Crashkernel not starting after crash

I am trying to start a crash kernel using Linux's Kernel Crash Dump. Both of the host and crash kernel are compiled linux-4.13.16 kernel. Unfortunately, the crash kernel fails to start after the crash occurs. iomem reports reserved space for crash kernel and kdump reports its ready for kdump: > 28000000-37ffffff : Crash kernel $ sudo kdump-config show DUMP_MODE: kdump USE_KDUMP: 1 KDUMP_SYSCTL: kernel.panic_on_oops=1 KDUMP_COREDIR: /var/crash crashkernel addr: 0x28000000 /var/lib/kdump/vmlinuz: symbolic link to /boot/vmlinuz-4.13.16ksa kdump initrd: /var/lib/kdump/initrd.img: symbolic link to /var/lib/kdump/initrd.img-4.13.16ksa current state: ready to kdump kexec command: /sbin/kexec -p --command-line="BOOT_IMAGE=/boot/vmlinuz-4.13.16ksa root=UUID=3254c608-d885-4dfc-b20b-fa4e69564dca ro quiet splash vt.handoff=7 irqpoll noirqdistrib nr_cpus=1 nousb systemd.unit=kdump-tools.service" --initrd=/var/lib/kdump/initrd.img /var/lib/kdump/vmlinuz $ cat /proc/cmdline BOOT_IMAGE=/boot/vmlinuz-4.13.16ksa root=UUID=3254c608-d885-4dfc-b20b-fa4e69564dca ro quiet splash crashkernel=384M-2G:128M,2G-:256M vt.handoff=7 After triggering crash using sysrq-trigger, it doesn't load crash kernel. I have tested with a generic kernel, linux-4.8.0-36-generic, which successfully works. Syslog file are here . Both linux-4.8.0-36-generic and linux-4.13.16ksa has same .config file. Only difference I can see is that during boot, for linux-4.13.0-38, it loads the efi.signed vmlinuz(vmlinuz-4.13.0-38-generic.efi.signed) where as the compiled linux-4.13.16ksa is not efi signed. Can it be an issue? How can I resolve this?