Linux on iMac reboots instead of shutdown

[Oldhabbits]

No solutions found thus far, still using the power switch…
cheers,
Eddy

 

[APTI]

I have seen issues periodically on fedora that causes the inability to restart and also to cause restart instead of shutdown. The problem is indeed ACPI related and has to be fixed in the kernel with an update. Which may never come if it is not a known reported bug.
The problem when I see it seems to come from the watchdog which is meant to reboot the system if it is locked up or experiences a severe problem. So the watchdog is most likely the culprit here.
what follows is my notes on this.

================ nmi watchdog ====================================

cat /proc/sys/kernel/nmi_watchdog ---- shows status, 1= on 0= off
sudo sysctl kernel.nmi_watchdog=x ---- replace x with 1 or 0, changes value til restart which will allow you to test if this is the issue

/etc/sysctl.conf enter line kernel.nmi_watchdog=x --- makes it permanent. Default is on

 

[Oldhabbits]

================ nmi watchdog ====================================

cat /proc/sys/kernel/nmi_watchdog ---- shows status, 1= on 0= off
sudo sysctl kernel.nmi_watchdog=x ---- replace x with 1 or 0, changes value til restart which will allow you to test if this is the issue

/etc/sysctl.conf enter line kernel.nmi_watchdog=x --- makes it permanent. Default is on

Just tried your idea, but it has no effect on my imac 2016. Still needed the power button as usual… Thanks anyway !
Cheers,
Eddy

 

[Patou]

Hi!

Just wanted to let everyone know that I just submitted a bug report for this problem on the Linux Kernel Bugzilla:

219185 – System reboots after shutdown or sleep

If anyone is interested in helping with feedback and testing, feel free to do so.

Hope for the best!

 

[Oldhabbits]

I have the same problem with my imac, only in macos or windows it will shutdown properly…

Long ago, I read an article about this. It is an certain register in the cpu that should receive an impuls to shutdown completly. Macos does that, Windows too but our linux kernel does not. Apple did not connect a certain cpu pin on their motherbords, needed for sending that signal like Intel had foreseen this for other motherbords. Apple’s macos is sending an other instructionset to accomplish the same effect, but Linux can not do the same thing to keep itself compatible with other brands of computers.
But now you know why we have to press that button !

Greetz, Eddy

 

[mrcrossroads]

Side question: To anyone who would know, is this a typical problem for iMacs? I have a 2013 iMac desktop coming available to me sometime in the near future, and this would be good to know.

I had Mint running on a 2013 iMac and didn't have the issue.

 

[Trenix25]

You might try using /usr/sbin/poweroff which is a symlink to /usr/bin/systemctl. When called as poweroff it should shut down the system and leave it that way. I either use poweroff or reboot.

Signed,

Matthew Campbell

 

[bmc5311]

Resurrecting this thread -
I have an iMac 16,2 with Debian 12 installed (not dual booted, Debian only). The problem described by the OP still exists, current kernel is 6.1.0-12-amd64. Anyone ever solve this?

Edited: changed 16,1 to 16,2 original post was a typo.

Replying to myself...
Just switched from Debian 12 to Fedora 41, original issue persists, additionally the sound issue persists as well.

 

[bmc5311]

You might try using /usr/sbin/poweroff which is a symlink to /usr/bin/systemctl. When called as poweroff it should shut down the system and leave it that way. I either use poweroff or reboot.

Signed,

Matthew Campbell

Tried "/usr/sbin/poweroff" - issue persists. Thanks for the recommendation.

 

[Condobloke]

@bmc5311 ....you would do so much better by opening your own thread !.......this thread dates back to 2022 and the Opening Poster has not been seen since then. No answer has been found, possibly because the thread is a disjointed mess.