From: "Michał Górny" <mgorny@gentoo.org>
To: gentoo-dev@lists.gentoo.org
Cc: lu_zero@gentoo.org
Subject: Re: [gentoo-dev] eselect init
Date: Sun, 26 May 2013 14:08:34 +0200 [thread overview]
Message-ID: <20130526140834.0e19ede5@gentoo.org> (raw)
In-Reply-To: <51A1F493.90101@gentoo.org>
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On Sun, 26 May 2013 13:40:03 +0200
Luca Barbato <lu_zero@gentoo.org> wrote:
> On 5/26/13 12:57 PM, Michał Górny wrote:
> > Switch inittab? Now you added really dangerous behavior to the wrapper
> > code. I can hardly even express this in words.
>
> I need it for my purpose, bb-init syntax isn't the same as sysv.
Then you need to use a different file. Feel free to rename either
inittab but don't even think of switching files like this.
> > You are telling me that a wrapper, a thing that gets executed *every*
> > boot needs to do some random magic to know which init system was in use
> > and which one is supposed to be in use, and then conditionally move
> > around configuration files necessary for it to run. This is just
> > *INSANE*.
>
> I like to think it normal and the wrapper doesn't need to run every time
> but only when a switch had been requested. And only if you prefer doing
> the switch at boot time instead than at shutdown.
Well, that makes it a bit less destructive. Though I still don't like
the idea.
> > And what will happen if moving the files fail? What if half of
> > configuration belongs to old init, and half to new? And it all happens
> > automagically on boot, on an incomplete system without any console
> > started, without Internet connection established and without any
> > serious mean of help.
>
> You can:
>
> - consider rolling back
> - drop to a shell
>
> Nothing so terrible.
Sounds like an initramfs...
> > What I'm telling is: if user uses A as init system (and wanted to switch
> > to B), last thing he'd expect is C being started. Configuration for
> > OpenRC may be long unmaintained, may start services which are not
> > supposed to be started anymore and so on.
>
> The safest would be dropping to a shell in your scenario.
>
> As I stated from start the "switch on boot" would work so the wrapper
> checks a switch had been requested, it knows the current init, that must
> work since worked the previous boot, the next init, that supposedly
> should work, does the pivoting, shuffling and such and the next boot it
> just hands over to the current init.
It all depends on how it is implemented. If we decide not to
touch /sbin/init, then sysvinit will be the effective fallback at some
earlier or later point, depending on what will fail. This is what I
really dislike.
> > We're not talking about percentages here. A *single* fragile script is
> > enough to cause trouble. Ten good ones won't revert it.
>
> A single fragile script can be fixed I guess, which is the one you have
> in mind that is concerning?
You could've asked me that when I was still using OpenRC. I don't
really want to grep the 40 scripts right now, and I don't think I have
the worse cases installed here.
> > What are you talking about now? I was just saying that *if* you
> > link /sbin/init to systemd, and you're running sysvinit, 'init foo'
> > will be passed through to telinit.
> >
> > But now I see that I was wrong and it actually happened when
> > 'systemctl' was symlinked to 'init'. Nevermind then.
> >
> > In any case, keeping all the tools like 'telinit' should be *enough* to
> > keep the current init running and rebooting.
>
> You are focused on systemd, I'm focused on bb-init among the rest, it
> uses a different syntax for the inittab, so if you want to switch from
> one or another you either prepare a least-action script that switch the
> inittab on reboot or a first-action script that does that on boot.
>
> For your needs probably just pivoting a symlink should work almost fine,
> as long your stay sysvinit compatible, yet doing that as early init or
> as post kill-all should work better even in your case.
Well, you're transforming a simple idea with potentially relatively
wide audience into a horror story with a single user.
--
Best regards,
Michał Górny
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next prev parent reply other threads:[~2013-05-26 12:08 UTC|newest]
Thread overview: 139+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-25 9:54 [gentoo-dev] eselect init Luca Barbato
2013-05-25 10:25 ` Peter Stuge
2013-05-25 11:57 ` Tom Wijsman
2013-05-26 1:52 ` Walter Dnes
2013-05-26 8:50 ` Tom Wijsman
2013-05-26 2:02 ` Peter Stuge
2013-05-26 8:56 ` Tom Wijsman
2013-05-25 19:08 ` Matthew Thode
2013-05-26 14:13 ` Ian Stakenvicius
2013-05-26 23:54 ` Luca Barbato
2013-05-25 11:13 ` Pacho Ramos
2013-05-25 12:03 ` Tom Wijsman
2013-05-25 12:25 ` Pacho Ramos
2013-05-25 15:42 ` Luca Barbato
2013-05-25 11:29 ` Sergei Trofimovich
2013-05-25 12:12 ` Tom Wijsman
2013-05-25 13:15 ` Luca Barbato
2013-05-25 17:35 ` Sergei Trofimovich
2013-05-25 19:49 ` Chí-Thanh Christopher Nguyễn
2013-05-25 12:13 ` hasufell
2013-05-25 15:51 ` Luca Barbato
2013-05-25 13:38 ` Tom Wijsman
2013-05-25 19:09 ` J. Roeleveld
2013-05-25 19:55 ` Tom Wijsman
2013-05-25 20:07 ` Alex Xu
2013-05-25 20:59 ` Tom Wijsman
2013-05-26 12:59 ` J. Roeleveld
2013-05-26 13:58 ` Tom Wijsman
2013-05-26 14:54 ` Ian Stakenvicius
2013-05-26 13:15 ` Michał Górny
2013-05-26 14:07 ` Tom Wijsman
2013-05-26 14:44 ` Rich Freeman
2013-05-26 6:43 ` Michał Górny
2013-05-26 8:58 ` Robert David
2013-05-26 9:20 ` Michał Górny
2013-05-26 9:32 ` Robert David
2013-05-26 9:45 ` Tom Wijsman
2013-05-26 10:09 ` Michał Górny
2013-05-26 11:45 ` Tom Wijsman
2013-05-26 12:01 ` Michał Górny
2013-05-26 9:21 ` Tom Wijsman
2013-05-26 10:01 ` Robert David
2013-05-26 10:11 ` Rich Freeman
2013-05-26 10:18 ` Chí-Thanh Christopher Nguyễn
2013-05-26 11:28 ` hasufell
2013-05-26 12:10 ` Tom Wijsman
2013-05-26 9:55 ` Luca Barbato
2013-05-26 10:39 ` Tom Wijsman
2013-05-26 10:57 ` Michał Górny
2013-05-26 11:40 ` Luca Barbato
2013-05-26 12:08 ` Michał Górny [this message]
2013-05-26 12:24 ` Luca Barbato
2013-05-26 14:58 ` Ian Stakenvicius
2013-05-27 10:36 ` [gentoo-dev] Switchup-mode and boottime selector? Was: " Duncan
2013-05-27 20:26 ` Alex Xu
2013-05-27 22:40 ` Walter Dnes
2013-05-28 9:56 ` [gentoo-dev] " Duncan
2013-05-28 11:56 ` Tom Wijsman
2013-05-29 0:36 ` Duncan
2013-05-29 8:52 ` Tom Wijsman
2013-05-29 18:15 ` Walter Dnes
2013-05-29 19:56 ` Tom Wijsman
2013-05-29 20:55 ` William Hubbs
2013-05-30 0:06 ` Tom Wijsman
2013-05-30 0:22 ` William Hubbs
2013-05-30 1:36 ` Duncan
2013-05-30 6:35 ` Tom Wijsman
2013-05-30 20:41 ` William Hubbs
2013-05-30 6:46 ` Ciaran McCreesh
2013-05-30 13:54 ` Ian Stakenvicius
2013-05-31 6:21 ` Ciaran McCreesh
2013-05-30 6:30 ` Luca Barbato
2013-06-22 19:35 ` Markos Chandras
2013-05-30 2:52 ` Walter Dnes
2013-05-30 6:19 ` Tom Wijsman
2013-05-30 6:36 ` Dale
2013-05-30 6:31 ` Ciaran McCreesh
2013-05-28 3:55 ` [gentoo-dev] " Luca Barbato
2013-05-28 4:19 ` Michał Górny
2013-05-28 4:43 ` Luca Barbato
2013-05-28 12:15 ` Ian Stakenvicius
2013-05-28 12:15 ` Ian Stakenvicius
2013-05-26 11:58 ` Tom Wijsman
2013-05-26 14:52 ` Luca Barbato
2013-05-26 15:39 ` Tom Wijsman
2013-05-26 16:41 ` William Hubbs
2013-05-26 16:48 ` William Hubbs
2013-05-26 16:55 ` Michał Górny
2013-05-26 22:58 ` William Hubbs
2013-05-26 23:47 ` Luca Barbato
2013-05-27 23:45 ` [gentoo-dev] Separate boot/root already [WAS: eselect init] Walter Dnes
2013-05-28 15:07 ` Luca Barbato
2013-06-01 9:23 ` [gentoo-dev] Re: eselect init Steven J. Long
2013-06-01 11:43 ` Steven J. Long
2013-06-02 9:15 ` Luca Barbato
2013-06-02 18:20 ` [gentoo-dev] " Steven J. Long
2013-06-02 18:48 ` Fabio Erculiani
2013-06-08 13:37 ` [gentoo-dev] " Steven J. Long
2013-06-02 22:35 ` [gentoo-dev] " Luca Barbato
2013-06-03 0:37 ` Walter Dnes
2013-06-03 0:57 ` Rich Freeman
2013-06-03 7:03 ` Tom Wijsman
2013-06-03 9:42 ` Luca Barbato
2013-06-03 6:19 ` [gentoo-dev] " Duncan
2013-06-03 6:26 ` [gentoo-dev] " Pacho Ramos
2013-06-04 18:55 ` William Hubbs
2013-06-04 19:09 ` Rich Freeman
2013-06-08 13:28 ` [gentoo-dev] " Steven J. Long
2013-06-20 10:16 ` [gentoo-dev] " Fabio Erculiani
2013-06-20 17:10 ` [gentoo-dev] " Steven J. Long
2013-06-20 20:48 ` William Hubbs
2013-06-25 4:53 ` [gentoo-dev] " Steven J. Long
2013-06-20 20:56 ` [gentoo-dev] " William Hubbs
2013-06-21 2:39 ` Michał Górny
2013-06-21 4:16 ` William Hubbs
2013-06-21 10:23 ` Michał Górny
2013-06-21 15:16 ` William Hubbs
2013-06-21 15:23 ` Fabio Erculiani
2013-06-21 16:42 ` William Hubbs
2013-06-22 11:23 ` Jason A. Donenfeld
2013-06-22 11:57 ` hasufell
2013-06-21 19:34 ` Luca Barbato
2013-06-22 1:27 ` Ulrich Mueller
2013-06-22 1:48 ` Michael Weber
2013-06-21 15:29 ` Michał Górny
2013-06-21 16:13 ` Markos Chandras
2013-06-21 16:50 ` William Hubbs
2013-06-21 19:36 ` Luca Barbato
2013-06-21 10:30 ` Michael Weber
2013-06-21 11:19 ` Fabio Erculiani
2013-06-21 11:26 ` Pacho Ramos
2013-06-21 11:50 ` Luca Barbato
2013-06-21 14:36 ` William Hubbs
2013-06-21 15:48 ` Pacho Ramos
2013-06-22 6:59 ` [gentoo-dev] " Duncan
2013-06-22 10:07 ` Pacho Ramos
2013-06-22 11:13 ` Michael Weber
2013-06-22 11:26 ` Rich Freeman
2013-06-22 17:05 ` Luca Barbato
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