PSA: Supervisor cannot report CPU temperature accurately on BeagleBone Black devices

[cywang117]

The Supervisor uses systeminformation currently to report device metrics including CPU temp. systeminformation reads from /sys/class/thermal for temperature readings. On the BeagleBone Black, both /sys/class/thermal and /sys/class/hwmon directories are empty, so it's not possible using software alone to read the CPU temp, unless the kernel is 3.8.x. This is a hardware manufacturer decision that the Supervisor cannot work around. See: https://forum.beagleboard.org/t/beaglebone-black-cpu-temperature/2183

Currently, the default CPU temp that's reported when no temperature can be read is null from systeminformation which is normalized to 0 on the dashboard. In older Supervisor versions running [email protected]. this value may be -1 which remains as -1 on the dashboard.