Yesterday I've switched to the gentoo-sources kernel package on Gentoo Linux. And with that, I also attempted (succesfully) to use the propriatary nvidia drivers so that I can enjoy both a smoother 3D experience while playing minecraft, as well as use the CUDA support so I don't need to use cloud-based services for small exercises.
The move to nvidia was quite simple, as the nvidia-drivers wiki article on the Gentoo wiki was quite easy to follow.
Signing the modules
One difference I found with the article (which I've promply changed) is that the signing command, necessary to sign the Linux kernel modules so that they can be loaded (as unsigned or wrongly signed modules are not allowed on the system), was different.
It used to be as follows (example for a single module, it had to be repeated for each affected kernel module):
~# perl /usr/src/linux/scripts/sign-file sha512 \ /usr/src/linux/signing_key.priv \ /usr/src/linux/signing_key.x509 \ /lib/modules/4.12.5-gentoo/video/nvidia-uvm.ko
However, from version 4.3.3 onward (as also explained by this excellent
Signed kernel module support article on the Gentoo wiki) this command
no longer uses a Perl script, but is an ELF binary. Also, the location
of the default signing key is moved into a
Enabling nvidia device files
When the nvidia modules are loaded, additional device files are enabled.
One is the
nvidia0 character device file, while the other is the
nvidiactl character device file. And although I can imagine that the
nvidiactl one is a control-related device file, I don't exactly know
However, attempts to use 3D applications showed (through SELinux denials) that access to these device files is needed. Without that, applications just crashed, like so:
org.lwjgl.LWJGLException: X Error - disp: 0x7fd164907b00 serial: 150 error: BadValue (integer parameter out of range for operation) request_code: 153 minor_code: 24 at org.lwjgl.opengl.LinuxDisplay.globalErrorHandler(LinuxDisplay.java:320) at org.lwjgl.opengl.LinuxContextImplementation.nCreate(Native Method) at org.lwjgl.opengl.LinuxContextImplementation.create(LinuxContextImplementation.java:51) at org.lwjgl.opengl.ContextGL.<init>(ContextGL.java:132) at org.lwjgl.opengl.Display.create(Display.java:850) at org.lwjgl.opengl.Display.create(Display.java:757) at org.lwjgl.opengl.Display.create(Display.java:739) at bib.at(SourceFile:635) at bib.aq(SourceFile:458) at bib.a(SourceFile:404) at net.minecraft.client.main.Main.main(SourceFile:123)
Not really useful to debug for me, but the SELinux denials were a bit more obvious,
showing requests for read and write to the
nvidiactl character device.
matchpathcon I found out that the device files had to have the
xserver_misc_device_t type (which they didn't have to begin with, as the device
files were added after the automated
restorecon was done on the
So, adding the following command to my local init script fixed the context setting at boot up:
restorecon /dev/nvidiactl /dev/nvidia0
Also, the domains that needed to use nVidia had to receive the following addition SELinux-policy-wise:
Perhaps this can be made more fine-grained (as there are several other device
files marked as
xserver_misc_device_t) but for now this should suffice.
Optimus usage with X server
The other challenge I had was that my workstation uses an integrated Intel device, and offloads calculations and rendering to nVidia. The detection by X server did not work automatically though, and it took some fiddling to get it to work.
In the end, I had to add in an
nvidia.conf file inside
with the following content:
Section "ServerLayout" Identifier "layout" Screen 0 "nvidia" Inactive "intel" EndSection Section "Device" Identifier "nvidia" Driver "nvidia" BusID "PCI:1:0:0" EndSection Section "Screen" Identifier "nvidia" Device "nvidia" Option "AllowEmptyInitialConfiguration" EndSection Section "Device" Identifier "intel" Driver "modesetting" EndSection Section "Screen" Identifier "intel" Device "intel" EndSection
And with a single
xrandr command I re-enabled split screen support (as by
default it now showed the same output on both screens):
~$ xrandr --output eDP-1-1 --left-of HDMI-1-2
I also had to set the output source to the nVidia device, by adding the following
lines to my
xrandr --setprovideroutputsource modesetting NVIDIA-0 xrandr --auto
And with that, another thing was crossed off from my TODO list. Which has become quite large after my holidays (went to Kos, Greece) as I had many books and articles on my ebook reader with me, which inspired a lot.