[meta-xilinx] xilinx 4.4 -> 4.6 kernel doesn't boot

[Arno Steffens]

Keeping my previous system (yocto 2.1 uboot) I try to boot into recent yocto2.2 (xilinx 4.6) kernel.
It doesn't, last message is "Starting kernel ..."

I read that this has usually 2 reasons, mismatching bootcmd or MachineID.

I try to boot (working 4.4 kernel) with other machine id by setting in uboot
"set machid 44".
Although uboot confirmes this by :
Using machid 0x44 from environment
it boots. So I guess this might not the problem.

Found that indeed in devicetree something has been changed:

-		bootargs = "console=ttyPS0,115200 earlyprintk";
+		bootargs = "";
+		stdout-path = "serial0:115200n8";

So I changed this in my linux dts file, but result keeps same.
I also try to modify my previous bootargs:

console=ttyPS0,115200 earlyprintk root=/dev/nfs nfsroot...

and omit the console and earlyprintk without an effect.

How can I debug this?

Best regards
Arno