Thanks for pointing out to Kernel Debug Stories – BUD17-TR04 link, I found it very useful.
In the document below point is mentioned under kdump/crash.
Note : that kdump for arm64 is still being upstreamed, expected in v4.12.
Full arm64 support in kexec-tools is also not yet landed.
But currently we are using v4.4, which means kdump will not work right?
Linux localhost 4.4.76-g766b8c0-dirty #5 SMP PREEMPT Fri Jul 14 12:23:57 IST 2017 aarch64