Doubt fork system call

Dave Hylands dhylands at
Thu Sep 8 00:20:05 EDT 2011

Hi Rohan,

On Wed, Sep 7, 2011 at 8:45 PM, rohan puri <rohan.puri15 at> wrote:
> Thanks Darshan. I went through that section of the book. I do agree that
> fork(), vfork() in turn calls the clone() sys call which internally calls
> do_fork() method.
> The doubt which I have is there is a sys_fork() method which gets called
> when fork() system call is invoked. But from userspace is there any way in
> which we can make execute this code path, because if we make use of fork()
> it will call clone() sys call and follow that code path. What I am trying to
> figure out is that is that code (sys_fork() ) is redundant now or is
> something still using it.

My guess is that the fork syscall is still there because it is part of
the kernel API. Yes the clone call made fork redundant. But since fork
was already part of the API, they left it in. This way programs which
might use alternative runtime libraries, or which perhaps do system
calls directly, will continue to work.

Dave Hylands
Shuswap, BC, Canada

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