On 7/19/20 9:22 PM, Bruce wrote:
> I have an older HP G70-460US laptop.  I recently did a fresh install of
> Ubuntu 20.04.
> 
> This laptop streams to my Samsung TV.  I use an HDMI connection. The
> older version that was installed did this very well.  The new version
> shows the Ubuntu logo during boot and then (I think) as the desktop is
> loaded, the screen blanks on both the TV and the laptop.  The mouse
> cursor shows on the laptop and the laptop screen seems to be flashing. 
> The TV responds as though there is no signal to it.
> 
> My Google searches turn up lots of problems with Nvidia.  This laptop
> has onboard Intel drivers.
> 
> Can anybody point me in the proper direction?
> 
> I will post any additional info necessary.
> 
> 
> Bruce
> 

This sounds like the old intel i915 KMS modesetting bug, or power saving
glitch.  The TV shows the boot but when modeseting kicks in it all goes
blank - the GPU freezes to conplete system lock, depending on kernel and
effects some recent kernels in the 4.x and 5.x versions. It may also be
that your kernel is not built with some required framebuffer features,

The first thing I would check is the X.org log.  It may contain clues as
too what is happening.  Log for current boot is usually
/var/log/Xorg.0.log with previous log in Xorg.1.org

if your human readable text logs are missing refer to your systemd
documentation.

Also check your BIOS.  There may be a GPU/PCI setting that was ok with
older kernels and X.org but is no longer appropriate.

If modesetting is the issue, you can try modifying your grub boot line
to add i915 specific parameters or to disable it. Note that UMS (user
mode setting) via X.org may not work on your newer kernel. Thus you may
be SOL.

https://wiki.debian.org/KernelModesetting
https://ubuntuforums.org/showthread.php?t=1613132
https://bbs.archlinux.org/viewtopic.php?id=235352
https://wiki.archlinux.org/index.php/Kernel_mode_setting



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