A bit about tech interviews

This Article is written by the founder of CareerCup but what I found most interesting is the first comment made on this article. I would say this is something a techie must read. In my personal experience also, I also agree with the commenter.

system calls

If you are familiar with programming in C with linux /unix systems, you must be aware of that most of the function calls internally calls the system calls to serve the purpose. System call is nothing but invoking the code written in kernel to serve the specific purpose being it the memory allocation, printing on your screen or asking for the input from your keyboard. Ever wondered what all happens when you call printf. Here is the anatomy.
When you call the printf, your compiler looks for its definition in glibc library which is automatically included in your library path. glibc implementation reformat the arguments passed to the function and then pass these arguments to the write() system call. Now there are a lot of things happening before the code of write() from kernel gets called.
Each system call in kernel is implemented by function named sys_SystemCall where SystemCall is the name of your system call say for write(), it is implemented as sys_write(). System calls are architecture dependent and hence each of the architecture has its own set of system calls and their implementation. Once booted into the kernel, kernel maintains a global table of system calls sys_call_table where each of the system call is assigned a no.
When a system call like write() is made, some assembly code gets executed which does the following:
set the system call no. in register EAX
store the parameters in EBX,ECX,EDX,ESI and EDI registers, for more than 5 parameters pass the address of user space stack using either of the register
issue interrupt $80 (software interrupt)
When the system sees the interrupt, it stops doing what it is doing currently and query the interrupt descriptor table (IDT) using IDT register. In the entry phase, assembly code gets executed which saves the value of registers and mark the system to be as running in kernel mode. IDT contains a mapping of the interrupts with address to their service routines. $80 maps to the code of system call handler routine. This routine gets executed which examines the value in EAX register and queries the sys_call_table for the address of corresponding system call implementation. It then loads and executes the routine. Return value of the system call gets stored in register EAX.
Once the system call completes, system returns from kernel mode to user mode and depending on the scheduler, process resumes the execution or waits for its turn in the scheduler‘s wait queue.

Raring Ringtail Ubuntu 13.04 released

Grab the desktop version of the ISOs from the below links
32 Bit ISO
64 Bit ISO

World of Today

I am fed up with the news of crime all over the world. Terrorist attacks, Nuclear threats, Internal Mobs. Rapes, Burglaries, Killings. What is happening all around. Why not just everyone go happy and live peacefully. All is due to nothing but a lust for the power right from the individuals to the nations. Nobody takes away anything from this world then why all this. Why cant this earth be a happy place. Tonnes of questions and lots of frustration. Does somebody have an answer?

Praise to China

How aware a government can be? Visit this link.
Being the largest market of smart phones, Android shares a market share of 90+% in China. 90+ is quite a huge number. Android is no doubt a very good product but for the betterment of technology and also to avoid the future effects of monopoly, its always necessary to have a good competitor. It was good to read that their IT ministry keeps up with the market trends and presents such kind of research papers and motivates the industry towards a better technology. I can never imagine such kind of motivation in India where politicians are more worried about their chairs than the country’s growth. Where this step shows why China is more technologically advanced, we Indians take pride in being consumers or following the world when it comes to technology. I know that many people will come up with a lot of Indian names who have breakthroughs registered against their names but those are very sheer numbers if we compare it against the others.
Being a leader is not that tough job if we have the right kind of motivation and energy.

IPL 2013

This IPL 2013 has been quite a good time pass with a no. of interesting games. Its good to see some low scoring games with such a fighting spirit. After coming back from office, its a good source of entertainment. Sometimes the games are so good that it won’t let you do anything else even if you want to do it badly.
Though one thing is missing in this IPL. This time not many such players has emerged from the pool as there were in earlier versions. All those names who made it big in some of the previous versions likes of Abhishek Nayar, Manish Pandey, Saurabh Tiwari seems to be hidden in the crowd. Teams having the big names looks to be a primary choice of anyone with an exception of Rajasthan Royals which is playing like it played the first season.
Teams which are to lookout for in this season are : MI, RCB , KKR, RR and all time favorite CSK. One can expect some upsets from Pune Warriors India, Sunrisers Hyderabad and Kings Xi Punjab. One team whom no body would like to back this time will be Delhi Daredevils. Sehwag‘s struggle and team’s dependency on warner who is also miserable in the tournament is hurting them badly.
There have been few highlights of this season which includes Two Ties from RCB, Gambhir Kohli aggression, Dhoni’s tweets about SRJ, Amit Mishra’s Third Hatrick . Overall this IPL adds another milestone in IPL’s success history

Fuduntu call it a quit

http://ostatic.com/blog/oh-no-fuduntu-calls-it-quits

Fuduntu , a distro which lies somewhere between Ubuntu and Fedora is calling quits.

Saving Open firefox tabs as a session for later restore

I like the feature of firefox where one can restore the complete session after a restart of browser however that only restores the last open session. Many a times I do open so many tabs related top some topic and keep them open to read later. But sometimes when window gets closed accidently and if I forget to restore the session next time, its a painful process to goto history and find out the ones I need.
Here is a trick to overcome this pain. For an open session, right click on any tab and click “bookmark all tabs”. Save it by some appropriate folder name . Now whenever you need this session, goto that folder from bookmarks and right click on it. Choose “Open all in Tabs”.

Thats it. Enjoy Firefoxing.

Some quotes on jainism from personalities around the world

“I adore so greatly the principles of the Jain religion, that I would like to be reborn in a Jain community.”
– George Bernard Shaw

“I say with conviction that the doctrine for which the name of Lord Mahaveer is glorified nowadays is the doctrine of Ahimsa. If anyone has practiced to the fullest extent and has propagated most the doctrine of Ahimsa, it was Lord Mahaveer.”
– Mahatma Gandhi

the eternal mystery of the world is its intelligibility. True religion fastens to this element of intelligibility and creates a system of thought and action which leads to true harmony and bliss. And it is indeed so with Jainism.
– Albert Einstein

“There is nothing wonderful in my saying that Jainism was in existence long before the Vedas were composed.”
– Dr. S. Radhakrishnan, Vice President, India

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Four little things that shaped India: Part 1

A deep dive to the Indian History

The Kaipullai's Vetti Thoughts : The outer playground of my inner devil

History books tell us that only events of tectonic magnitude, like say the Vasco Da Gama journey, shapes the history of the world.

This post is not about events like that.

This post is about some random little incidents from Indian history. Incidents, which are inconspicuous when viewed in isolation. So inconspicuous in fact, that they were eliminated from our History books.

Can’t blame the textbooks though. I mean what is the worst that they could have missed by not mentioning a single arrow, a pencil stroke or a nod of the head?

It is not as if these things influenced our History.

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