A bit of background first - I'm trying to configure a MicroBlaze Linux (big-endian version) system on a Xilinx ML506 eval board. The goal is to use the second partition of a CompactFlash card attached to the Xilinx SystemACE controller. So far, root in initramfs works and after boot, I can mount and use said partition, no problem.

But if I try to use it right from the getgo with the "root=/dev/xsa2" kernel command line parameter, the system hangs with

[...]
Freeing unused kernel memory: 143k freed
Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004

And that's it - no regdump, no call trace, no further nothing from the serial console, even though kernel has been configured with debugging enabled. Now, I'm pretty new at this, so is there something else I should be doing to see something more informative from the kernel?