I builded my code in a ubuntu virtual box and tried then to upload it via terminal. I always get rebooting messages continously and tried then to upload it via Qgroundcontrol. I receive then “Error: Sync: Send Command: Invalid sync response: 0xfe 0x3e” and after a few milliseconds the booting process of Pixhawk continues. So at least I know, that Pixhawk is recognized in my virtual machine.
On my windows 10 host it would be possible to upload my firmware, but since the builded firmware contains some symbolic links and references, my workaround to copy paste the files to a shared folder or USB would not work. Do you know, what I am missing with virtual box? I couldn’t find a solution using google