My Tech notes

Bottom half and techniques to implement

Bottom half" is a generic operating system term referring to the deferred portion of interrupt processing, so named because it represents the second, or bottom, half of the interrupt processing solution. In Linux, the term currently has this meaning, too. All the kernel's mechanisms for deferring work are "bottom halves." Some people also confusingly call all bottom halves "softirqs," but they are just being annoying. "Bottom half" also refers to the original deferred work mechanism in Linux. This mechanism is also known as a "BH," so we call it by that name now and leave the former as a generic description. The BH mechanism was deprecated a while back and fully removed in 2.5. Currently, there are three methods for deferring work: softirqs, tasklets, and work queues. Tasklets are built on softirqs and work queues are entirely different.

Using Softirqs
Softirqs are reserved for the most timing-critic…

You can use "cvs add" command to check-in any big source like linux kernel instead of "cvs import" since the "cvs import" command is creating branches with versions 1.1.1.1 instead of 1.1.

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Suppose you want to check-in a large source which is inside a folder name “newfolder”.

To add the folder “newfolder” and it sub-directories into CVS first do

$ find newfolder –type d –print | xargs cvs add

Then to add the files inside the “newfolder” and its subdirectories

$ find newfolder –name CVS –prune –o –type f –print | xargs cvs add

Then we have to commit these into CVS. The “cvs commit” is recursive, so we can give the following command

$ cvs commit –m “comment” newfolder/.

NOTE Please verify if everything has been checked in with these steps by checking out and compiling. I found some files (only which are last) didn’t get added while doing so for kernel. This…

I would like to share a childhood story which my father ceremoniously told us children every year. The story is about Tom’s mother.

Tom has a friend, John. One day, John was being chased by the police and he knocks on Tom’s door. “Please hide me”, he pleads, when Tom’s mother opens the door. Tom’s mother lets him in and gives him refuge. When the police, following close on John’s heels, arrive, Tom’s mother peeps out of the window and asks, “Sergeant, what’s the matter?” The policeman asks: “Did you see John? He came this way”. “No sergeant, I haven’t seen John”, she says.

After the police have left, Tom’s mother goes to the backyard, and helps John to escape. She does so, even after the police inform her that John had a massive fight with Tom, in which Tom was killed. John was her son’s killer.

I found the story boring and meaningless in those days. Now it strikes me as inspirational and revealing. Look around, TV serials, movies, fictional thrillers are built around the theme of veng…

Was chatting with people from other country a problem because you don’t understand their language? Google has the solution, GTalk translates your chat in 24 different languages on he fly with the help of translation bots. It can’t get any better can it?

Here is how you do it…. if you want to translate English to Chinese, add "en2zh@bot.talk.google.com" to your GTalk account, where "en2zh" is [from language - en - English]2[to language - zh - Chinese]@bot.talk.google.com, similarly you can translate using 24 different bots. These bots are named using two-letter language abbreviations, click here to see the list of abbreviations and know what each abbreviation means.Following are the available bot addresses:
ar2en de2en de2fr el2en en2ar en2de en2el en2es en2fr en2it en2ja en2ko en2nl en2ru en2zh es2en fr2de fr2en it2en ja2en ko2en nl2en ru2en zh2enStart adding the bots of your choice and showoff your multilingual skills…cool stuff Thanks

It is not completely understood how these two systems are interconnected, if at all. However, the organization in the octopus demonstrates a sophistication that was not described yet in other animals. In the octopus, the short-term and long-term systems are working in parallel, but not independently. This is so because the long-term memory area -- in addition to its capacity to store long-term memories -- also regulates the rate at which the short-term memory system acquires short-term memories. This regulatory mechanism is probably useful in cases where faster learning is significant for the octopus' survival in emergency or risky situations. clipped from www.sciencedaily.com Research on octopuses has shed new light on how our brains store and recall memory, Why octopuses? Octopuses and other related creatures, known as cephalopods, are considered to be the most intelligent invertebrates because they have relatively large brains and they can be trained for various learning and memo…

set-user-id (suid) flag set on file
A binary owned by root with set-user-id flag set runs with root privileges, even when an ordinary user invokes it. [2] This is useful for executables (such as pppd and cdrecord) that need to access system hardware. Lacking the suid flag, these binaries could not be invoked by a non-root user.
-rwsr-xr-t 1 root 178236 Oct 2 2000 /usr/sbin/pppd

Using chmod how to set this flag?
A numeric mode is from one to four octal digits (0-7), derived by adding up the bits with values 4, 2, and 1. Omitted digits are assumed to be leading zeros, except that if the first digit is omitted, a directory's set user and group ID bits are not affected. The first digit selects the set user ID (4) and set group ID (2) and restricted deletion or sticky (1) attributes.
The second digit selects permissions for the user who owns the file: read (4), write (2), and execute (1);
the third selects permissions for other users in the file&#…

The official date for the launch of Firefox 3 is June 17, 2008. Join our community and this effort by pledging today.



Google has updated their Firefox toolbar to make it compatible with Firefox 3 - the browser that is due tomorrow.

It is very much possible that we delete some useful files by “rm –rf” or rm, One can make use of “alias “command to prevent deleting useful files. Like $ alias rm="rm -iv"Whenever one uses rm it will ask for users permission Ex.$ “rm: remove regular file `test.c'? y”And also it will give information to user that xyz.c file is deleted, Ex. $ removed `test.c'One can add this line alias rm="rm -iv" in .bashrc file so that whenever user login this options will be set as default.

S P Tulsian - Looks attractive at current levels

Q - Bhagwan what should we do for an Erect Body
Posture, which in turn will help us to be in permanent
Break Thru state ?

Bhagwan: a) What you must do is, you must not get up late in
the morning. You should always get up before Sunrise. That is
very very important.

b) Most important part is, always the day must begun, with
gratitude to ones parents.

c) Third is, you should never eat till your full stomach. Always
some space should be left empty, while eating.

d) Then at night, before you sleep, you must always sit down for
a moment and see what all have happened during the day and
how was your mind functioning, what all feelings you had, how you
did you escape from your thoughts, its ugliness and then, try to
confront it for some time and then go to sleep. Then you will find
that you are intensly aware of your ugliness and there will be no
conflict at all. Then there will be dramatically change and you will
be progressing spiritually, as well.

If all these is maintained properly, it is more than enou…