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Old 11-17-2014, 08:47 AM   #1
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Registered: Sep 2014
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Difference between kdb kdump and SysRq kdump


I have a custom linux kernel version 2.6.32 running as a VM on Hyper-V 2008 R2 with 2vCPUs.

When I am triggering kdump using the magic sysrq (sh#echo c > /proc/sysrq-trigger), the VM gets rebooted in the middle of starting the capture kernel. This happens intermittently with no reason for the reboot. The Windows eventlog shows it is a CPU triple fault issue.

But, when I trigger kdump after entering in to kernel kdb mode (kdb#kdump), kdump is working successfully for multiple times.

My kdump commandline is 
Kernel command line: root=/dev/ram0 nmi_watchdog=0 irqpoll maxcpus=1 reset_devices no_timer_check debug  ata_piix.prefer_ms_hyperv=0 console=ttyS0,9600n8 ip=none
So, what is the difference between the two methods? Is there any interrupt which is not properly handle in sysrq kdump ?
Please explain ?

Thanks in advance,
Old 11-26-2014, 08:05 AM   #2
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Registered: Sep 2014
Location: India
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Hello experts,

Could someone answer this?



hyper-v, kdump, magicsysrq

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