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


lwp_create, lwp_create2 -- spawn a new lwp


Standard C Library (libc, -lc)


#include <sys/lwp.h> int lwp_create(struct lwp_params *params); int lwp_create2(struct lwp_params *params, const cpumask_t *mask);


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.


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.


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


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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