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Thread: [14.10] How to enable full KREISUB

  1. #1
    Join Date
    Nov 2014

    [14.10] How to enable full KREISUB

    I have a bit of an issue. Sometimes my computer freezes (darn MESA drivers not working on up to date graphic cards) and the only way to reboot safely is Alt-SysRq-SUB... Because K, R, E, and I are disabled. How does one enable them?

  2. #2
    Join Date
    Aug 2014
    Ubuntu 16.04 Xenial Xerus

    Re: [14.10] How to enable full KREISUB

    Apparently it's disabled because of security issues.
    This is from the file /etc/sysctl.d/10-magic-sysrq.conf where you can re-enable.
    # In general, the magic SysRq key is not needed for the average Ubuntu
    # system, and having it enabled by default can lead to security issues on
    # the console such as being able to dump memory or to kill arbitrary
    # processes including the running screen lock.
    gksudo gedit /etc/sysctl.d/10-magic-sysrq.conf
    and change the last line to...
    kernel.sysrq = 1

    You can see if working by switching to a tty ctrl+alt+F1 and using reisub
    Security issue is your decision.

    PS Many people think you need to hold down all three keys...ctrl+alt+SysReq and enter reisub
    You only need to hold down ctrl+alt, press and release SysReq then enter reisub while still holding down ctrl+alt
    Last edited by CantankRus; November 13th, 2014 at 04:26 AM.


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