Re: clone(2) should be clone(3)

[Mike Frysinger <vapier-aBrp7R+bbdUdnm+yROfE0A@public.gmane.org>]

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On Tuesday 16 April 2013 01:42:56 Michael Kerrisk (man-pages) wrote:
> On Sun, Apr 7, 2013 at 9:03 PM, Mike Frysinger wrote:
> > also, the quoted syscall signature isn't the whole story.  there's
> > actually more variants:
> > #ifdef __ARCH_WANT_SYS_CLONE
> > #ifdef CONFIG_CLONE_BACKWARDS
> > SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
> >          int __user *, parent_tidptr,
> >          int, tls_val,
> >          int __user *, child_tidptr)
> > #elif defined(CONFIG_CLONE_BACKWARDS2)
> > SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
> >          int __user *, parent_tidptr,
> >          int __user *, child_tidptr,
> >          int, tls_val)
> > #else
> > SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
> >          int __user *, parent_tidptr,
> >          int __user *, child_tidptr,
> >          int, tls_val)
> > ...
> 
> I've worked in some of the above detail; see the Git copy of the page.
> 
> > these arches don't define __ARCH_WANT_SYS_CLONE:
> >         blackfin ia64 m68k sparc
> 
> I'm not sure of the significance of the above; can you explain?

the three clone variants i posted above are bracketed by the define 
__ARCH_WANT_SYS_CLONE.  so if the arch doesn't define that, it means it has its 
own implementation of clone() in its arch/$ARCH/ tree, so the exact prototype 
has to be tracked down from there.
-mike

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