I want to know
what's the extension of exexutable kernel file if any extension is allocated after inserting the module inside the kernel.
I think their is no extension given to exeutable file created{NOT sure}, if this is the case , then why and how linux executes the kernel code?

what's an "executable kernel file"?? 2.6 kernel modules conventionally have .ko suffixes if that's what you mean. not sure how a files extension is supposed to change once it's loaded either...

This is the answer I got form some site : please verify it :/

Executables files are recognizable by their data, but they can be executable only if it's execution permission bit is set (do you know about permission bitmask???). If executable bit is set, and if the file is an executable recognized by the running kernel, the application starts.

An executable run with the permission of the caller: so if you run an application as user, the application have the permission of the user. If the user is "root", the application can do anything root can do!

Then, certain executable can be run only with root permissions, because it may edit some configuration file or anything else. So the application can do its job only if the application was started by the administrator (root).

If any application need superuser privileges, but should be run by any user, executable file have an extra permission bit: the SUID bit (Set User ID). When this bit is set, the permissions at run time doesn't depends on the application caller, but the file owner (do you about file owner/group?). So if application has SUID bit set and it's owned by root, when any user run the SUID executable, run application with root privileges.

that doesn't appear to be the answer to any question i would guess at from your original post... if that IS an answer, then another answer is that executable files have no extension. linux is a tad cleverer than windows and doesn't rely on a crude 3 letter code to say what a program is...