UBUNTU-MATE 22.04 (and 24.04) on NUC 7i5BNB has short black screen intervals with some kernels

[eldendo]

I first remarked this behavior on 22.04 with kernel 6.5.0-40. It was resolved with 6.5.0-45 But back with 6.8.0-45,47,48 and later

I did a fresh install with 24.04 but this changed nothing.

So I am stuck with 22.04 and 6.5.0-45

thx

[Bombilla]

Hi, @eldendo and welcome to the Ubuntu MATE Community!

[tkn]

Hi, @eldendo and welcome

I had the same issue and found a solution: disable GPU passthrough (GPU passthrough was introduced into the kernel at the exact time the irregular "on/off-flashing" began.)

if you are up to editing the config of the bootloader this might help:
open a terminal and type:

sudo pluma /etc/default/grub

replace this line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

with this

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash intel_iommu=igfx_off"

save, close and run grub updater

sudo update-grub

and reboot

More things to try in this thread (read whole thread first):

Random flickering on displayoutput?

Best solution Since I also upgraded my old Acer Swift One to 24.04 but the "better solution" did not work, I had to fall back on the first mentioned solution. It works perfectly but I deemed it unacceptable for a laptop because of battery life. So I kept on searching for a solution that, besides solving the problem, also behaves a bit more battery friendly and I found what I was looking for: Use this instead of the line mentioned in the previous post: GRUB_CMDLINE_LINUX_DEFAULT="quiet splash…

[eldendo]

This seems to work ! Thx !

[eldendo]

Sadly, the flashing is back after some time (more than half an hour after boot)... I will investigate the other solutions this weekend...

[eldendo]

OK, it works now. I had to execute grub-install after update grub

[eldendo]

After all, It doesn't work yet...
This morning after booting it was even worse... the screen flashed constantly. Booting with kernel 6.5.0-45 worked at usual and then rebooting with the latest used 6.8.0 (without power off) worked again OK. (all on 22.04).
all this with intel_iommu=igfx_off
So it looks like the old kernel sets some switch on the hardware which is not reset by rebooting but is reset by power off...

[ricmarques]

Hi, @eldendo

Could you please try, when you are in one of your boots that has the screen flickering / flashing problem, to write the following command and report the output in another reply in this topic?

cat /proc/cmdline

The idea of that command is to double check that the intel_iommu=igfx_off that @tkn has suggested is really always getting added as one of the kernel parameters at boot time.

[eldendo]

Hi, ricmarques
here the it the result of cat /proc/cmdline:

BOOT_IMAGE=/boot/vmlinuz-6.8.0-49-generic root=UUID=b549c887-cb5a-4389-8f5f-e03ab506d126 ro quiet splash intel_iommu=igfx_off vt.handoff=7

but today no problems after startup...
I'll continue to investigate