Ways of Using NVIDIA Graphics Card in a Linux Machine

There are different ways of using NVIDIA graphics drivers in Linux machine, such as:
1. Using it as the main GPU
Cons:
a. Significantly more power consumption compared to using Intel HD
b. Known artifacts, which is sometimes portion of the screen gets corrupted. This goes away when mouse is hovered over, but is still annoying

2. Using it with Bumblebee to get PRIME-like feature.
As most of you are probably familiar, in Windows, the default setting is that NVIDIA GPU is turned on only if it's needed. For example when you're running a game, it's turned on, but when you're browsing, editing a text-file, or something else lightweight, it's turned off to conserve the battery. In Linux, however, such feature doesn't work. The open-source community, however, created an effort to get a similar feature: Bumblebee project. With Bumblebee, Intel HD is the one that renders to the screen. NVIDIA GPU, when requested, is used to render things to a transparent layer, which is then transported into the Intel HD buffer to be rendered to the screen. Unliked PRIME feature in Windows, however, the switch between when to use NVIDIA vs. Intel is not automated. You'll have to specifically tell a program to use which GPU.
For more information: https://github.com/Bumblebee-Project/
Cons:
a. Setup can be pretty complex
b. The perf is not as good as using NVIDIA to render directly to the screen, because of the additional step of transporting NVIDIA-rendered buffer to screen buffer, which is a CPU-consuming step

3. Using nvidia-xrun to run a separate entity of X server which uses NVIDIA GPU.
This is actually my favorite, because this is very easy to setup. To give a little bit of background, in Linux, there is a component called Display Manager the job of display manager is to provide an interface for application to render stuffs onto the screen. In other words, it's a bridge between application and display hardware. And for any applications to render significant graphics into the screen, they use the API provided by X server. So the idea here is to run 2 separate X servers. The first is used to run typical lightweight workload such as text-editing, web-browsing, etc, and is backed by Intel HD drivers. The second is backed by NVIDIA drivers, hence is using the NVIDIA card, and is only run when there is a need to run an application that requires it. So this is very similar to Bumblebee project, except is much simpler.



Special thanks to:
https://wiki.archlinux.org/index.php/NVIDIA
https://github.com/Witko/nvidia-xrun
https://github.com/Bumblebee-Project/

Upgrading Ubuntu Linux Kernel

Sometimes there are problems with the kernel that a Ubuntu distro ships with. For example, on 16.04 LTS release image, my ThinkPad Yoga 14 S3 often fails to resume from sleep. And the latest version of this writing, 4.13.12, caused intermittent WiFi issue which required me to re-connect to the AP periodically.

In short, sometimes there are needs to switch to different kernel versions (sometimes older) to find the one that is the most stable for the hardware in subject.

Here's how you upgrade Linux Kernel:
1. Pick the kernel to update to in:
http://kernel.ubuntu.com/~kernel-ppa/mainline/

2. Download the 'generic' version of the right architecture (3 deb files)

3. Install the kernel from terminal
sudo dpkg -i *.deb

4. Reboot your system!

Tips:
You can boot to a different kernel version in Ubuntu. While booting up, once you get into GRUB bootloader, pick "Advanced Option" and select the version of kernel you want to use.

Using Scanner in Ubuntu

After installing Epson scanner drivers from official Epson site, there are a few tools that can be used to scan:
1. scanimage terminal application
2. xsane GUI app
3. Simple Scan GUI app

The GUI apps are straight-forward to use. But I found that sometimes they just don't work. So I use the Terminal method when that happened :)

scanimage --resolution 300 --mode Color --format ppm > output.ppm

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

Changing Device Permission Permanently through udev

Sooo, I've just bought a Raspberry PI for a project, along with a $5 webcam for a Computer Vision experiment. I immediately tried the quality of the camera using "cheese" Linux program on my Ubuntu laptop, and it worked out fine. Unfortunately, in Raspberry PI, the program simply wouldn't detect the camera.

After hours of debugging, apparently the problem was with permission. The webcam enumerates as /dev/video0, which has 0660. Since "cheese" runs as "other", it doesn't have the permission to read it. Manually modifying it through "chmod o+rw /dev/video0" does the job. However, I want a more permanent and elegant solution.

The solution is to use udev. Here're the steps:
1. Get the webcam's vendorId and productId through lsusb/dmesg.
2. Get its DRIVER and SUBSYSTEM (properties required for udev setting) through "udevadm info -a -n [device_path]" (device_path is sth like /dev/video0)
3. Create new rules as instructed here: https://wiki.archlinux.org/index.php/Udev#Video_devices
4. As a reference, in my case the rule file is created here: /etc/udev/rules.d/83-webcam.rules, with the content being: KERNEL=="video[0-9]*", SUBSYSTEM=="video4linux", SUBSYSTEMS=="usb", ATTRS{idVendor}=="05e3", ATTRS{idProduct}=="0510", SYMLINK+="video-cam1", MODE="0666"

What's bold is the part that specifies the permission.


Hope this helps!

Ubuntu 14.04 suddenly won't boot? This is how you debug it!

After a couple days without rebooting my X201 that was running Ubuntu, I decided to reboot the system. And unfortunately, it won't boot afterwards! After passing the Ubuntu's familiar purplish-black blank background, it got stuck in a black screen. What scared me were that pressing caps-lock didn't even turn on the keyboard indicator and I also couldn't enter "console mode" (ctrl + alt + f1). I was scared that the system went into a hard-hang, perhaps because I accidentally installed some craps. However, it turned out that my xserver binary was missing; the file /usr/bin/X didn't exist, for some reason! How did I figure that out? This post explains it.

Ubuntu keeps different the logs of the last boot attempt. These logs can be used to triage booting issue and potentially are useful to fixing it too. It Through these logs, I was able to figure out my xserver issue. This is how you do it:
1. Boot the system, get it to the hanging state. This step is necessary in order to get the log files generated.
2. Boot to a live-session using Ubuntu CD or Ubuntu USB stick
3. Open "[path to partition]/var/log" of the partition where the problematic Ubuntu is installed. Note that this is not just "/var/log" because that belongs to the currently running live session.
4. Sort the log files by modified date, and open the logs that correspond to the booting attempt from step 1.
5. As there are different log files, I'd suggest to first look at boot.log, which is similar to the kernel log that you get from dmesg. If nothing is suspicious there, then it's likely to be a userspace issue.
6. In my case, I found my xserver problem through the log at /var/log/lightdm/lightdm.log. This is the suspicious snippet of the logs:
+0.05s] DEBUG: DisplayServer x-0: Logging to /var/log/lightdm/x-0.log
[+0.05s] DEBUG: DisplayServer x-0: Can't launch X server X -core, not found in path
[+0.05s] DEBUG: DisplayServer x-0: X server stopped

Through a quick google search, I figured that /usr/bin/X is where "X server X -core" is supposed to be located at. In my case, the file was missing, so it was rather obvious. I then rebooted to Ubuntu recovery mode (by holding "shift" right after the system passes bios), and reinstalled xserver via sudo apt-get install --reinstall xserver-xorg.

Hope this post can be useful!

Samsung SSD 850 EVO on ThinkPad X201

I had been contemplating about buying a new laptop to replace my 5 years old ThinkPad X201. My criterion were:
1. It has to run Linux (preferably Ubuntu, as I'm most familiar with this) well, like really well as it'll be my main OS.
2. Small (13" would be the largest)
3. Perhaps with NVIDIA GPU so I can run CUDA stuffs (as I've been into machine learning stuffs these days) on it and so some casual gaming.

Through focusing on criteria (1) and (2), I came across Dell XPS 13 Developer Edition, which is a laptop with native Ubuntu OS. Because it didn't come with Windows, guess what? It actually costed cheaper than the non-developer options that came with Windows! And the best part is that Ubuntu is optimized to run well on the laptop. Tempting. Very tempting. As finding a decent laptop to run Ubuntu had indeed been challenging, I drooled over the one with 256GB SSD and i7 CPU. But still I didn't buy it.

Thankfully, it didn't have an NVIDIA GPU! If only it had it, I'd have already bought it. So what's the deal? Well, I realized that my combo of X201 with Ubuntu had been serving me really well. There had almost been no time I needed more performance than what it offered (except, of course, for casual-gaming purposes, which I rarely do and I already have dedicated gaming devices anyway) So I thought: if it only had Intel's integrated GPU, how would it serve me better than my X201? Not much, really. Moreover, I already had a docking station for my X201! If I were to buy a new laptop, for sure I'd want to get a dock for it, and that'd be like $100+ extra. Bummer..

Long story short, instead of having abandoning it, I decided to give my Thinkpad X201 some love. I treated it with a 500GB Samsung SSD 850 EVO. How did it go? Really sweet! With Ubuntu 14.04 (w/o any form of disk encryption enabled), it booted in 12 seconds! Going to/resuming from hibernate was almost instantaneous! So far I've been loving it so much :)

OSX, Windows, Ubuntu?

I had been a long-time user of OSX for quite sometimes. (+- 4 years) I found its UNIX environment and super-friendly user interfaces to be very useful for especially programming. Macbook's trackpad and keyboard shortcuts have always been my personal favorite as well.
I've always thought that MacBook's so called over-price is actually worth every penny. It has SMS, light sensor, very decent LCD, etc etc.
I still have lots and lots of positive things I'd want to write about MacBook. Software like SizeUp, TextMate, SMC Fan Control, iTerm 2, etc have been easing my life as a programmer so much. Maybe I'll write some articles about how much I loved OSX sometimes.

However, as I am becoming more more into UNIX environment, I've found OSX to not be able to catch up with my needs. First and foremost is because many software applications simply aren't written to work well with OSX! It's inevitable that the main market consumer is still Windows and so many software industry simply writes crappy port of their software for OSX. What I mean by crappy here is lots of memory leaks, not optimized to work efficiently and so on. Sad to say this, but I have to admit that I found my MacBook 5,1 with 8GB of RAM and 2.1 core-2-duo processor to be considerably sluggish compared to a laptop with a similar spec with Windows on it. A very obvious example would be Flash player. Try running a Youtube video on a 5,1 MacBook. Notice how hot your MacBook is? I can't help but to also notice how sluggish it becomes. It's just very annoying sometimes..

On the other hand, since some Linux are open source, the software support is so amazing. For almost every single application that you're searching for, you'd almost always able to find a decent open-source version that substitutes it. It's just amazing to see how much Linux have been growing. Also the driver supports that let things work out-of-the-box is just so sweet... I guess I'll have to write another post dedicated for Linux at some point.

:D
Feel free to start a discussion within this thread. I'm no big fan of one single OS or biased towards any. I have so much positive things to say about Linux, Windows, or OSX. They're just great and bad in their own ways.

Mounting Linux hdd (ext4/ext3/ex2) in OSX

As the title says, here's how to mount Linux partition in OSX:
1. Download MacFuse .dmg from http://code.google.com/p/macfuse/
2. Download fuse-ext2 .dmg from http://sourceforge.net/projects/fuse-ext2/
3. Install them respectively.
4. Reboot your computer?
5. Here is the magic terminal keywords to mount your beloved Linux hdd:

a. First do: 'disktool -l' to find out the name of Linux hdd you're interested in. The name is something like disk0s1 or similar.
b. Next: 'mkdir /Volumes/[HD NAME]' replace HD NAME with your choice of your name. (eg. Linux)
c. After that, 'sudo fuse-ext2 /dev/[LINUX HD NAME] /Volumes/[HD NAME]/ -o force' replace the LINUX HD NAME with the name from part a. above and HD NAME from part b. above

Voila! You're beloved Linux partition is now mounted! :)
Tips: You can add a script to your .profile to automate the steps above every time your computer boots up!

Installing Ubuntu 11.10 on MacBook 5,1 + Tweaks to run it smoother

Previously I had Ubuntu 11.x installed in my MacBook 5,1. However, after I upgraded it to 11.4 (Natty Narwhal) a problem occurred. My Ubuntu didn't boot-up anymore. I googled around and it seemed that 11.4 has problem with video driver that my MacBook uses.
Long story short, I re-installed my whole Ubuntu partition.
Here are some steps of how to do it.

1. If you're triple booting, make sure to have Refit installed. (This is some sort of BIOS emulation for Mac fancy new technology?) But if you're just dual booting, bootcamp is sufficient.
2. If you're planning to install Windows as well, I would recommend to install the windows first before installing the Ubuntu (a lot of people suggest this). Install the Windows using bootcamp as usual.
3. Now to install Ubuntu, burn the image to a cd/dvd, put it inside the disc reader, then reboot your mac. After you hear the boot-indicator beeping sound (before the apple logo), immediately press and hold 'c' (c stands for cd I guess?) This will let your MacBook boots from the Ubuntu image.
4. Make sure NOT to partition your hard-disk from Ubuntu installer! My friend OSX partition was gone because of this. Just to be safe, always partition using DiskUtility.
5. When prompted for swap file during the Ubuntu installation, just ignore it. We don't need it.

6. Now just follow all the installation step prompted and you'll be good to go! :)


Here are several tricks to make Ubuntu 11.10 run smoother. These tricks originally came from different resources I found in Google. I want to share these as they are really helpful. (Thanks to all the original sources)

Wireless card problem:
In some MacBook version, the wifi doesn't work out of the box. To fix this, go to 'additional driver' under the application menu. Look for broadcom adapter then install.

Sluggish graphics:
Again, in some MacBook version, the NVDIA graphic card isn't appropriately configured out of the box. So go to 'additional driver' then try to install one of the listed NVDIA drivers. Some might not allow hibernate, some might not fix the sluggish-ness of your graphics, some might not do both, but some might fix everything! Try one that works for you. If nothing works, try going to NVDIA official site and download their latest driver.


Keyboard shortcut brightness doesn't work:
This one is pretty irritating, but I found the solution to be quite simple.
Edit the text file /etc/X11/xorg.conf (need root access)
In the "Device" section, add up this line:

Option "RegistryDwords" "EnableBrightnessControl=1"

Now save the file, reboot your Ubuntu, and you're keyboard is good to go!

Trackpad "gets in the way" when typing:
Sometimes when you're typing, you accidentally touch the trackpad so the field where you're typing loses the focus. This is due to your hand accidentally touching the trackpad that's really sensitive. (From this I realized how great Apple drivers are!) 
To fix this, install "Pointing devices" from Ubuntu Software Center. Run this program like running ordinary application. There is a really cool tweak to your trackpad, "Detect Palm". Basically this detects the "accidental" touch that happens when you're typing. For me, after installing this, the trackpad doesn't really "get in the way" anymore. (sometimes they still do, but not that often)

Disabling trackpad via terminal
Okay if you don't want to go into all the hassle of downloading additional software just to enable/disable trackpad or any other input device, here is how you do it using terminal.
'xinput list' -> this gives the list of input devices available.
'xinput set-prop [id] "Device Enabled" [1/0] -> to disable/enable the input device.
Just in case you have your trackpad disabled and forget to bring mouse, hit ctrl+alt+t to open terminal and type in the magic keywords above to enable your trackpad. Or maybe aliasing is better!

Okay so those are the tips so far. I'll be updating this if I found new fancy tricks. So far I'm loving my new Ubuntu 11.10!

Have fun with your Ubuntu!