Privilege problem of device files on de10-nano board

[marktwtn]

Executing the PoW on de10-nano board needs to open or do the operation to the following device files

• /dev/cpow-ctrl
• /dev/cpow-idata
• /dev/cpow-odata
• /dev/mem

The first three device files appears after installing the specific kernel module.
The last device file is physical memory.

Since the previous arm image from LampaLab uses root as logging account, everything went well.
However, when it comes to the new armhf image, the image uses normal user logging account.
Hence it has some problems since the operation to /dev/mem is only allowed when using root account or using sudo command.
Even if I changed the file privilege, it did not help.

Goal:

• buildkite CI can build dcurl and execute PoW with FPGA
• Ansible Playbook can activate the remote worker of multiple de10-nano boards easily

[marktwtn]

We can set the user account of the buildkite agent as root.
Since the buildkite agent is managed with systemd, the user account can be changed by modifying the service user configuration /lib/systemd/system/buildkite-agent.service.

[marktwtn]

Since Ansible Playbook also uses systemd to manage the remote worker, it would not be a problem to set it as root account.