Ubuntu 14.04 : How to install 4.4.8 Kernel

Hello,

Here are some simple steps to install Kernel 4.4.8 on your Ubuntu machine.

Open terminal and execute following commands in given order.

32bit Ubutnu:

Lets download the packages needed for installation.

Now, install downloaded packages: it will take a while, just sit back and relax

64bit Ubuntu:

Same way as earlier, lets download required packages first,
Installing downloaded packages: same as that of 32bit

We are done! Just reboot system and you should see newer Kernel installed on your system.
Cheers!!

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issue "/usr/include/linux/errno.h:1:23: fatal error: asm/errno.h: No such file or directory" while cross-compiling

Aloha,

So, making this post as it did cost me more than couple of hours to figure-out what the hell is happening.

I was building some (secrete) driver for android yesterday and I needed to install cross-compile tool-chain  for same, but while installing tool-chain on Ubuntu some of the packages already installed got removed by package installer.

Next, I set up the environment for building driver and kicked the build. Suddenly I started getting following error from compiler:


I did not noticed that some package has been forcefully removed while installing tool-chain. After some Googl'ing I found the package that needs to be installed.

Just install following package and issue will disappear :)

$sudo apt-get install linux-libc-dev:i386

cheers!!

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Tmuxing with Tmuxinator

Ooolo,

So, Here is what’s happened, I was doing some testing with driver for #top_secrete project. So each time to test my driver, I have to go through following steps,

- ssh to target platform (tab0), run vim to edit code
- ssh to target platform (tab1), cd to source dir
- source environment
- build/install
- ssh to target (tab2), cd to log dir and start ldmesg script to continuously monitor dmesg logs
- ssh to target (tab3), cd to test dir and start test (server)
- ssh to target (tab3), cd to test dir and start test (client).


aahh, lots of steps and if driver crashes during testing (and that's what happens most of the times), I have to repeat this whole process again. Above described (steps) stuff is mostly unproductive. So how to avoid it??

So here comes tmux,

Tmux (terminal multiplexer) allows you to switch between multiple programs in single terminal. Its similar to screen.

Getting started resources for tmux :
-Part1
-Part2

So if I login in to target system over SSH in one terminal and start tmux, I can create multiple tabs inside single terminal using tmux to run multiple programs. This solves partial problem i.e. multiple SSH logins, but sill I have to do lots of stuff manually after creating multiple tabs using tmux. I needed further automation in the process...

After doing some googling I came across tool called tmuxinator.
It does exactly what's needed. Tmuxinator is awesome tool that allows you to configure tmux session i.e. how many TTYs (tabs) to start with, executing some commands on start, splitting window, base/root directory for each tabs can be configured separately, cool right!

Getting started resources for tmuxinator:
-Basics

So tmuxinator automates most of the steps above, it launches tmux, creates multiple tabs, source env, changes dir to specific directory and additionally we can maintain multiple project settings/profiles much easily and what it needs is simple configuration file.

Cheers!
(will update more soon!)

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How to increase vmalloc size [vmalloc: allocation failure]

Hello,

So this is what happened, I was working on the graphics driver and testing some GLBenchmark applications to see if everything is smooth and healthy. But one of the test was always failing for unknown reason (at that time). I have put more than couple of hours to debug that. I was ignoring some errors in dmesg (kernel log) that I was getting,

May 18 14:53:38 pc-vbox kernel: [412318.373157] vmap allocation for size 37752832 failed: use vmalloc=<size> to increase size.
May 18 14:53:38 pc-vbox kernel: [412318.373161] vmalloc: allocation failure: 37748736 bytes
May 18 14:53:38 pc-vbox kernel: [412318.373163] GLBenchmark27_X: page allocation failure: order:0, mode:0xd2


Latter I found that application was quite a heavy and vmalloc is failing due to insufficient space. On x86_32 systems default vmalloc size is 128MB and can be override by vmalloc kernel boot option. vmalloc() allocates block of memory with continuous virtual addresses or pages  (no guarantee that pages are actually contiguous in physical RAM) . You can find current vmalloc size of your system as bellow,

$cat /proc/meminfo | grep -i vmalloc

VmallocTotal: 122880 kB
VmallocUsed: 28216 kB
VmallocChunk: 94156 kB


How to increase vmalloc space?
We have to modify the kernel boot options in grub in order to do that.
open /etc/default/grub and make following change,
This will increase total vmalloc space to 512MB, next you need to update the grub as follows,

$sudo update-grub

After this corresponding  change will be reflected in /boot/grub/grub.cfg file as bellow,


Then just reboot the system and that solved my problem. Its not the thumb rule to set vmalloc to 512M but just set to what solves your problem!

After reboot you can see vmalloc size increased,

$cat /proc/meminfo | grep -i vmalloc
VmallocTotal:     524288 kB
VmallocUsed:       64768 kB
VmallocChunk:     366544 kB

cheers

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Capture and monitor dmesg continuously

Greetings folks!

If you are working on device drivers for Linux/Android we do rely on dmesg for almost all of the times. But you know the dmesg buffer is limited, its circular buffer. So what ever overflows the buffer is lost for good (?). We feel need to increase the buffer size but its not trivial task and also most of the times enough is just not enough!

Here are some simple scripts for Linux to log dmesg continuously and dump into file and at the same time you can monitor changes in dmesg!

Give exe permissions to script and run as bellow,
$sudo ./ldmesg.sh

Now, dmesg is getting continuously logged in dmesg.log file in current directory. Next script needs to be run in another terminal tab/window which will monitor changes in dmesg (actually dmesg.log).

Give exe permissions to script and run as bellow,
$./mdmesg.sh


Image bellow shows dmesg being monitored.

For Android developers, here is ldmesg modified to use it over adb,
 
-- Cheers!!

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Linux Experience on Windows!

Yes, I love Linux and Windows too (yaah!..lets just say that!, as I use windows phone :)). Almost all engineers works most of the time on Linux and likes to fly VIM and similar editing tools. But sometimes sh*t happens and we forced to work on Windows and believe me it really feels like trapped in hell. Yes, I have been there, So here is your door to Heaven through the Hell!

Cygwin , Its your door way. It gives same experience as Linux shell. It includes most of the packages engineer/programmers need. Even you can ssh to remote Linux system using same command as in Linux shell, do you believe! and list goes long, Let curiosity be your guide!

Here are some basic instructions for setup...

1. Installation
 Download installer according to your system needs (32/64bit) and start installation.
 Just go through usual installation steps,

 

Next...Next...

Choose any site to download from...

 

Wait for a minute...

Now you need to search packages you need and mark them for installation. 

There long list but I'll install vim for reference.

Search for it...

 

 Mark VIM for installation and go next...

 

It will find package dependencies and start downloading it, give it a time...

 

Click 'Finish' and installation is done.

2. Running VIM in Cygwin:

Now, go to start menu and start Cygwin. It will open shell similar to Linux shell. Your root directory will be installation directory (C:\cygwin64\)

Now, you can put your vimrc in your $HOME directory (i.e. C:\cygwin64\home\user.name\.vimrc) and it works just perfectly.

Here is bashrc file in vim ($vim .bashrc)

Cheers!

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VPN Client for Linux Systems: Alternative for Cisco AnyConnect VPN Client

Hi,

Here is how you can connect to your VPN server without Cisco AnyConnect VPN client.

1. First install network-manager plug-in for VPN

 $ sudo apt-get install network-manager-openconnect  

2. Click on your network manager applet you will see  "VPN Connections" option, roll mouse over it, some options will pop-up, then click on "Configure VPN..."

3. Then click on "Add" to add new VPN connection, select VPN connection type "Cisco AnyConnect Compatible VPN (openconnect)" and click on "create". Window to configure new VPN connection will pop-up.

4. Then enter your VPN gateway and click save.

5. To Connect to VPN, go to network manager applet again, then "VPN Connections", it will pop-up VPN connection you just created, click on it.  Then VPN connection window will be up, just click on connect icon to establish VPN connection.

Done!
cheers!!

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