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sunrat

REISUB no more

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sunrat

This just popped up on a mailing list I follow. New recommendation is to use REIB (reboot even if broken) rather than REISUB. I think skinny elephants was always wrong too.

 

https://wiki.archlinux.org/index.php/Talk:Keyboard_shortcuts#Standard_shortcuts/Kernel:_Deprecation_of_the_long-standing_“REISUB”_mnemonic

 

https://lore.kernel.org/linux-doc/20190903160840.56652-1-kilobyte@angband.pl/T/

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abarbarian
10 hours ago, V.T. Eric Layton said:

http://www.brunolinux.com/01-First_Things_To_Know/Skinny_Elephants.html

 

In 15 years  (almost) of Slackware, I've never had to do this.

 

Never ever heard of this before. Found your link interesting and decided to try out the command given to check if you had th ekey enabled,

 

Quote

NOTE: For the skinny elephants to work you need to have the sysrq-key enabled in the kernel. (CONFIG_MAGIC_SYSRQ)
You can check if it is enabled by typing "cat /proc/sys/kernel/sysrq", if the command returns "1" the sysrq-key is enabled.
If it returns "0" you can enable it with "echo 1 > /proc/sys/kernel/sysrq"

 

so typed the command and got,

 

uKFkcO3.png

the NOTE don't say nowt ab'at "16" , so is me key enabled or not ? An does it matter ? 🤔

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sunrat
3 hours ago, abarbarian said:

the NOTE don't say nowt ab'at "16" , so is me key enabled or not ? An does it matter ? 🤔

 

16 means you only have sync enabled which is one of the commands now recommended not to use. If you do "echo 1 > /proc/sys/kernel/sysrq" you enable all sysreq commands. To only enable REIB as suggested, use 196 instead of 1 (I think).

More reading:

https://en.wikipedia.org/wiki/Magic_SysRq_key

https://linuxconfig.org/how-to-enable-all-sysrq-functions-on-linux

 

If you never used Magic SysReq keys, maybe you have a mythical perfect system, rarer than unicorn poo. Or you always hit the hardware reboot or shutdown buttons when your system freezes (not recommended).

If your system never freezes, you obviously don't abuse it enough, like I do. 😏

It has famously been said that any machine can be a smoke machine if you use it wrong enough. :D

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securitybreach
6 minutes ago, sunrat said:

If you never used Magic SysReq keys, maybe you have a mythical perfect system, rarer than unicorn poo. Or you always hit the hardware reboot or shutdown buttons when your system freezes (not recommended).

If your system never freezes, you obviously don't abuse it enough, like I do. 😏

It has famously been said that any machine can be a smoke machine if you use it wrong enough. :D

 

Well I have not had a system lock up in probably 10 years. I honestly forgot about REISUB and none of my keyboards even have the sysreq key as I use 60% mechanical keyboards.

 

Mine look like this

 

VAJPgGG.jpg

 

Granted, it does have 16 programmable layers but I only use a second layer for Function keys and things like insert, page up/down. I could map a sysreq button but haven't had a need in many years to do so.

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ebrke

OpenSUSE still has a setting in YaST that allows you to enable Magic SysReq keys. I haven't needed to use this process for years, but did use Skinny Elephants on more than one occasion without any terrible results. Back when I had KDE, my older hardware wasn't always up the the task at hand and would just freeze up.

Edited by ebrke

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sunrat

The reason I say RSEIUB (skinny elephants) was always wrong is it would sync (which I assume means write cached data to Disk) before ending running processes. And the logic I take to inspire the REIB recommendation, ie. without sync, is maybe we don't want to sync due to that cached data being corrupt in a freeze state. It may even have been the cause of that major filesystem corruption I had on my other SSD which I noted in another thread.

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abarbarian
22 hours ago, sunrat said:

 

16 means you only have sync enabled which is one of the commands now recommended not to use. If you do "echo 1 > /proc/sys/kernel/sysrq" you enable all sysreq commands. To only enable REIB as suggested, use 196 instead of 1 (I think).

More reading:

https://en.wikipedia.org/wiki/Magic_SysRq_key

https://linuxconfig.org/how-to-enable-all-sysrq-functions-on-linux

 

If you never used Magic SysReq keys, maybe you have a mythical perfect system, rarer than unicorn poo. Or you always hit the hardware reboot or shutdown buttons when your system freezes (not recommended).

If your system never freezes, you obviously don't abuse it enough, like I do. 😏

It has famously been said that any machine can be a smoke machine if you use it wrong enough. :D

 

8 hours ago, sunrat said:

The reason I say RSEIUB (skinny elephants) was always wrong is it would sync (which I assume means write cached data to Disk) before ending running processes. And the logic I take to inspire the REIB recommendation, ie. without sync, is maybe we don't want to sync due to that cached data being corrupt in a freeze state. It may even have been the cause of that major filesystem corruption I had on my other SSD which I noted in another thread.

 

Hmm all looks pretty complicated to me.

 

I have had some problems in the past but they usually end up with a black screen with loads of text.By using the key command Ctrl+Alt+F1  I can access a new text log in screen sometimes I have been able to follow the error warnings and have on a couple of occasions managed to fix the problem. Most of the time though I just try to use the shutdown button and if it fails to boot I just use a system backup and am up and running again in half an hour.

With the reasonable cost of hdd/ssd's these days and the speed of pc's it is easy and cost effective to just make and use backups of the system at least for the normal sort of home user.

 

😎

 

Besides someone once told me that crumbs in the floor keep elephants at bay. I got plenty of crumbs on the floor an no elephants so I guess that old wives tale does work. 😜

Edited by abarbarian
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sunrat
50 minutes ago, abarbarian said:

Hmm all looks pretty complicated to me.

 

Nah, simple as, bro. As we say here in Ozland.

System freezes and you can't get a TTY with Ctrl-Alt-Fx, Magic SysReq is the final solution. Hold Alt and SysReq (aka. PrintScreen) while consecutively pressing R, E, I, and B. It will reboot more safely than just pressing the reboot or shutdown hardware button. As long as the keyboard is not also frozen of course.

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abarbarian
1 hour ago, sunrat said:

 

Nah, simple as, bro. As we say here in Ozland.

System freezes and you can't get a TTY with Ctrl-Alt-Fx, Magic SysReq is the final solution. Hold Alt and SysReq (aka. PrintScreen) while consecutively pressing R, E, I, and B. It will reboot more safely than just pressing the reboot or shutdown hardware button. As long as the keyboard is not also frozen of course.

 

I don't doubt that the REIB works well and would be a neat extra way to reboot in dire circumstances. However the Ubuntu based guide does not cover EFI systems and I can not find the /boot files they mention and the wiki is no help to me at least. For now I will leave well alone and live with being a 16 whatever that is. I may look into this at some other time. 😎

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securitybreach

That's kind of odd considering that EFI have been around for well over a decade.

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abarbarian
2 hours ago, securitybreach said:

That's kind of odd considering that EFI have been around for well over a decade.

 

The Ubuntu guide linked to asks for the file "config-4.13.0-25-generic",

,

 

$ ls /boot
abi-4.13.0-25-generic     initrd.img-4.13.0-25-generic  memtest86+_multiboot.bin
config-4.13.0-25-generic  memtest86+.bin                System.map-4.13.0-25-generic
grub                      memtest86+.elf                vmlinuz-4.13.0-25-generic

 

and I don't have similar in my /boot,

 

$ ls /boot
EFI                           initramfs-linux.img  refind_linux.conf
initramfs-linux-fallback.img  intel-ucode.img      vmlinuz-linux

I could try to find similar on my / btu as I am busy with other things I'll leave as is for the moment. Always nice to find out more about the penguins inner workings though. 😎

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sunrat

I don't get what Ubuntu or /boot or EFI has to do with it. The relevant file is /proc/sys/kernel/sysrq which I think is the same across all Linuxii.

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securitybreach
1 minute ago, sunrat said:

I don't get what Ubuntu or /boot has to do with it. The relevant file is /proc/sys/kernel/sysrq which I think is the same across all Linuxii.

 

Yup, /proc/sys/kernel/sysrq is the same on all linux distros.

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V.T. Eric Layton
2 hours ago, sunrat said:

Linuxii???

 

Is that the Latin-ized plural conjugation of the word?

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sunrat
2 hours ago, V.T. Eric Layton said:

 

Is that the Latin-ized plural conjugation of the word?

 

Yes of course. ;)

Years ago you called me RattusSolarus in jest and I now use that as my handle in some places. It's my IGN in Ingress. 🤓  Strictly though it should be RattusSolaris. But I don't know any Latin speakers to give me grief over it.

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V.T. Eric Layton

Well, if there were more of you, I'd refer to the group as RattusSolarii. ;)

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Hedon James
3 hours ago, V.T. Eric Layton said:

Well, if there were more of you, I'd refer to the group as RattusSolarii. ;)

 

I too am a sunrat....i'm just not THE sunrat!  does that count?  😜

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V.T. Eric Layton

If I'm any kind of rattus, it's rattus nocturnus. Born, raised, still live in Florida... was NEVER a sun-worshiper. The night time is the right time for this rat. ;)

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