Samar and his thoughts

@breakfast

2010-07-04T22:07:00.001-07:00

It is Monday morning and a holiday. I got up early and was planning for breakfast. As you all know these are very difficult job for a bachelor. :-( The popular breakfast here is idly,Vara and Dhosa which i don't like always. I looked for some interesting breakfast. But what to do? Ok, lets try it. I went to some fruits shop, brought mango/apple/pomegranate then looked for brown bread and then Boost (the secret of my energy). I went back to home and started the real job of preparing the breakfast.(A tough job indeed :-( ). Now have a look how i prepared the breakfast.

A thought on Relationship

2010-06-09T06:46:00.000-07:00

I love you.

I love you..

I love you...

.. hey man ! wait wait. I am not proposing anyone through my blog. (Really?)

Rather it is the most frequent sentence used among teenagers in India.These words are primary steps to start any interesting relation ;-).

let's dig into this relationship chapter.

[Story 1]

First day of XYZ collage of Engineering. (Math classroom)

All good looking girls sat in first few chairs and all guys were back bench er.

A teacher came and started the theory of probability. As you know the theory of probability has always probability of understanding.Very few understood the theory. At the end of the class everybody started moving to corridor for next class. Suddenly some voice was heard. "Hey Sidhardh! do you have notes on the probability? Do you help me to understand it". A guy fell back from the group, waiting for the source of voice.

After few days the couple find their recognition in college. :-)

[Story 2]

First day in office. Breakfast time. There was long queue in front of the breakfast counter.

A guy, standing in the queue, looking at someone, made a comment. "These guys are delaying too much to wait. We should complain to higher authority." The reply came "Certainly. We should complain it. Do you know the contact number?". Conversation started...

After few years later, common friends find them as married couple.

There are lot of incidents through which people choose their life partners. To find life partner, the sentence "I love you" plays an important role and thus the "Love Marriage" signed it's signature.

People who did love marriage gives lots of arguments. Lets listen some of them.

"In love marriage, you can judge a person over a period time. How could you get married to someone whom you don't know. You can't take life long decision in just few hours."

"Love marriage is sooooooo sweet. Everyone should do Love Marriage!"

"Love is the strongest sentiment that keeps you young in your relationship. Love marriage is the best thing in this world!"

"We live in 21st century. We should have freedom to choose our own destiny and Love Marriage is part of it."

OK, friends. Lets do an open heart surgery of "Love Marriage" and "Arrange Marriage".

Marriage is an event to start a new relationship.Did you ever think about why most of us expect the marriage to be a memorable one? Can anybody thought of his or her marriage to be a silent simple court registration? It does not matter whether it is a "Love Marriage" or "Arranged Marriage".The answer would be 'NO'.

Some people would say ! "Hey stupid. Didn't you heard of Living together in 21st century?"

My answer would be "Hey dude! do you know the difference between Living together and a Marriage?"

You would say "Live-together is a modernize concept. If you like someone, start living with him/her. No need to do marriage. If you don't like him/her .. just leave him. No legal botheration. It is a concept from West and we can learn a lot from them.

Well friend! whatever you told is correct. It is human-mind generated. Let's looks at it from a different angle. Like in "Love Marriage" a couple is known to each other in living-together relationship.

One can admit that it is not possible to know 100% of a person in just a 4/5 years of relationship. Thus any wrong thing could happen after the marriage as well. Here 'Living relationship' comes into rescue. Here you can leave the partner. If it doesn't happen then you can live happily with your partner like in Marriages(Doesn't matter if it is a Arrange Marriage or Love Marriage)

Thus an event of marriage has a social touch along with legal one. If some misunderstanding happen after marriage it is the social and legal bond that make you compel to adjust with the situation and will taught you

the biggest lesson of life "You could not get whatever you expect." This lesson couldn't be taught in "Living relationship", thus making the divorce rate high.

So friends in "Love Marriage" you could know a person before marriage but could only understand him/her after marriage and thus it is not a different from arrange marriage .. where we start from ;-)

[Disclaimer: It is just a thought. It is not for the purpose to hurt anyone]

A spiritual thought

2010-05-23T02:07:00.000-07:00

A person enters into his Boss's cabin. The person was very much thrilled as he was expecting his promotion in the meeting.

Boss: Hey dude! What's up?

Person: Everything is GOOD.

Boss: Gr8t man! I have another good news for you. You are being promoted to Manager designation of India.

Person: Wow! That's great news.

Boss: So... How do you feel?

Person: I am on the TOP of everything.

(Boss gives a smile ;-) )

Boss: Gr8t. Now listen! The upper management expect you to work harder and generate a good revenue for the company.

Person: Sure! I shall definitely try my best.

Boss: Don't try. Just make it.

Person: SURE

That person leavs the cabin and went to his cubical. He was congratulated by all his colleagues. Some of them asked him for treat. He promised.

He came home and told the news to his wife. Both of them were delighted. They went out and finished dinner at some costly restaurant. After that they went out for a long drive at night to some unknown place...

[A few days later ...]

He came back from office. The day was very much hectic. He was very much tired and felt sleepy. He sat down on a sofa, relaxing himself in front of the television. Channels were browsing to find out some good interesting entertaining event. Suddenly there was a BREAKING NEWS flashed in some news channel. American share market(NASDAQ) has crashed. Some company declared bail out. Every share price was going down. It was an evening in ASIA.

It is yet to fell the heat. He tunned the news channel. Tried to understand what exactly happened? How it will effect his job and his company and more importantly about the future. EMI for the new flat of worth 40 lacs, not finished yet. In addition to that car loan is still pending...

On the very next day morning , he woke up , prepared himself for office and started driving for office. He was expecting something unusual at office. He entered his decorated cabin, specially designed for managers. Opened his computer. A meeting invitation flashed. A meeting with his higher authority at 10:30 am. He felt the bad smell.

[@10:30 meeting room]

Boss: Hey dude! What's up?

Person: GOOD.

Boss: Gr8t man! I have another news for you. The higher authority has decided to close down the India operation within next 2 months. Please convey this news politely to your subordinates. Hope you can understand our situation and management is very much sorry for that.

Person: OK

Boss: Thank you very much.

The person left the office at evening and came home. Very much depressed and frustrated. He don't have any job right now. There is no money flow. Life seems to end ...

For next few days he tried to find out another equivalent job. Recession already hit the market. Thus finding a job in this market was really difficult. Thus a new job, looks illusion to him. He broke down. Want to escape from life. He asked himself... "What life has given to me?" "Why these things only happens to him?"

He looked around and saw some people were driving Mercedes car. He was depressed. "To escape from the situation suicide is the only option"... he thought.

He went ahead to commit suicide. On the way he met one of his colleagues. The colleague was smiling despite of his job loss.

Person: Hey..why are you smiling? you lost your job. Isn't it?

Colleague : Right, There is no harm in smiling. :-)

Person: Correct.... But...

Colleague: Friend! Happiness and sorrow are part of real life. If we can accept a good moment, we should accept the hard moment as well. We can't escape from this "Rule of life".

Person: That means we don't have to do anything for ourselves? Does everything happen automatically?

Colleague: No. We have to try to achieve what we dream for. But it is not guaranteed that we will achieve that. Rather we have to be prepared for any kind of outcome. We can do karma but we can't decide result. It is our job to keeps on working ... keeping smile on face :-)

Person: Sounds good. Let's go to your home...

[A few months later]

Morning 8:30 am

A TV switched on. There was another breaking news. "Recession hit market seems to recover... Govt has declared stimulant packages..."

A phone ringed . He picked up the phone. A voice was heard from the other side of the telephone wire. "We are looking for some experience manager for our firm. Would you like to come for an interview.."

After a small conversation he put down the phone and came to window side.

A ray of SUN smiles on his face....

How do i write blogs

2009-06-18T09:30:00.001-07:00

I am a blogger. I write blogs everyday... well truly,... every month... strictly speaking at least once in 2 months... well,surely once in six months :-)
All most everyday i sit down to write something.. something which could be published in blog ;-). I scratched my head for finding out interesting topics to write in blogs so that you people read those bullshit and praise me :-D I put on my computers, opened a notepad and tried to write something...sommmeee... thing ... and then either i felt sleepy and dipped into Harry Potter's world or i started counting seconds :-(.
Though the above story was not always true. A day when there was no power at evening... in the middle of darkness... a mild breeze was blowing..., putting a candle on the study table i started writing blogs. The darkness gave me the power of thinking, the breeze made me relax and the light gave direction to write blogs. .... i went into a world of unknown, a world of dream, a world of thoughts. I started thinking about INDIA, Mr Gandhi, OBAMA, and then ..... suddenly to Bebo(karina Kappor), Bipasa, Katrina ..... ;-)

All of a sudden door bell rang... call for dinner . Everything (sweet dream) goes away ... :-)

Guys, in short...this is all about my blog writing. :-D

My first achievement in Life

2009-03-04T04:56:00.000-08:00

It was 1990-91. It was a year from my childhood. Sports were my favorite events on those days and study....you can guess, my worst enemy.
Frankly speaking, i was a much favorite player in football tournaments. In those days i played like Mara Dona... Believe me, i am speaking truth. :-)
It was assured that the team, having me as member was going to win the game. I still remember, when i took shots, no goalkeeper can resists my shots.
Those days were really awesome. One day i was returning home after wining the game as usual, chatting with some of my friends. Suddenly i saw one of my friends with new bicycle. It was quiet dazzling. I can still remember it was "Hero Hansa". It was a new trend in bicycle. It was blue in color, having fancy look with light in weight. In those days, those who had the one were on different status.:-) Like "Mere pass bicycle he, tumhare pass keya he".... (little stupid na !!) More over the fancy Cycle ...yes that bicycle was the key to talk to any girl...and i didn't have that :-(

Immediately i had decided to ask for the similar bicycle to my parents. I came home and went to MOM. “Ma Ma amake natun cycle kine dao na!!”. My Mom scold me ("PORTE BOSO") for not preparing my home work for the next day in school and said a big "NO" to buy any new bicycle. I was hearted. I went to the study room, open a book but could not concentrate. Then i went to my DAD. I did the same repetition. DAD looked at me, thought something and spoke out… "If your are able to qualify the admission test of Asansol Ramkrishna Mission then a new bicycle will be yours !!"
He stopped and looked at me. I had no words.(As it was quiet well known fact that breaking the admission test of R.K.M was not a matter of joke in those days and i was studying in some ordinary primary school. The R.K.M School is renowned in Asansol (till now).)
The dream of having the new bicycle was about to dismantle. I could not found any way out but to accept the challenge of breaking through the admission test.
Though i want to make sure whatever i heard, was correct. I replied with "If i cleared the admission test, you will brought me a new bicycle.. pakka??". Dad said "YES"!! From that day for next one year i forget everything, my game- football, Mara Dona... everything, only concentrated on study. May parents helped ma a lot on those days. Dad taught me Math’s and Mom "Bengali". I still remembered those hard working days. Those are golden moments to my life.

Finally the day of admission test arrived. On the day of examination i felt little nervous. I took the entry in examination hall. The examination hall was huge. It was the month of April and there were no electric fans in the Hall. My seat was just beside the window, the large window, i never saw such huge window and just above the window there was a photo of "Sir Swami Vivekananda". I closed my eyes and prayed to god for new bicycle :-). Then the bell rang and the examination started. The examination duration was 3 hrs. I could not make out how the long 3 hrs duration went away. An instruction came from the invigilators... "STOP writing". The examination ended.

I came out from the examination hall and found my parents were waiting eagerly for me. They asked, "How was the exam??" I smiled and said "DARUN"...
The result came out within few days and I, yes, yes, cracked down the admission test. That was my happiest moment in my life. My parents were really happy in that moment. I jumped and went my Dad.. "!!Dad new Bicycle.!!" Dad said "Tathastu" (As you wish)

I got the new bicycle as my first achievement. It was really a memorable day in my life.

Static binding vs Dynamic binding

2009-01-27T02:35:00.000-08:00

Probably most of us, studied the Static/Dynamic binding in compiler design course in Engineering. For me i did not understand that time ;-), though i understand now and shall explain it with an example so that guys with similar IQs like me can understand before coming out of college :-) .

Lets try an example of C++ program.

Class A{

public:
virtual void foo(){ /* ... */
};

int main()
{
A a;

a.foo(); --->> What do you think??

return 0;
}

During compilation, compiler has enough knowledge about the data type "A" and it's object 'a'. Hence when you write compiler can readily identify the foo function during compilation time and thus binds it with object 'a'. This is called static binding.

-- So what's the Dynamic binding??

Lets consider the code with some modification.

Void foo1(A &ref){
// ref.foo(); --> Is this something different from static binding??
}

Void foo1(A *ref){
// ref->foo(); --> Is this something different from static binding
}

int main()
{
A a;

foo1(a);
fooe1(&a);

return 0;
}

So during compilation time the function body is not executed. It is executed during runtime. Hence when we are specifying &a or *a , the object type is determined during runtime. Thus calling a the function 'foo' is fully depends on runtime. Thus it is dynamic binding.

Do let me know if you have any query. ;-)

College reunion

2009-01-17T05:17:00.000-08:00

It is nearly a period of 5 years of time .. when i passed out from an engineering college. A college of my studies , my place of fun and temple of knowledge .. It was nearly an obsolete picture during these five years of time. Almost forget everything..starting from college faculties to the memories of the time, spent in computer labs. A computer lab where i spent 99% of time in 8th semester , engaged in false attempt to innovate any new network protocols. Every day was my HACKED DAY in the college,specially in computer labs. I used to download the Linux source code, tried to compile , faced a lot issues, asked those faculties, did not get any satisfactory answers and thus finally abusing them. ;-) Later in course of time i learnt to browse the Linux kernel codes and then understood various aspects of Linux kernel. Still i am learning the Linux kernel, It is so big and complicated that i could not able to understand the 100%. :-D Now i can understand that was not the fault of our faculties :-). All these were history in time. A lot of things happens during these 5 years.. I came out of college , joined IXIA, developed different mail protocols, then moved to HP, started to look into the SNMP protocol and thus the OpenView product...times were running smoothly ..no hiccups.

Suddenly my mobile rings. I saw an unrecognizable number. I tried to ignore it. It again rings. This time i picked up the phone. A voice hit my ear curtain.. "Samarjit da chinte parcho??" I didn't recognize the voice. I started murmuring ... then the unidentified voice introduced itself to me and finally i identified him as "SUMAN"(A junior of 2005 batch from my college). Suddenly all college images bubbled in my mind. I felt emotional. He invited me for college reunion.
A reunion of all AEC student, here in b'lore at FORUM mall. It was really surprising to me. I was headly aware of any AECian, present in B'lore :-(
(SORRY)
Today is the day of college reunion. I just came back after attending the reunion party... hold on guys.. there is no liquor in the party :-0. It was merely a vegetarian party, followed by a bengali adda in some park. A meet with lot of old friends brings me a new wave length in my life. It was a nice experiance, sitting in grass and chatting with old friends. Everyone talks about their experiences during this 4-5 years and all of a sudden i was started feeling, we are doing chat on the ground of JUBILI .. (a park just in front of our college :-)).
Seriously it was a nice experience. The adda was continued for 3 hours. Then we dismantled our adda session, promising to arrange similar addas in the interval of 3 months. ... :-)

Last but not the least, we should thank SUMAN , for his immense enthusiasm in arranging AEC reunion.

'Mumbai 26/11 attack' - A game of politics

2009-01-02T18:53:00.000-08:00

The following news has been published in Yahoo ...

read out ...

In his interview to Time magazine on December 29, 2008, President-elect Obama has spelt out his foreign policy priorities. He has said, among other things, "Managing a more effective strategy in Afghanistan will be a top priority. Recognising that it is not simply an Afghan problem but it's an Afghanistan-Pakistan-India-Kashmir-Iran problem is going to be a priority." It is strange that neither terrorism nor jihadi extremismÂ figures in this formulation. Prima facie it would suggest that the incoming administration looks at the issue as a regional interstate problem.

Let us remind Obama and his team that this phase of the Afghan problem started with 'Operation Enduring Freedom' in October 2001 following the refusal of the Taliban regime in Kabul to surrender Osama bin Laden and Al Qaeda cadres. The Taliban regime was cleared out of Afghanistan by the US Special Forces and troops of the Northern Alliance supported by US air power. As the operation was coming to a close and Osama bin Laden and remnants of Al Qaeda wereÂ cornered in the Torah Borah mountains, terrorists with links to Pakistan's ISI attacked the Indian parliament. That compelled India to mobilise its forces on the border. Pakistan countered that move and Â by vacating its western borders permitted Al Qaeda and Taliban leadership to find safe havens in Pakistan. It is now quite clear that the attack on the Indian Parliament was a provocative ruse to trap India into a military move which would justify Pakistan's convenient troop withdrawal.

The same strategem has been employed in November 2008. The Mumbai terrorist attack was to provoke an Indian military response and provide an alibi to Pakistan to withdraw its forces from the western border and enable a Taliban surge into the tribal areas and Afghan territory to preempt and wreck the proposed US surge strategy. In 2001-2, the attention from Al Qaeda and Taliban consolidating themselves Â in Pakistan was diverted by raising Indo-Pakistan tension. Thereafter Iraq preempted all US attention. Now when the attention of US and the NATO are refocussing on Afghanistan, the same diversionary tactics are being employed.

ManagingÂ a more effective strategy in Afghanistan, as the President-elect desires, should start with a review of what happened in the last seven years in the region. While Pakistan received over ten billion dollars of US aid, Al Qaeda and Taliban leaderships were safe and sound in Pakistan and expanded their activities. Prime Minister Gordon Brown made it clear during his recent visit to Pakistan that in 75 per cent of the cases of terrorist activity in UK, links were traced to Pakistan. In 2002, for the first time religious parties won elections in Northwest Frontier province. It is widely accepted that those elections were rigged by the Inter-Services Intelligence under the Pakistan army - a sure sign of General Musharraf's lack of sincere commitment to the war on terror and religious extremism. In the seven years when Pakistani army and the ISI wielded power publicly, the Taliban and jihadi organisations were allowed to gain in strength. Mullah Omar was living openly in Quetta and building up the Taliban and providing inspiration for the Pakistani Taliban built up in the Federally Administered Tribal Areas.

The spirit of TalibanisationÂ engulfed the 'Lal Masjid' madarassa in the national capital, stormed by the Pakistan army. That was followed by a number of suicide bombings in various parts of Pakistan, including Benazir Bhutto's assassination and the Marriott bombing. Today Pakistan's government and civil society rightly claim that they have become the victims of terrorism. The rise in terrorism within PakistanÂ took place in the last seven years when the army was in power.

The former CIA analyst, senior National Security Council staffer under President Clinton, an Obama campaign advisor, Bruce Riedel sees the terrorist networks' base in the mountains of Pakistan as America's greatest threat. In his forthcoming book The Search for Al Qaeda, he speaks of the Pakistani government's savvy campaign under General Musharraf to fleece Washington for billions of dollars even as it allowed Al Qaeda to regroup in Pakistan's tribal lands. Riedel says in an interview to The New York Times, December 21 - "we had a partner that was double-dealing us.Anyone can be snookered and double-dealt. But after six years you have to start to figure it out."

According to him, the terrorist networks believe that the 'bleeding wars' offer the best opportunity to defeat the US. Winning in Pakistan , says Â Riedel, requires a tough love approach: overhauling the military aid to Pakistan and cutting sales of the big ticket weapons it has used to keep pace with India. It was Washington's too cozy relationship with Musharraf's military government that fuelled the intense hatred for the US in Pakistan. He cites polls that more Pakistanis blame the United States than either India or Al Qaeda for the recent surge in violence in the country and adds that 'any time in Pakistan where Â more people blame you than India for the country's problems, you are in trouble"

The terrorist attack on Mumbai ,followed by Â false allegations of India escalating tension, publicity about possible Pakistani troop transfers from the western to eastern border, destruction of convoys intended for US forces in Afghanistan at Peshawar and the latest stoppage of US convoys on the excuse of fighting militants in the Kabul Agency are all ruses practiced over the long Musharraf years, now being repeated by General Kiyani. The continuing double-dealing is based on the basic belief shared by the jihadis and the Pakistani Army and Intelligence that, as Riedel points out ,'bleeding wars ' are the best way to defeat the US, as happened with the much larger Soviet forces in Afghanistan supported by a more effective Khalq-Parcham government in Kabul. Correctly understanding why a war fought Â by the US Â over seven years has not only not produced any successful results but has increased the strength of the adversary in the territory of the ally, Pakistan should become the foremost priority of the Obama administration.

Pak hacker attacks E Rlys site, threatens cyber war on India

2008-12-26T10:40:00.000-08:00

Kolkata: In the first instance of cyber attack on Indian government websites, the attack on Eastern Railways site on Wednesday popped open vulnerability of government websites in the country.

While Eastern Railway took almost two and half hours to restore the site to normalcy, visitors to the site continued to be attacked by Trojan virus. ER officials could only primarily trace the roots to Toronto in Canada after repeated top-brass meetings all through the day.

As spotted by FE in the morning, the official site of the Eastern Railway-www.eastern railway.gov.in—was hacked on Wednesday. When opened, the scroll on the site— which normally consists of official announcements—had unusual notes. The first note read: “Cyber war has been declared on Indian cyberspace by Whackerz- Pakistan (24 Dec-2008).” This was followed by two other notes: “Indians hit hard by Zaid Hamid” and “We are f**ked up Indians. You are hacked.”

When clicked, the scroll opened into a new window which claimed that ‘Mianwalian of Whackerz” has hacked the site in response to the air violation of Pakistan. It also claimed that it will continue to hack more Indian military and government sites. The threat note also claimed that servers of Indian financial institutions will also be hacked with the help of the group’s members working in computer departments of “foreign companies”. Data belonging to “Indian nationals (only Hindus)” will be destroyed eventually, it added.

Another threat note asked the visitors of the website to watch the real Indian conspiracy in Mumbai attacks on the website-www.brasstacks.pk. Brasstacks claims to be “a unique Pakistani think tank devoted to the study of regional and global political events and their implications for Pakistan’s security and interests.” The note ended with the slogan “Long live Pakistan”.

The third note, which showed the hackers’ apathy towards India, Israel and USA, challenged Indians to save their ‘motherland’ from turning into pieces.

When contacted, ER officials seemed unaware of the entire incident and the site remained as it is for almost an hour, till 11.40am, after which ER blocked it. The website resumed to normalcy after 12, when the threat notes in the scroll as well as in the news and events section were removed.

“Our sites have cyber security certificate from US-based Thawte,” said an ER official. “We have informed the service provider and will get a detailed response from them only after 24 hours,” he added.

SHOW me the CODE

2008-11-13T10:29:00.000-08:00

Hey guys..
foss.in is in air. catch it and be a part of open source movement.
Come lets join and rock the world!!

N.B. click on http://foss.in

2008-11-05T02:21:00.000-08:00

Prog:
main()
{
printf("%f",7/2);
}

7/2 is 3 right?? now 3 will be interpreted as float for printf. Now for each machine architecture the float representation is different.It is not known to us how the float value has been interpreted(at least not to me ).Hence any interger value when interpreted as float it is undefined what the value will be printed !!

Prog:
main()
{
int i=-1;
+i;
printf("%d%d",i,+i);
}

This program is quite silly one. Here (+) operator will act like only +2 i.e. to denote a +ive value. Hence when you do +i that means +(-1) which is as same as -1 only.Hence the output will be -1-1

2008-11-02T04:12:00.000-08:00

PGM 1
main()
{
int i=-1;
+i;
printf("%d%d",i,+i);
}

PGM 2
main()
{
printf("%f",7/2);
}

Did anyone know, what will the output of the above 2 programs? Explanation is required.??

More digging into physical memory layout

2008-08-05T05:37:00.000-07:00

Well, we have discussed the physical memory layout in my last blog.We have understood that among the first 640KB some areas are not usable. Lets try to find out the exact memory count which is not usable by the operating system, rather, that area is used by ROM and IVT (interrupt vector table).

Lets try to find out the first 31kb of memory. We know the memory layout is something as follows.
....
31Kb 0x07c0:0000 |-->>07C0:0 Boot code is loaded here.
0 Kb 0x0000:0000 | Working RAM LIMIT start +System information like
(Interrupt vector table)

If you tried to find out the exact memory usage by the BIOS, we will find that
the data is allocated at the maximum of segment number 0x0070:00 which is less than 1K.
[REF]
http://www.frontiernet.net/~fys/rombios.htm
http://heim.ifi.uio.no/~stanisls/helppc/bios_data_area.html

Hence rest of the memory up to 640KB can be used by the Operating system. In fact DOS2+ used that area.

!!! Lets find out how Linux treats those memory !!!

Linux always believes in cooperative environment. It's does not try to eat
market share of other. So what does the Linux do in case of memory
utilization?

As we all know that the physical memory is logically divided into chunks
called "page frame". 1 page frame == 4KB . As all system data require
approximately 1KB, Linux tried to mark the first page frame as not usable.
The rest of the pages upto the page frame number 0x9f(i.e. 640 KB) is
marked as "usable" and page frames from 0x9f to 0x100 (UMA, 1MB) are
marked as "not usable". Then the kernel code is loaded in the first byte of the
second megabyte of the physical memory. The starting of the kernel code is
identified by the symbol "_text" and the end of the kernel code identified by
the symbol "_etext". All these symbols can be found in Symbols.map file after
compiling the kernel.

Lets try to visualize the memory layout from the point of view of Linux 2.4 OS.
[REF: "Understanding Linux kernel."]

Physical memory layout when the processor is in REAL MODE

2008-08-03T11:34:00.000-07:00

As i promised earlier we will discuss the pictorial view of the physical memory layout in real mode. We need to keep in mind that this physical memory layout is totally different from the virtual/linear memory layout either in kernel mode or user mode processes.

The linear address space of a process is divided into two parts:
Linear addresses from 0x00000000 to 0xbfffffff can be addressed when the
process is in either User or Kernel Mode.

Linear addresses from 0xc0000000 to 0xffffffff can be addressed only when
the process is in Kernel Mode.

-- We will discuss on this topic later in details.--

Lets try to visualize the physical memory layout:
---------------------------------------------------------------------------------

1 Mb = 0x10000:0000

1 Mb-1 = 0xFFFF:000F End System BIOS area
960 Kb 0xF000:0000 | = 128 Kb
896 Kb 0xE000:0000 Start System BIOS area

896 Kb-1 = 0xDFFF:000F End Expansion card BIOS area
832 Kb 0xD000:0000 | = 128 Kb
768 Kb 0xC000:0000 Start Expansion card BIOS area

768 Kb-1 = 0xBFFF:000F End Video RAM
704 Kb 0xB000:0000 | = 128 Kb
640 Kb 0xA000:0000 Start Video RAM

640 Kb-1 = 0x9FFF:000F| Working RAM LIMIT ENDS
576 Kb 0x9000:0000 |
512 Kb 0x8000:0000 |
448 Kb 0x7000:0000 |
384 Kb 0x6000:0000 |
320 Kb 0x5000:0000 | = 640 Kb
256 Kb 0x4000:0000 |
192 Kb 0x3000:0000 |
128 Kb 0x2000:0000 |
64 Kb 0x1000:0000 |
31Kb 0x07c0:0000 |-->>07C0:0 Boot code is loaded here.
0 Kb 0x0000:0000 | Working RAM LIMIT start +System information like
(Interrupt vector table)

To know more about BIOS service routine table(i.e. Interrupt vector table) click on the following link.
!!URL!!
http://bioscentral.com/misc/biosservices.htm

If you guys have any queries do let me know , else i will think more on this memory layout and if i found something interesting i will discuss it here.

Good night to all of you.. Going to sleep now ....

Find hard to understand the BIOS call sequnce during Booting a PC

2008-08-02T11:35:00.001-07:00

Hum .. Today is 3rd August 2008, My last blog was 19th July, was trying to build custom kernel without success. Then i thought of making some documentation on Linux system call sequence. I started and confused in understanding the protocol initialization during startup time. Hence i jumped from system call sequence to system booting up process and decided to create documentation on PC boot up sequence.

This time i am strongly determined of doing the documentation. I downloaded the Linux kernel code 2.4.19 and started looking into it.Soon i learned that "I am very confuse guy who didn't understand anything except computer/linux assembly and machine code." -- Got depressed very much(Probably no one will dream me as BF ;-))

Meantime 7 bomb blast rocked the city of Bangalore, and i got depressed again feeling the insecurity.Then i don't know , all of a sudden again i got interested in browsing Linux kernel code.

-- Ha, haha this time success smiles on my face.I was able to understand the majority of the bootsect.S code, but still there was something missing.After some time i realized that it was the concept of memory management. I started looking into the memory layout during the PC bots up and finally came up with the following concept.

As the system boots up the real mode addressing works, thus specifying all address in seg:off format. The seg:off format can be converted into linear address by the rule (seg*16+off) == Linuear address.

Memory Layout overview:
------------------------------------------
1) Conventional Memory:
2) Upper Memory Area(UMA)
3) High Memory Area (HMA)
4) Extented Memory Area (EMA)

1) Convetional Memory:
-----------------------------------
The first 640KB of system memory is known as "convetional memory".In the historic age DOS and some it's driver code used to run in this memory region, thus the naming convention.
Linear address range : 0x00000 to 0x9FFFF
Segmented address : 0x0000:0 to 0x90000:FFFF

For more infos: Please read
http://www.pcguide.com/ref/ram/logicConventional-c.html

... Feeling sleeping today, leaving right now, tomorrow we will discuss rest of the memory layout. :-)

After 12 hrs of rest in the evening of a friendship day, i woke up to complete the blog ;-).

Ok last, we have discussed about the convetional memory layout. Lets talk about the "Upper Memory Area" or (UMA)

2) Upper Memory Area:
-------------------------------------
The next 384 KB starting from the address 0xa000:0 to 0xFFFF:000F(or 0xA0000 to 0xFFFFF in linear address format) are supposed to be UMA. These memory range has been used for VIDEO RAM/ SYSTEM BIOS AREA/ Other Expansion CARD BIOS area. Remember when the machine is switched on the IP is set to the address as
CS:IP = 0xF000:FFF0
(Don't get confused 0xF000:FFF0 and 0xFFFF:000F --> Limit of UMA)
Means when the machine switched on the first instruction it tried to read from UMA.
More over we need to keep in mind that in UMA area some ROM addresses were being mapped in to the RAM and thus those addresses are READ ONLY.
We will talk about later while discussing the overall memory layout.

With the end of UMA the first megabyte of the memory layout ends here.

3) High Memory Area (HMA)
--------------------------------------------
The first 64KB(less than 16 bytes) of the second megabyte of the sytem memory. Technically this 64KB of memory is part of "Extended Memory Area"(EMA), though the difference it this part of memory range can be addressed when the processor is in real mode which makes it different from the rest of the extended momory.

Wait a minute....

Lets think about "How this memory range can be addressed by real mode??"

yes.. Any one ?? Besically i am a dummy guy.. never understand anything in a single shot...

Proof of Thinking 1 :
----------------------------------
We have 16 bits for SEGMENT addressing and another 16 bits for OFFSET addressing while the processor is in REAL MODE. Hence all possible combination are 2^16 x 2^16 = 2^32
As we know 2^20 == 1MB (First megabyte of the physical RAM ) the rest of the address i.e. 2^12 should be available as "High Memory Area"(HMA).
... Wait wait...
2^12 is 4KB but we were talking ablout 64KB as HMA?
?????????????????? What happend wrong ?????????????????????

Proof of Thinking 2 :
----------------------------------
Lets think in different manner. We know that Upper memory area ends at the address 0xFFFF:000F(Upto this address we already covered 1MB of the physical RAM). Now consider the address range 0xFFFF:000F to 0xFFFF:FFFF.
All possible combination is (2^16 -16) as we have started from 000F.
2^16 == 64KB. Finally got it.

4) Extented Memory Area (EMA):
---------------------------------------------------
This is the memory region above the High Memory Area until the end of the system memory.To use this memory region OS needs to be boots up in protected mode as no real mode addressing can access the memory region.
Extended memory is found from address 10FFF0h to the last address of system memory. (Technically, the high memory area is part of extended memory, it all depends on how you are looking at things).

We will talk about the memory layout in the pictorial manner in the next blog.
Good bye for now.

Hard to build Linux kernel 2.6.26

2008-07-19T10:25:00.000-07:00

My interest in Linux kernel has been revamped after attending a training session on "Linux Kernel debugging" from "arts-lab.com". Hence i have downloaded the latest Linux kernel 2.6.26 from
and tried to build it. It was successfully compiled with all modules. Commands to compile any kernel are as follows.

1) Go inside the kernel source code directory.
2) Create .config file by setting proper kernel configuration with
"make menuconfig"
3) "make bzImage" -- To build the kernel.
4) "make modules" -- To build depended module drivers (.ko file in 2.6 kernel)
5) "make modules_install" -- To install module drivers(.ko files) in
/lib/modules/ directory
6) Now we need to copy bzImage and initrd to /boot location. Do as follows from
kernel source directory.
"cp arch/x86/boot/bzImage" /boot/vmlinuz-2.6.26

7) Create initrd as follows.
"mkinitrd "
e.g. "mkinitrd initrd-2.6.26.img 2.6.26" -- In fedora syntax.

8) Now copy it in boot location using the command
"cp initrd-2.6.26.img /boot/"

9) We need to modify the grub.conf file to boot into the new kernel.

10) So, we are ready to boot into new kernel. Just rebooted and i got stuck :-(
Got an unrecognizable error, didn't understand. Need to look into it...

My first post

2008-07-18T09:02:00.000-07:00

After a long time i have created my blog account, inspired by Kushal Das , popularly known as KD ;-)