(no subject)

[siva prasad]

Sorry for the newbie question..

Is it true that the ipc calls like
msgget(),shmget()...
are  not really system calls?

Cos in the file "asm/unistd.h" where the
system calls are listed as __NR_xxx we dont find
the appropriate listing for the ipc calls.
What I guessed was that all the ipc calls are
clubbed under the 'int ipc()' system call and this
is well listed in the "asm/unistd.h" 

Could some one explain why the ipc is implemented 
this way rather that implementing them as individual 
system calls as in UNIX.

Or is it the same way in UNIX




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Re: your mail

[Erik Mouw]

On Wed, May 16, 2001 at 08:05:38AM -0700, siva prasad wrote:
> Is it true that the ipc calls like
> msgget(),shmget()...
> are  not really system calls?

No, they all use a system call, but the system call is the same for all
functions.

> Cos in the file "asm/unistd.h" where the
> system calls are listed as __NR_xxx we dont find
> the appropriate listing for the ipc calls.
> What I guessed was that all the ipc calls are
> clubbed under the 'int ipc()' system call and this
> is well listed in the "asm/unistd.h" 

Right, they all use __NR_ipc. See sys_ipc() in
arch/i386/kernel.sys_i386.c, especially the comment right above the
function...

> Could some one explain why the ipc is implemented 
> this way rather that implementing them as individual 
> system calls as in UNIX.

Probably because the original designer liked it this way and nobody
cared enough to do it otherwise.

> Or is it the same way in UNIX

I don't know, I don't have Unix source available.


Erik

-- 
J.A.K. (Erik) Mouw, Information and Communication Theory Group, Department
of Electrical Engineering, Faculty of Information Technology and Systems,
Delft University of Technology, PO BOX 5031,  2600 GA Delft, The Netherlands
Phone: +31-15-2783635  Fax: +31-15-2781843  Email: J.A.K.Mouw@its.tudelft.nl
WWW: http://www-ict.its.tudelft.nl/~erik/