[Solved] When running as root produces a 'you need to run as root' message

1

I’m in the process of re-writing a project… and somewhere down the line something has gone astray. This uses the same initialisation code, a single line to write some text and the same hardware as the working executable.

However I’m getting this message when running as root and with the setcap recommendation in place.

Very confusing to get a ‘you need to run as root’ message when you’re the binary as root!
Has anyone seen this before?
All pointers welcome!

Message is:

Can’t set realtime thread priority=99: Operation not permitted.
You are probably not running as root ?
This will seriously mess with color stability and flicker
of the matrix. Please run as root (e.g. by invoking this
program with sudo), or setting the capability on this
binary by calling
sudo setcap ‘cap_sys_nice=eip’ /home/display/Matrix_Driver/matrix_test

2

It’s funny how you work on a problem for ages… then post about it… and immediately fix it!

The issue here was my matrix-initialisation code was getting called twice.

Sharing so others don’t fall foul of this.