Re: [patch 7/8] fdmap v2 - implement sys_socket2

[Davide Libenzi <davidel@xmailserver.org>]

On Wed, 6 Jun 2007, Alan Cox wrote:

> > The sys_accept() system call has been modified to return a file
> > descriptor inside the non-sequential area, if the listening fd is.
> > The sys_socketcall() system call has been also changed to support
> > a new SYS_SOCKET2 indentifier.
> 
> This still all seems really really ugly. Is there anything wrong with
> throwing all these extra cases out and replacing the entire lot with
> 
> 	prctl(PR_SPARSEFD, 1);
> 
> to turn on sparse fd allocation for a process ?

There was a little discussion where I tried to whisper something similar, 
but Linus and Uli shot me :) - with good reasons IMO.
You may link to runtimes that are not non-sequentialfd aware, and will 
break them.



> Anyone needing to deal with certain special fds will use dup2() anyway so
> a task global switch seems to be cleaner and make the behaviour simply to
> flip on, with no extra calls (and you need to submit man pages for them
> all too), and also more importantly no new glibc stuff should be needed,
> and a process can try to set sparsefd, fail and carry on so its more
> portable and back portable.

Man pages! Damn, I forgot Michael Kerrisk is already waiting for the other 
stuff :(



- Davide


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