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LWP_CREATE(2)            DragonFly System Calls Manual           LWP_CREATE(2)


NAME

     lwp_create, lwp_create2 -- spawn a new lwp


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <sys/lwp.h>

     int
     lwp_create(struct lwp_params *params);

     int
     lwp_create2(struct lwp_params *params, const cpumask_t *mask);


DESCRIPTION

     The lwp_create() and the lwp_create2() function spawn a new lwp in the
     current process.  In a way, lwp_create() and lwp_create2() are similar to
     fork(2).  However, lwp_create() and lwp_create2() do not return twice as
     parent and child.  Instead, the new lwp will execute a function provided
     by the params argument which is a pointer to a struct lwp_params.

     struct lwp_params {
             void (*func)(void *);   /* Function to start execution */
             void *arg;              /* Parameter to this function */
             void *stack;            /* Stack address to use */
             lwpid_t *tid1;          /* Address to copy out new tid */
             lwpid_t *tid2;          /* Same */
     };

     A function pointer func specifies the function to be executed in the new
     lwp.  It is the duty of func() to correctly terminate execution of the
     lwp, either by calling extexit(2) or exit(3).  If func() returns,
     behavior is unspecified.  The only argument passed to func() is arg.

     The new lwp starts with its stack frame set to stack.  Note that both
     func and stack are mandatory.  If either is invalid, behavior is
     unspecified.

     The fields tid1 and tid2 point to variables where the tid of the new lwp
     shall be stored.  Two parameters are provided so that storage for both
     parent and child can be specified separately.  Setting any of these to
     NULL causes the respective tid not to be copied out.

     The mask argument to lwp_create2() specifies the new lwp's CPU affinity
     mask.  NULL means no special CPU affinity settings.


RETURN VALUES

     Upon successful completion, the value 0 is returned; otherwise the
     value -1 is returned and the global variable errno is set to indicate the
     error.


SEE ALSO

     extexit(2), rfork(2), exit(3)


HISTORY

     The lwp_create() function first appeared in DragonFly 1.9.  The
     lwp_create2() function first appeared in DragonFly 4.7.

DragonFly 4.7                  January 14, 2017                  DragonFly 4.7

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