Run a Program on your dedicated Nvidia graphics card on Linux

I've got a new laptop, and in it I have an Nvidia graphics card. The initial operating system installation went ok (Ubuntu 20.10 Groovy Gorilla is my Linux distribution of choice here), but after I'd done a bunch of configuration and initial setup tasks it inevitably came around to the point in time that I wanted to run an application on my dedicated Nvidia graphics card.

Doing so is actually really quite easy - it's figuring out the how that was the hard bit! To that end, this is a quick post to document how to do this so I don't forget next time.

Before you continue, I'll assume here that you're using the Nvidia propriety drivers. If not, consult your distribution's documentation on how to install and enable this.

With Nvidia cards, it depends greatly on what you want to run as to how you go about doing this. For CUDA applications, you need to install the nvidia-cuda-toolkit package:

sudo apt install nvidia-cuda-toolkit

...and then there will be an application-specific menu you'll need to navigate to tell it which device to use.

For traditional graphical programs, the process is different.

In the NVIDIA X Server Settings, go to PRIME Profiles, and then ensure NVIDIA On-Demand mode is selected. If not, select it and then reboot.

Then, to launch a program on your Nvidia dedicated graphics card, do this:

__NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia command_name arguments

In short, the __NV_PRIME_RENDER_OFFLOAD environment variable must be set to 1 , and the __GLX_VENDOR_LIBRARY_NAME environment variable must be set to nvidia. If you forget the latter here or try using DRI_PRIME=1 instead of both of these (as I advise in my previous post about AMD dedicated graphics cards), you'll get an error like this:

libGL error: failed to create dri screen
libGL error: failed to load driver: nouveau

The solution is to set the above environment variables instead of DRI_PRIME=1. Thanks to this Ask Ubuntu post for the answer!

Given that I know I'll be wanting to use this regularly, I've created a script in my bin folder for it. It looks like this:

#!/usr/bin/env bash
export __NV_PRIME_RENDER_OFFLOAD=1;
export __GLX_VENDOR_LIBRARY_NAME=nvidia;

$@;

Save the above to somewhere in your PATH (e.g. your bin folder, if you have one). Don't forget to run chmod +x path/to/file to mark it executable.

Found this useful? Does this work on other systems and setups too? Comment below!

Rendering LaTeX documents to PDF on Linux (and maybe Windows too)

I'm starting to write another report for University, and unlike other reports, this one apparently has to be a rather specific format. To that end, I've got two choices, apparently: Use the provided Word / LibreOffice template, or use a LaTeX template instead. After the trouble and frustration I had with LibreOffice for my previous report, I've naturally decided that using the LaTeX template might be a good idea.

After downloading it, I ended up doing some research and troubleshooting to get it to render properly to a PDF. Now that I've figured it out, I thought I'd share it here for anyone else who ends up experiencing difficulties or is unsure on how it's done.

The way I'm going to be using it is with a tool called Pandoc. First, install it like so:

sudo apt install pandoc texlive-fonts-recommended

Adjust as necessary for your distribution - Windows users will need to read the download instructions. The texlive-font-recommended package is ~66MiB(!), but it contains a bunch of fonts that are needed when you're rendering LaTeX documents, apparently.

With the dependencies installed, here's the command to convert a LaTeX document to a PDF:

pandoc -s input.tex -o output.pdf

Replace index.tex with the path to your input file, and output.pdf with the desired path to the output file. I haven't figured out how to set the font to sans-serif yet, but I'll probably make another post about it when I do.

Found this helpful? Still having issues? Let me know below! I don't have analytics on here, so that's the only way I'll know if anyone reads this :-)

Sources and Further Reading

• The LaTeX Project
• Pandoc
• Pandoc LaTeX -> PDF font issue

Run a program on your dedicated AMD graphics card on Linux

I've recently figured out how to run a program on my dedicated AMD R7 M445 graphics card in Ubuntu 17.04, and since it's taken me far too long to around figuring it out, I thought I'd note it down here for future reference - if it helps you too, let me know in the comments below!

Update October 2020: If you have an Nvidia graphics card, then you probably want to read my newer post here.

It's actually really simple. First, check that your dedicated AMD graphics card shows up with lspci:

lspci

If it's anything like my setup, you'll get a pair of rows like this (though they might not be next to each other):

00:02.0 VGA compatible controller: Intel Corporation HD Graphics 620 (rev 02)
01:00.0 Display controller: Advanced Micro Devices, Inc. [AMD/ATI] Topaz XT [Radeon R7 M260/M265 / M340/M360 / M440/M445] (rev c3)

Thankfully, my dedicated AMD card is showing (better than it did in previous versions of ubuntu, too, which thought it was an M225!). Next, we need to check that the amdgpu kernel module is loaded with a quick lsmod:

lsmod | grep -i amd

On my laptop, I get this:

amdkfd                139264  1
amd_iommu_v2           20480  1 amdkfd
amdgpu               1564672  1
i2c_algo_bit           16384  2 amdgpu,i915
ttm                    98304  1 amdgpu
drm_kms_helper        151552  2 amdgpu,i915
drm                   352256  9 amdgpu,i915,ttm,drm_kms_helper

Yay! It's loaded. Now to do a test to see if we can run anything on it:

glxinfo | grep "OpenGL renderer"
DRI_PRIME=1 glxinfo | grep "OpenGL renderer"

The above runs glxinfo twice: Once on the integrated graphics card, and once on the dedicated graphics card. The key here is the DRI_PRIME=1 environment variable - this tells the amdgpu driver that this process should run on the dedicated graphics and not the integrated graphics card. On my machine, I get this output:

OpenGL renderer string: Mesa DRI Intel(R) HD Graphics 620 (Kabylake GT2) 
OpenGL renderer string: Gallium 0.4 on AMD ICELAND (DRM 3.9.0 / 4.10.0-33-generic, LLVM 4.0.0)

As you can see, the latter invocation of the command ran on the dedicated AMD graphics card, and the former on the integrated graphics. So simple!

Now that we've verified that it works, we can do it with any program:

DRI_PRIME=1 inkscape

Did this you find this helpful? Did it work (or not)? Let me know in the comments!

Sources

• PRIME on the Arch Linux Wiki

UFW and Samba

Today I have another post for you about Samba. Today I found that people couldn't actually access the samba shares I set up (I must have forgotten to test them). They were getting a weird "The Network Path was not found" error. Strange. After looking into it, I found that I didn't unblock the right ports in ufw. You see, Samba operates using two listeners, one called smbd, and the another called nmbd. I had forgotten to read the output of netstat -peanut correctly, and I missed a few ports.

For future reference (and for others having the same problem), here's the list of commands you need to enter in order to use shared folders with Samba correctly:

sudo ufw allow 139/tcp
sudo ufw allow 445/tcp
sudo ufw allow 137/udp
sudo ufw allow 138/udp

Hopefully it doesn't take you as long to fix your problem as it did mine...!

Custom Brightness Controller for Ubuntu

While I love Ubuntu's desktop, the brightness and volume controls are rather annoying as they don't provide a great degree of control. To fix this, I wrote a bash script to control the brightness. Here's what I came up with:

#!/usr/bin/env bash
increment=10
backlight_prefix=/sys/class/backlight/intel_backlight/

echo $1
if [[ "$1" = "decrease" ]]; then
    echo decreasing
    increment=$(expr -${increment})
fi

cur_brightness=$(cat ${backlight_prefix}brightness)
max_brightness=$(cat ${backlight_prefix}max_brightness)

new_brightness=$(expr ${cur_brightness} + ${increment})

# Permissions changes on brightness: 
## change group to sbrl
## add g+w
# Old command:
#gksudo -- bash -c "echo ${new_brightness} >${backlight_prefix}brightness"
echo ${new_brightness} >${backlight_prefix}brightness

####################
### Notification ###
####################
### uncomment the following line to disable the notification
#exit
# Calculate the percentage
new_percent=$(echo "(${new_brightness} / ${max_brightness}) * 100" | bc -l)
new_percent=$(printf "%.1f" "${new_percent}")

echo new_percent: $new_percent

max_bar_length=100
bar_length=$(echo "(${new_percent} / 100) * ${max_bar_length}" | bc -l)
bar_length=$(printf "%.0f" "${bar_length}")

n_bar=$(head -c $bar_length < /dev/zero | tr '\0' '=')

# Kill the previous notification
killall notify-osd
notify-send "Brightness: ${new_percent}%" "${n_bar} (${new_brightness})"
#notify-send "Brightness" "${new_percent}%"

(Pastebin, Raw)

To use the above, you need to do several things. Firstly, you need to find your screen's brightness settings. Open a terminal, and navigate to /sys/class/backlight, and find your backlight's folder. Mine is intel_backlight, but yours might acpi_video0. Once found, you should have a file called brightness inside it. Change the value of the backlight_prefix variable on line #3 to equal the path to this folder, not forgetting the trailing slash.

You then need to alter the permissions on the brightness file in order to allow your user account to change it - otherwise you will get prompted for your password every time you change your brightness! To do this, open a terminal and navigate to the folder we found earlier that contains the brightness file. Change the user group to be your username with sudo chgrp username brightness, and then allow write access to group members with sudo chmod g+w brightness. If this doesn't persist across reboots, you might need to add these commands to your rc.local or Xsession files.

It should work now. If you don't want the notification to show every time you change your brightness (or if it doesn't actually work), uncomment line #27.

Adding a New Samba User

I found myself looking up how to create a new user in samba for about the 5th time today, so I tought I'd post about hwo to do it here so I don't forget :P

Starting from version 4, from what I can tell, Samba doesn't use the local unix accounts on your system. You need to create Samba accounts instead.

To do this, run the following command:

sudo smbpasswd -a username

Then type and retype the password you want for the new account. Note that you need to have a local unix account created under the same name as the samba account that you want to create. If you don't want a real account under the name of the samba account that you want to create, you can create a 'dud' account without a home directory or shell like so:

sudo useradd username --shell /bin/false

I hope this helps someone besides myself. If it did, try commenting below. You don't need an account, and you don't have to provide your email address either (though I seriously won't spam you at all if you do provide it!).

Ubuntu: Second Impressions

I've had my laptop dual booted with Ubuntu for a while now, and I've been using Ubuntu in a Virtual Machine and as a live CD, but I've only just gotten around to rearrenging my partitions and reimaging my Ubuntu partition with Ubuntu 15.04. Previously, I had a bunch of issues with ubuntu (for example my laptop kept heating up), but I seem to have solved most of them and I thought that I'd post here about the problems I encountered, how I fixed them, and what I think of the latest version of ubuntu.

Firstly, I installed ubuntu from a live CD iso on my flash drive. Annoyingly, I used the 32 bit version by accident, and had to do it again. It would be nice if it told you which version you were about to install. Anyway, I found the installer to be rather temperamental. It kept freezing for ages, and all I could do was wait.

After the installation finished, I was left with a brand new, and very buggy, 64 bit Ubuntu 15.04 installation. As soon as it booted, the first job was to stop my cursor from flickering. Because I have an Nvidia GeForce 550M GPU, Ubuntu didn't recognise it properly (it detected it as a second 'unknown display') and so custom drivers were needed to fix it. I found this post, which guided me through the installation of both bumblebee (to control which of my two GPUs I use), and the official Nvidia drivers for my graphics card.

After banishing the flickering cursor, I found my laptop cooler, though it still wasn't right. Next up was to install thermald, indicator-cpufreq and lm-sensors. This trio of packages automatically controls the frequency of your CPU to both save power and prevent overheating. Normally, linux doesn't pay any attention to the frequency of the CPU of it's host system, leaving to run at it's maximum speed all the time - which causes battery drain and overheating.

Now that my laptop wasn't overheating too much, I could focus on other problems. When in Windows 7, I have something called SRS Premium Sound. It is brilliant at tweaking audio just before it reaches the speakers to improve it's quality. I quickly found when I got this laptop that it was essential - the speakers are facing downwards and the output sounds 'tinny' or 'hollow' without it. Since linux doesn't have SRS, the next best thing was PulseAudio, which provides you with an equaliser to tune your sound output with. Note that PulseAudio does actually work with Ubuntu 14, even though some people have said that it has been discontinued (I don't think it has?).

The other thing that needed changing was my touchpad. I felt like I had to hammer it in order to get it to recognise my touch, whereas in Windows it picked up the lightest of touches. My solution was to add the following to my .profile:

synclient FingerLow=2
synclient FingerHigh=3
synclient AccelFactor=0.145
synclient TouchpadOff=0
synclient MinSpeed=1.25
synclient MaxSpeed=2
synclient CoastingFriction=30

This improved the responsiveness of my touchpad a whole lot to the point where I could actually use it without getting frustrated :)

That covers the main problems I came across. As for what I think, I'm finding Ubuntu to be a great operating system to work with - now that I've worked most of the bugs out. Things like indicator-cpufreq and thermald ought to be automatically installed on systems that support them at install time. You should also be prompted to install bumblebee and the offical nvidia graphics drivers at install time too, as a system with multiple GPUs (i.e. integrated graphics and a graphics card) are pretty unusable without them. Sensible default settings would be nice too - nobody likes hammering their touchpad just to get a response.

The Ubuntu unity desktop developers seem to have remvoved a bunch of configuration options from the GUI in recent releases. Hopefully they wil readd them - it's rather annoying to have to enter the terminal to change something as simple as the login screen background.

On the plus side, Ubuntu seems to load much faster than Windows 7, and is more responsive too. I also feel like I have more screen space to work with as there isn't a task bar taking up space at the bottom of the screen. The customisability is amazing too. I am finding that there are far more things that you can tweak and fiddle with in Ubuntu compared to Windows.

To finish off this post, here's a list of smaller problems I had, and a link to the appropriate post that fixed it for me:

• Change folder icons in nautilus
• Change the login screen background
• Change the default system sounds
• Basic steps to take to secure your Ubuntu installation
• Mount a partition on boot
• Change Bluetooth device name