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systemd Disables the Linux Magic SysRq Key

posted by LaminatorX on Monday December 22 2014, @02:13AM   Printer-friendly
from the Man-what? dept.

An Anonymous Coward writes:

As long time SoylentNews community member Marand observed during some recent discussion of severe systemd boot problems, it turns out that systemd disables the magic SysRq key.

The magic SysReq key is described at Wikipedia as:

[...] a key combination understood by the Linux kernel, which allows the user to perform various low-level commands regardless of the system's state. It is often used to recover from freezes, or to reboot a computer without corrupting the filesystem.

A Fedora user who logged a bug report for this issue back in 2013 described the problem with systemd's unexpected and harmful default setting:

As systemd depends on many files on a rootfs, in case of any problems with rootfs, it is not able to do its basic function - control processes and (cleanly) shutdown/reboot when crtl-alt-del is pressed on local keyboard. As this is a feature, I'd like to ask to enable the sysrq by default on Fedora, otherwise it is not possible to reboot system even locally in case of emergency situation.

While that Fedora bug report is set to CLOSED NOTABUG, other Linux distros, like Mageia and Debian GNU/Linux, have restored the proper behavior.

Now that this problem has come to light, all Fedora users should evaluate whether or not they need to fix their systems to work around systemd's incorrect default setting. Users of other Linux distributions using systemd should also evaluate their systems, too, in case their distro has not yet fixed this unexpected bug.

 
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  • (Score: 1) by Wrong Turn Ahead on Monday December 22 2014, @04:53AM

    by Wrong Turn Ahead (3650) on Monday December 22 2014, @04:53AM (#128227)

    Regarding SysReq, it would seem that Debian fixed it, however, not with out a lot of resistance first. I think the comments in this bug report are quite telling...

    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=725422 [debian.org]

  • (Score: 2) by jbernardo on Monday December 22 2014, @05:48AM

    by jbernardo (300) on Monday December 22 2014, @05:48AM (#128236)

    In particular this one [debian.org] is particularly damning of the "nanny mentality" of systemd proponents:

    Also, this is a basic system setting, where it makes sense to change the kernel default by default, so it is natural that systemd does that. The goal of the systemd project is to take care of the basic system setup.

    I admit it is interesting that they finally admit the MCP goal, but I am not comfortable with it at all!

    • (Score: 0) by Anonymous Coward on Monday December 22 2014, @07:22AM

      by Anonymous Coward on Monday December 22 2014, @07:22AM (#128248)

      It goes beyond that. Systemd will eventually make every distro that use it as Poettering and his followers envision the one true distro to be. And that looks to be containerized OSX...