implement shared memory

Applications Programming
1

hi all
I have been asked to implement shared memory in user mode?But :rolleyes: im not understanding how to do this.And what does it mean in user mode?Is it that we need to simulate what kernal does...like attaching ,detaching memory..etc...?
And would also like to know why shared memory is called fastest IPC ?

2

Sounds like they've asked you to program something you don't have a clue about.

Here's a very good explanation with examples:

http://www.advancedlinuxprogramming.com/alp-folder/alp-ch05-ipc.pdf

3

Hi all,
Thank you for ur reply.
The link was good.But i am not understanding,somewhere it is mentioned that theres no kernal entry and system calls.But i see there are system calls for shared memory.....i.e.,shmget,shmat,shmctl.Are they not system calls?Dont they have any kernal entry?

4

Do you want shared memory without any system calls? Cannot be done.

You can use pipes, names pipes, or files to do that. But opening a file requires kernel access as well. So does printing to the screen. So what you're asking doesn't make any sense to me at the moment. Basically, you can think of any compiled C program as an interface to system and kernel calls.

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