Dual GPU Laptop in Ubuntu. (NVIDIA and Intel HD5200)

I just bought myself a Thinkpad Yoga 14. I'm loving its IPS FHD screen which is accompanied with NVIDIA 840m GPU in addition to its onboard Intel HD5200, which more than enough to satisfy my occasional craving to game and do 3D rendering :)

Here are some useful stuffs I learned about dual GPU setup in Ubuntu.

1. NVIDIA isn't installed by default.
• It's running on Intel HD5200 by default because that's what's installed with the default Ubuntu setup.
• Instruction to install NVIDIA driver can be found here:
• Find out the latest driver that is compatible with your GPU.
• http://www.nvidia.com/Download/index.aspx
• To ease  out the process, install the driver via apt-get (e.g. sudo apt-get install nvidia-375 if NVIDIA page says that your latest driver is 375.66)
2. After your driver is installed according to step (1), you can switch between NVIDIA or onboard GPU via 'nvidia' program (open app search pane, type 'nvidia')

• Unfortunately, the new GPU to be used is only applied after a logout..
3. How to switch GPU without logging out or restarting?
1. Fire up terminal
2. sudo prime-switch nvidia  to switch to nvidia
3. sudo prime-switch intel  to switch to nvidia

Enjoy! I'll update this page as I find new tips and tricsk.

Source:

https://linuxconfig.org/how-to-install-the-latest-nvidia-drivers-on-ubuntu-16-04-xenial-xerus

Downgrading Mysql 5.7 to Mysql 5.6

I just got a new system where I installed mysql through apt-get. It installed 
mysql version 5.7, which unfortunately didn't serve my purpose well. That 
version added a new constraint such that when there's a GROUP BY keyword in a
SELECT clause, the only columns that can be selected are those that are part of
GROUP BY. 

I could possibly disable the constraint, but I just felt like sticking with
version 5.6 which had been working fine for me. Because of this, I decided to
downgrade to 5.6.

Step 1. Remove all 5.7 components. The second line is important, because
it seems that there are some settings that if not deleted, version 5.6 wouldn't
run.

sudo apt-get purge mysql-server mysql-client mysql-common mysql-server-core-5.7 mysql-client-core-5.7
sudo rm -rf /etc/mysql /var/lib/mysql
sudo apt-get autoremove
sudo apt-get autoclean

Step 2. Install version 5.6

 sudo add-apt-repository 'deb http://archive.ubuntu.com/ubuntu trusty universe'
 sudo apt-get update
 sudo apt install mysql-server-5.6 * see note below if you get an error
 sudo apt install mysql-client-5.6

Step 3. Restart the service

sudo service mysql stop
sudo service mysql start

XKB Keyboard Mapping - Remapping a Key

I just bought myself a S3 Yoga 14. After installing Ubuntu 16.04, I found out that the key that was suppose to spew out 'pipe' and 'backward slash' (when shifted) actually spewed 'greater than' and 'less than'. This little write up explained how I fixed it.


As a reference, please read this first to get some relevant information:
http://www.antoniusdharijanto.com/2015/10/simple-key-re-mapping-on-ubuntu-1404.html


Steps
1. Figure out the keycode of the offending key
There's a little program 'xev' that when runs from terminal, it would give information about whatever key is pressed, including the keycode.

2. Figure out what the key from (1) is supposed to map into.
Since I have another laptop running Ubuntu, I just run xev there and figure out the keycode of the key 'pipe' and get the action from /usr/share/X11/xkb/keycodes/evdev

2. Re-map that keycode to pip
Open up /usr/share/X11/xkb/keycodes/evdev and remap that keycode to the proper functionality.


Update:
The key to be updated was:
<BKSL> = 94; // Note that other occurence of BKSL has to be commented out for this to work