I can't seem to get kdump working with the 4.11 kernel.

I actually have the same issue on another platform with a vanilla 4.11.1.

I'm running kernel-default-4.11.0-1.1.x86_64 with this cmdline, set up using
defaults with yast2 kdump:

BOOT_IMAGE=/boot/vmlinuz-4.11.0-1-default
root=UUID=dd6a8147-d379-47cd-b339-d3883b1fe011 resume=/dev/sda2 splash=silent
quiet showopts crashkernel=135M,high crashkernel=72M,low

Here is what dmesg reports regarding the reservation:

[    0.000000] Reserving 72MB of low memory at 2896MB for crashkernel (System
low RAM: 3272MB)
[    0.000000] Reserving 135MB of memory at 33120MB for crashkernel (System
RAM: 32438MB)

The kdump service is in failed state, and if I run the script manually, I get
this:

jamesoakley:~ # /lib/kdump/load.sh
ELF core (kcore) parse failed
Cannot load /boot/vmlinuz-4.11.0-1-default

Looking at the kexec-tools code, it appears that there a few situations that
can cause that parse failed message, where it simply returns -1 with no other
indication.