Comment 9 for bug 1489412

Hi everyone,

I've been doing quite a bit of testing on this matter. Following Paolo's your indications on 2) i didn't manage to be successful. I tried enabling the serial console and waited for a new network interface. Nothing that i can see, it seems that the board hangs at:
"Uncompressing Linux... done, booting the kernel."

Regarding your question, yes we are using this kernel (https://github.com/erlerobot/rpi2-kernel/blob/rpi-3.18.9-rt5/README.MD) with the PREEMPT_RT patches applied. Just compiled the kernel and copied the zImage to the boot partition and after a few changes on the kernel configuration i got to userspace. Here's the config that i'm using https://gist.github.com/vmayoral/881d3d63f1f2a08620ef.

At this point I could start comparing the two file systems (Debian and Snappy). When launching the binary described above (which corresponds with the APM autopilot that accesses several peripherals and also /dev/mem):
- Both images contain the same kernel: 3.18.9-rt5-v7+ #4 SMP PREEMPT RT
- Binaries have been launched in both file systems with superuser privileges
- Debian shows a responsive behavior, the autopilot works as expected
- Snappy works surprisingly slow

Tests in both file systems have been made under the same conditions. It doesn't seem to be related to communications. At this point we can discard that this issue is not related to the kernel.