[mythtv-users] Caveats in upgrading from Ubuntu 18.04 + MythTV 29.1 to something newer?

Stephen Worthington stephen_agent at jsw.gen.nz
Tue Apr 25 03:59:34 UTC 2023

On Mon, 24 Apr 2023 21:43:34 -0400, you wrote:

> From Ubuntu 20.04 to 22.04:
>This was much more problematic.
>First, the nvidia drivers weren't loading.  Despite what a google search 
>suggested, "sudo apt install xserver-xorg-video-nvidia-525" is what 
>fixed it.  "sudo apt install nvidia-driver-525 nvidia-dkms-525" led to 
>some weirdness with the proprietary nvidia driver *not* being used by 
>Xorg.  I also had to "sudo apt install flex bison" along the way, as 
>somehow in the OS upgrade, I ended up without the ability to compile the 
>nvidia modules.

I had a problem with the Nvidia drivers not loading recently, also
with the 525 drivers.  What I found in the logs was that X was unable
to find the Nvidia .so files, despite them being in the same location
as usual.  So I had to add this to my /etc/X11/xorg.conf file:

# For some reason X is unable to find the Nvidia drivers, so manual
# are required.
Section "Files"
    ModulePath "/usr/lib/x86_64-linux-gnu/nvidia/xorg/"
    ModulePath "/usr/lib/xorg/modules"

I have not tried removing it again when a new version of the Nvidia
525 drivers was installed.

Your problem with nvidia-dkms-525 may be related to a new thing that
the Nvidia drivers do on Ubuntu, which is to install pre-built *.ko
module files instead of compiling them against each kernel with dkms.
For some reason this does not always work, and you can get a failure
to load the Nvidia drivers.  It is good when it does work, as you do
not have to wait for the dkms compiles when installing new kernels.  I
have one 22.04 machine on 525 drivers where I have removed the
nvidia-dkms-525 package and it works.  On another 22.04 machine I had
bad problems and backed off to 515 with dkms to get it to work again.
I should try updating that machine to 525 again now that there are
updated 525 versions since I had that problem.

For installing Nvidia drivers now, I use the "ubuntu-drivers install"
command, rather than trying to specify the packages in an apt command.

>After the above steps (which took more time to figure out than I'd like 
>to admit), the resulting MythTV box was not ideal in two ways:
>1) The deinterlacing with the 525 drivers was noticeably *worse* than 
>the nvidia 390 drivers that Ubuntu 20.04 was fine with.  I think 
>switching to NVDEC for decoding made it better.  But I'm not convinced 
>that the deinterlacing is better than what VDPAU got me with older 
>driver versions.

I find this interesting, as I am very sensitive to deinterlacing
problems and have not had this happen to me.  I have been using both
VDPAU and NVDEC at times on the 525 drivers and can see no difference
between them, except for the NVDEC drivers supporting more 4K files
than VDPAU, and NVDEC not supporting some older video files.  I do not
remember any difference in the deinterlacing as I moved through the
driver versions from 390 upwards.  I am using Nvidia GT1030 cards.

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