On Fri, 23 Oct 2020 16:42:53 +0200
Edward Bartolo via Dng <dng@???> wrote:

> Dear All,
>
> Lately, on an HP Probook 4540s, while booting Devuan Boewulf the
> screen becomes completely unreabled with unsynchronized lines of
> pixels. I will not be surprised if this is some sick joke by HP, to
> force their customers to buy new, but I do not know if this is the
> case with what I am experiencing. The hopelessly corrupted display
> persists even when startx is invoked, but the screen pixels indicate X
> fails to load.
>
> The 'joke' vanishes if I try to reboot the machine without switching
> off power and startx works as if nothing of the sort exists.
>
> I am asking but bearing in mind, the HP is not very Linux friendly and
> that this issue might be some creative joke on their part. Afterall,
> Aitor was right, that HP are not very Linux friendly!
>
> Those who have a solution please reply. I tried the 'nomodeset' kernel
> parameter but it made the issue even worse.

Hi Edward,

The only thing I can add to the discussion is that about a decade ago I
used to see this symptom (a kind of moving "tearing" of the screen to
the point of unreadability) on lots of laptops. I'd need to reboot
several times to get it to work properly and it was a real pain in the
ass. As time went on, I stopped seeing the symptom. I think probably
Linux drivers caught up to my laptop's hardware.

As experiments, I'd try the following to see if they alter the symptom:

* Temporarily try it booting directly to X and see if things get better

* If it uses "plymouth", get rid of plymouth and see if things change

* Try to see if the tearing occurs before or after the running of
udev/eudev/vdev. If after, try changing some video related
udev/eudev/vdev config parameters.

* Boot a System Rescue CD DVD or thumbdrive, and see if the symptom
still occurs. If not, you can slowly exploit the differences between
System Rescue CD and your Devuan installation until you pinpoint the
root cause.

* Boot a live or install disk of the latest unstable Devuan and note
any change in symptom.

* Create a tiny partition on your computer and install a tiny Void
Linux OS, then update with xbps-install -Su so you have an up to date
rolling release system with pretty much the latest kernel and drivers.

* Don't worry too much about the "joke" aspect of the thing. I've seen
this before, on non-HP hardware.

HTH,

SteveT

Steve Litt
Autumn 2020 featured book: Thriving in Tough Times
http://www.troubleshooters.com/thrive