_lwp_create(2) - NetBSD Manual Pages

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_LWP_CREATE(2)            NetBSD System Calls Manual            _LWP_CREATE(2)


NAME

     _lwp_create -- create a new light-weight process


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <lwp.h>

     int
     _lwp_create(ucontext_t *context, unsigned long flags, lwpid_t *new_lwp);


DESCRIPTION

     _lwp_create() causes creation of a new light-weight process, or LWP, and
     adds it to the current process.  The context argument specifies the ini-
     tial execution context for the new LWP including signal mask, stack, and
     machine registers.  The signal stack of the newly created light-weight
     process is reset to disabled.  If this context specifies invalid register
     values (for example privilege escalation by setting machine dependent
     bits forbidden for user processes), or does not specify cpu register val-
     ues (uc_flags does not have the _UC_CPU bit set), the call will fail and
     errno will be set to EINVAL.

     The following flags affect the creation of the new LWP:

     LWP_DETACHED  The LWP is created detached.  The resources associated with
                   a detached LWP will be automatically reclaimed by the sys-
                   tem when the LWP exits.  Otherwise, a terminated LWP's
                   resources will not be reclaimed until its status is
                   reported to another LWP via _lwp_wait(2).

     LWP_SUSPENDED
                   The LWP is created suspended, and will not begin execution
                   until it is resumed by another LWP via _lwp_continue(2).

     The LWP ID of the new LWP is stored in the location pointed to by
     new_lwp.


RETURN VALUES

     The _lwp_create() function returns the value 0 if successful; otherwise
     the value -1 is returned and the global variable errno is set to indicate
     the error.


ERRORS

     _lwp_create() will fail and no LWP will be created if:

     [EAGAIN]           The system-imposed limit on the total number of LWPs
                        under execution would be exceeded.  This limit is con-
                        figuration-dependent.

     [EFAULT]           The address pointed to by context or new_lwp is out-
                        side the process's allocated address space.

     [EINVAL]           The ucontext_t passed is invalid.

     [ENOMEM]           There is insufficient swap space for the new LWP.


SEE ALSO

     _lwp_continue(2), _lwp_exit(2), _lwp_wait(2), _lwp_makecontext(3)


HISTORY

     The _lwp_create() system call first appeared in NetBSD 2.0.

NetBSD 10.1                     April 21, 2017                     NetBSD 10.1