“magic sysrq” in antiX runit

[Member seriousness]

Though I never experienced an XServer freeze in antiX, I’d like to have the possibility to do a clean shutdown/reboot, if it once happens. In kernel 4.9.0-279-antix.1-amd64-smp, magic sysrq is disabled by default. Creating /etc/sysctl.d/10-magic-sysrq.conf does not work. Is there a way to enable magic sysrq with runit or an alternative method to do a clean shutdown/reboot?

[Forum Admin anticapitalista]

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Warning
Magic SysRq should not be enabled in kernel for production or mission critical systems! Even if Magic SysRq is disabled at boot using for example sysctl, it still leaves /proc/sysrq-trigger open. Not to mention the fact that re-enabling SysRq is as easy as disabling it.

https://wiki.gentoo.org/wiki/Magic_SysRQ

Philosophers have interpreted the world in many ways; the point is to change it.

antiX with runit - leaner and meaner.

[Member seriousness]

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re-enabling SysRq is as easy as disabling it

but how, if /etc/sysctl.d/10-magic-sysrq.conf is not read and I’m not capable of building my own kernel?

[Member Xecure]

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@anticapitalista, I think there is a bug in /etc/runit-core/S13procps

Maybe at the end of the file, it should say:

case "$1" in
  start)
	do_start_cmd
  	;;
esac

@seriousness, could you try making the edit and restarting to see if /etc/sysctl.d/10-magic-sysrq.conf now loads properly?

• This reply was modified 1 year, 4 months ago by Xecure.

antiX Live system enthusiast.
General Live Boot Parameters for antiX.

[Forum Admin anticapitalista]

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@Xecure – the original procps (sysvinit) script doesn’t have it.

@seriousness – please post output of

ls -la /etc/rc*.d

Philosophers have interpreted the world in many ways; the point is to change it.

antiX with runit - leaner and meaner.

[Member seriousness]

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[Member Xecure]

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anticapitalista wrote:

@Xecure – the original procps (sysvinit) script doesn’t have it.

That is because the init script in sysvinit has this at the top

if [ true != "$INIT_D_SCRIPT_SOURCED" ] ; then
    set "$0" "$@"; INIT_D_SCRIPT_SOURCED=true . /lib/init/init-d-script
fi

so it runs the sourced script. On runit we need to add the extra code for the file to run do_start_cmd, me thinks. I will test it out in a bit on next reboot.

antiX Live system enthusiast.
General Live Boot Parameters for antiX.

[Member Xecure]

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Using “the fix” in antiX 21-runit, I get the correct swappiness

$ cat /proc/sys/vm/swappiness
10

which is configured in /etc/sysctl.conf

#added by antiX
vm.swappiness = 10

Using the original /etc/runit-core/S13procps, my swappiness is 60, meaning the /etc/sysctl.conf configuration was not loaded.

@seriousness, can you see if editing the file and adding the change proposed and rebooting activates the magic sysrq option?

antiX Live system enthusiast.
General Live Boot Parameters for antiX.

[Forum Admin anticapitalista]

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Thanks @Xecure – I’ll update the package with the fix.

Philosophers have interpreted the world in many ways; the point is to change it.

antiX with runit - leaner and meaner.

[Member ModdIt]

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Maybe good to add that those with the luxury of 4 or even 8GB memory and an SSD
might like to set swappiness to 1 or even 0.

Remembering that newer consumer SSD are write cycle optimised devices, samsung
speak for older ones lasted too long, hidden in marketing drivel was expectation
of 3 years before device replacement. My youngest computer is 12 years old.

[Member seriousness]

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Hey Xecure, I applied your fix and it works.

[Author]

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