Re: [RFC c/r 2/4] [RFC] syscalls, x86: Add __NR_kcmp syscall v7

[Andi Kleen <andi@firstfloor.org>]

On Fri, Jan 27, 2012 at 10:24:03PM +0400, Cyrill Gorcunov wrote:
> Sure, I'll try to (btw, where I should send it to? And in which
> format novadays mans are written? In plain old troff or some
> human readable asciidocs?) And... should I post man page
> on LKML as well?

Manpages are written in troff with -man and you would add the ASCII output
of the manpage to the commit log and send the troff source at some
point to linux-man.

> 
> > 
> > As I understand it every time the kernel adds some new kind of state
> > this would need to be extended too? This would seem like a lot of work,
> > especially since you always need to synchronize kernel/user space.
> > How would the user space break if it doesn't know about some newly
> > added state?
> 
> Wait, maybe I should use kernel-doc here and put comments with example
> right on top of SYSCALL definition?

The basic problem is if this interface is at the right level of abstraction.
I have some doubts on that. It seems like a long term maintenance nightmare to 
me.  It may be better to put the loop that would call this into the kernel.

> > > +#ifdef CONFIG_SYSVIPC
> > > +		ret = kcmp_ptr((long)task1->sysvsem.undo_list,
> > > +			       (long)task2->sysvsem.undo_list,
> > > +			       KCMP_SYSVSEM);
> > 
> > I assume that's normally NULL.
> > 
> 
> Hmm.. Andi, I seem not following. And?

It just doesn't seem like a very useful thing to compare.

-Andi