Feature request, but must be universallly accepted by ALL blanker authors

Vladimir Dergachev volodya at mindspring.com
Sat Oct 3 04:39:27 UTC 2020

On Fri, 2 Oct 2020, Gene Heskett wrote:

> Greetings x-people;
> The LinuxCNC people have just brought it up from Debian wheezy to buster
> for a base install.
> But the security paranoia is going to get someone maimed or killed.
> Someone has decreed that the screen blanker must be subject to a new
> login before anything can be done about a runaway machine with enough
> horsepower at its disposal to kill.

Just to chime in, this is not an X problem per se, but rather the desktop 

X does not have a utility to ask for your password - just a way to blank 
the screen and turn off the monitor.

If you were to prevent X from blanking the screen, then what would likely 
happen is that it will not go blank, but instead you will see either a 
screensaver or a password prompt from whatever screen locker your desktop 
environment is using.

So the issue is really with the desktop environment you are using - there 
should be a control to disable screenlocker.

I am using KDE on my laptop and it does have it.

My CNC machine is controlled from Jetson nano, and I was able to disable 
password prompt, but the screensaver does kick in and I have to muck
around with monitor control key to turn it back on, as the monitor 
touchscreen turns off with the monitor.


Vladimir Dergachev

> I have now been 3 days looking for a way to disable this blanker, trying
> several methods by way of xset, only to find 15 minutes later that its
> been undone and the blanker kicks in regardless.
> So I am proposing that an env variable be named an agreed upon name, and
> that its presence totally disables any and ALL screen blanker's
> regardless of whose desktop of the day is installed.  We can incorporate
> the setting of this, on launching LinuxCNC, and unsetting it when
> LinuxCNC is being shut down.
> If you agree that safety overrides paranoia, please consider this as part
> of the supplied X11 implementations.
> In the meantime, since xset seems powerless to disable it, can someone
> tell me how, in xfce4, to disable it. Haveing it kick in in 10 minutes,
> while the machine is carving a part, and a miss-command does something
> wrong that needs to be stopped as quickly as possible, having a locked
> screen requiring a login via a swarf covering equipt keyboard is simply
> dangerous to both the operator and the machine.  So I'm asking how do I
> get rid of it, totally.  We can operate a monitors power switch if we
> are done for the day, but we can't tolerate anything getting in the way
> of controlling that runaway machine with one keystroke during the day.
> Please advise.  And thank you.
> Cheers, Gene Heskett
> -- 
> "There are four boxes to be used in defense of liberty:
> soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
> - Louis D. Brandeis
> Genes Web page <http://geneslinuxbox.net:6309/gene>
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