At irregular intervals, my screen goes dark for half a second

[Aragorn]

@gloewa

@Aragorn

@gloewa

The file dcdebugmask has read-only permission, even for the root user.

Some packagers do that because they don’t understand UNIX.

The root account has write access to everything, regardless of its permissions, as long as the filesystem itself is mounted writable.

 sudo sh -c 'echo 0x200 > /sys/module/amdgpu/parameters/dcdebugmask'                         ✔ 
[sudo] password for gloewa: 
sh: line 1: /sys/module/amdgpu/parameters/dcdebugmask: Permission denied

I did say “… as long as the filesystem itself is mounted writable.”

/sys is a virtual filesystem — its contents do not exist on your drive, but instead it is a filesystem-like representation of information exported by the kernel. As such, parts of /sys — parts which are themselves also virtual filesystems — are mounted read-only for reasons of stability and security.

For more information, please see this elaborate but informative tutorial…

• [Tutorial] Understanding and working with UNIX filesystems and permissions