RaspberryPi "is this a real kernel?"

[John Whitmore <arigead@gmail.com>]

I tried to subscribe to the RaspberryPi Kernel mailing list a few days ago but
I guess that my request has not been accepted as yet. Maybe it was missed so I
re-tried a moment ago. Since I can't get in there I thought I'd try
here. Apologies, bit of a panic.

So I'm trying to make a few changes to the Ubuntu Mate kernel for the
RaspberryPi V2. The Ubuntu kernel is 3.18.0-22 so I checked out, what I
thought was the last version of 3.18.0 from the RaspberryPi Kernel git repo,
did a make oldconfig, make menuconfig, to include CAN and stuff and then built
the kernel without any issues.

Now I'm not fully understanding the rest of the process but there's a utility
in the RaspberryPi tools to actually take the output from the build and
produce the image file for your SD card. It's questioning the integrity of my
built kernel and I've no idea why. (I think it's lovely and can't see why
anybody could question it!)

$ ./mkknlimg ../../linux/arch/arm/boot/zImage 3.18.0-can+.img
tail: +: invalid number of bytes
* Is this a valid kernel? In pass-through mode.


I'm using "mkknlimg" as the other utility "imagetool-uncompressed.py" is just
giving me a data file. 

So can anybody help me to understand what it is that's going wrong with this
process. 

John