[Nix-dev] Modifying the init system (introducing S6supervisionsuite)

[Michael Raskin]

>On 2014-12-27 09:57, Michael Raskin wrote:
>>> I'm afraid I fail to see how S6 is better than systemd, except that the
>>> author is totally worried about the future of Linux with systemd.
>> 
>> S6 has logging without the unfixable bugs of JournalD
>> 
>> S6 doesn't insist on breaking xinit/startx-like functionality.
>> 
>> S6 doesn't barf if you put your swap into fstab.
>> 
>> SystemD has its unique WONTFIX bugs that no other init system shares
>> (sometimes not even UseLessD, although it is a minimalistic fork of
>> SystemD).
>> 
>> For me these bugs are showstoppers. I recently had a task at work that
>> was _much_ simpler by running 3 identical X servers.
>> 
>
>Please provide links to specific criticsms, bugs, etc. rather than just
>speaking in generalities.

These are not generalities.

https://bugs.freedesktop.org/show_bug.cgi?id=69934#c7
«
Yes. This means that the ancillary information like cgroup, commandline, etc., cannot be attached to the message. This is a known problem and doesn't explain why the message gets lost.
»

(The problem is: a service starts, drops privileges, finds a mistake in
configuration, reports the error and exits — JournalD files the log
message in an unexpected place).

>How does systemd "insist on breaking xinit/startx-like functionality",
>for instance? Are there open WONTFIX bugs on it? If so, please link.

http://lists.freedesktop.org/archives/systemd-devel/2012-February/004614.html
«
My recommendation would be to somehow patch your display manager to 
manage your screen only on request, rather then trying to avoid 
a display manager at all.
<…>
There's a fundamental contradiction in creating "forked off" sessions like
this: the whole audit system is written in a way that session ids can
only change from "unset" to "set" but not from "set" to "set to
something else".
»

(On NixOS, root running an X session from console gets a few EACES in 
strace output; on my system that uses only NixPkgs as package source, 
the same kernel etc. I can use openvt or manually launching X just fine
and I have some scripts copied from NixOS service definition and run
them via sudo).

>You haven't backed up "bart if you put your swap into fstab".

https://github.com/NixOS/nixpkgs/issues/5193
https://github.com/NixOS/nixpkgs/pull/5202

This hopefully will be fixed at some time in the future. For other 
problems, they are real problems for me and they seem to be by design.

>(And so on.)
>
>I don't particularly care whether you personally like or dislike
>systemd, but can we please at least keep critism founded on some sort of
>factual basis rather than just asserting things? (Links to bug reports,
>etc.)

If I want to assert things, I can say that journalctl reads hundreds of
megabytes to list the last 20 lines of logs and that cat reads the 
entire journal file faster (from HDD). 

I did check this fact multiple time, but apparently everyone who hit 
this already doesn't hope that SystemD can be fixed (they apparently 
check log signatures in a way that reads HDDs in a suboptimal order).

So no bug link here…