>
> > +struct clone_struct {
> > + u64 flags;
> > + u64 child_stack;
>
> u64 seems wrong on 32 bit platforms. ulong?
That would make it incompatible between 64 bit kernels and
32 bit user space, requiring a wrapper. Better leave it at u64.
> > + 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.
Quite the opposite is true.
The man page describes what the user space sees, which is errno. Returning
-ERRCODE to libc from the kernel is part of the architecture specific
kernel ABI and should not be documented in this place but in the architecture
documentation.
> > + 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...
I suggested doing that, it's a lot easier to handle fixed length data
structures than an array at the end.
Arnd <><
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