "rescue.target" string, which worries me. Is there a list of all 
the
> >>> > units
> >>> > that are required, even though no other unit lists them?
> >>
> >> _______________________________________________
> >> systemd-devel mailing list
> >> systemd-devel at lists.freedesktop.org
> >> http://lists.freedesktop.org/mailman/listinfo/systemd-devel
> >>

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