Ready to try dependency based boot sequencing?
Frans Pop
elendil at planet.nl
Wed Feb 6 19:56:24 UTC 2008
On Wednesday 06 February 2008, Frans Pop wrote:
> This is a resend (with some changes) of a mail earlier sent to Petter
> privately. Contents seem useful for others too.
And here are the most relevant bits of Petter's reply.
(Note: I'm not subscribed to this list.)
---------- Forwarded Message ----------
[Frans Pop]
> However, it does IMO make sense for anacron and cron to be stopped very
> early in the sequence as you don't really want them starting anymore when
a
> shutdown has been initiated. The fact that insserv moves them so far down
> could be considered a regression.
I agree, but it is a bug that need to be fixed in the cron and anacron
packages. They need to have $remote_fs listed in their required-stop
header.
> Below a complete overview of the changes in runlevels (script attached).
> For levels S, 0 and 6 I have not distinguised between K and S scripts (as
> insserv changes all of them into S scripts, but for the others the
> distinction is kept.
>
> A problem I see is that in some levels scripts have been _added_ that were
> not executed at that level before (no number in the second column).
> Examples are:
> - console-screen.sh (0, 1, 6)
> - ssh (0, 6)
> - pppd-dns (0, 1, 6)
> - hwclockfirst.sh (0, 6)
Hm, strange. If the scripts are already installed, insserv should not
add them to any runlevels. I will have to investigate these. I note
that at least console-screen.sh list the runlevels 0, 1 and 6 in its
default-stop header, whihch I guess is wrong.
> The last means that on reboot/shutdown the hardware clock will now be
> updated twice instead of once, thus _slowing_ the shotdown process...
Yes. I will try to reproduce this issue in the test suite, to make
sure I get rid of it permanently.
> Basically I feel that every case where a script that moves more than
> a couple of places up or down should be investigated. In a lot of
> cases it will probably not be a real issue or even a real
> improvement. In other cases it may need fixing.
I agree. And as far as I have investigated, it is bugs in the
dependencies of the affected scripts, or actually correct.
Addressing those which moved more than 5 steps.
> Runlevel S
[...]
> pcmciautils 6 27 -21
This is a bug in the script. The script got a header, but is missing all
dependencies.
> procps 7 19 -12
This is correct. procps can and should run as soon as /proc is mounted.
> udev-mtab 17 22 -5
This is correct. updating mtab can be done as soon as / is mounted
read-write.
> alsa-utils 24 34 -10
This is a bug in the dependencies. It should depend on $remote_fs,
not $local_fs.
> hwclock.sh 25 11 14
I believe this is correct.
> lm-sensors 27 32 -5
Not sure.
> urandom 29 36 -7
This is correct. urandom can run as soon as /var/ is mounted by
mountall.sh.
I will have to look at the other runlevels later.
Happy hacking,
--
Petter Reinholdtsen
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