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== Comment: #0 - Praveen K. Pandey <praveen.pan...@in.ibm.com> - 2018-09-19 
04:49:39 ==
---Problem Description---
 [Witherspoon-DD2.2][Ubu 18.10] [4.18.0-7-generic ] : Sysrq trigger disabled 
when writing to /proc/sysrq-trigger 

while  testing kdump trying trigger kdump panic via /proc/sysrq-trigger it 
failed as : SysRq : This sysrq operation is disabled
LOG:

root@test:~# cat /proc/sys/kernel/sysrq 
176
root@test:~# echo c > /proc/sysrq-trigger
root@test:~# dmesg
[  380.340051] mlx5_core 0000:01:00.1 enp1s0f1: Self test out: status flags(0x2)
[  389.404239] sysrq: SysRq : This sysrq operation is disabled.
root@test~# cat /boot/config-4.18.0-7-generic | grep CONFIG_MAGIC_SYSRQ
CONFIG_MAGIC_SYSRQ=y
CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE=0x01b6
CONFIG_MAGIC_SYSRQ_SERIAL=y
root@test:~# cat /etc/sysctl.conf | grep kernel.sysrq
#kernel.sysrq=438
root@test:~# kdump-config show
DUMP_MODE:        kdump
USE_KDUMP:        1
KDUMP_SYSCTL:     kernel.panic_on_oops=1
KDUMP_COREDIR:    /var/crash
crashkernel addr: 
   /var/lib/kdump/vmlinuz: symbolic link to /boot/vmlinux-4.18.0-7-generic
kdump initrd: 
   /var/lib/kdump/initrd.img: symbolic link to 
/var/lib/kdump/initrd.img-4.18.0-7-generic
current state:    ready to kdump

kexec command:
  /sbin/kexec -p --command-line="root=UUID=c0302064-c5a3-49a7-8bd4-402283e6fcbe 
ro quiet splash nr_cpus=1 systemd.unit=kdump-tools.service irqpoll noirqdistrib 
nousb" --initrd=/var/lib/kdump/initrd.img /var/lib/kdump/vmlinuz
root@test:~# 

Regards
Praveen

== Comment: #2 - Praveen K. Pandey <praveen.pan...@in.ibm.com> - 2018-09-19 
05:16:11 ==
when i enable  in /etc/sysctl.conf it works  . i append below value in  
sysctl.conf

echo "kernel.sysrq = 1" >> /etc/sysctl.conf

I think this is should be enable by default  in ubuntu 18.10 as earlier
ubuntu distro it has , not sure why it got removed as kdump mechanism
require this .

Praveen
Regards

** Affects: linux (Ubuntu)
     Importance: Undecided
     Assignee: Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage)
         Status: New


** Tags: architecture-ppc64le bugnameltc-171577 severity-medium 
targetmilestone-inin1810
-- 
Ubuntu18.10:Witherspoon:DD2.2 - Sysrq trigger disabled when writing to 
/proc/sysrq-trigger
https://bugs.launchpad.net/bugs/1793369
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