Kernel 5.4.0-9 breaks PRIME Synchronization

Desktop
1

In what could be a disappointing turn for nvidia optimus users it seems the latest kernel update breaks use of PRIME Synchronization.
Whether a kernel, nvidia, xserver or Ubuntu issue not sure, wondering if any others see or know?

Ex. ( 1st. PRIME Synchronization value is what matters.

$ uname -a && xrandr --verbose |grep PRIME && sudo cat /sys/module/nvidia_drm/parameters/modeset
Linux doug-Lenovo-IdeaPad-Y510P 5.3.0-24-generic #26-Ubuntu SMP Thu Nov 14 01:33:18 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
PRIME Synchronization: 1
PRIME Synchronization: 1
PRIME Synchronization: 1
[sudo] password for doug:
Y

$ uname -a && xrandr --verbose |grep PRIME && sudo cat /sys/module/nvidia_drm/parameters/modeset
Linux doug-Lenovo-IdeaPad-Y510P 5.4.0-9-generic #12-Ubuntu SMP Mon Dec 16 22:34:19 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
PRIME Synchronization: 0
PRIME Synchronization: 1
PRIME Synchronization: 1
[sudo] password for doug:
Y

2

If it previously worked and now doesn’t, this sounds like something which should be reported as a bug.

ubuntu-bug linux and follow the prompts.

1 Like
3

Most likely this isn’t a kernel bug and Nvidia would just need to release an update to support newer kernels. Maybe try https://launchpad.net/ubuntu/+source/nvidia-graphics-drivers-440

4

Yeah, filed bug against nvidia-driver-440 in launchpad yesterday.

Also remembered this happened about 2 years ago, was fixed with a debian/dkms_nvidia patch, I.e, buildfix_kernel_4.15.patch

5

Thanks. Discussion moved to Launchpad.