Hi!
> This gives a brief overview of the clone3() system call. We should
Thanks!
> eventually describe more details in existing clone(2) man page or in
> a new man page.
M. Kerrisk (see MAINTAINERS) maintains man pages...
> Changelog[v8]:
> - clone2() is already in use in IA64. Rename syscall to clone3()
...
> Index: linux-2.6/Documentation/clone2
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ linux-2.6/Documentation/clone2 2009-10-12 19:54:38.000000000 -0700
clone3?
> +struct clone_struct {
> + u64 flags;
> + u64 child_stack;
u64 seems wrong on 32 bit platforms. ulong?
> + u32 nr_pids;
So nr_pids is either 1 or 2?
> + u32 reserved1;
> + u64 parent_tid;
> + u64 child_tid;
> + u64 reserved2;
> +};
> +
> + See CLONE_NEWPID section of clone(2) man page for details about pid
> + namespaces.
> +
> + The order pids in @pids corresponds to the nesting order of pid-
> + namespaces, with @pids[0] corresponding to the init_pid_ns.
Ok, so I'm confused.
> + If a pid in the @pids list is 0, the kernel will assign the next
> + available pid in the pid namespace, for the process.
> +
> + If a pid in the @pids list is non-zero, the kernel tries to assign
> + the specified pid in that namespace. If that pid is already in use
> + by another process, the system call fails with -EBUSY.
...
> + On failure, clone3() returns -1 and sets 'errno' to one of following
> + values (the child process is not created).
Inconsistent with above. Syscalls really return -ERRCODE, errno is
glibc magic.
> +Example:
> +
> + pid_t pids[] = { 77, 99 };
> + struct clone_struct cs;
> +
> + cs.flags = (u64) SIGCHLD;
> + cs.child_stack = (u64) setup_child_stack();
> + cs.nr_pids = 2;
> + cs.parent_tid = 0LL;
> + cs.child_tid = 0LL;
> +
> + rc = syscall(__NR_clone3, &cs, pids);
Hmm, is there reason why pids are not at the end of struct
clone_struct? Passing most parameters in special structure, then pids
separately is strange...
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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