netbsd man page for proc_trampoline

CPU_LWP_FORK(9) 					   BSD Kernel Developer's Manual					   CPU_LWP_FORK(9)

NAME
     cpu_lwp_fork, child_return, proc_trampoline -- finish a fork operation

SYNOPSIS
     #include <sys/proc.h>

     void
     cpu_lwp_fork(struct lwp *l1, struct lwp *l2, void *stack, size_t stacksize, void (*func)(void *), void *arg);

     void
     child_return(void *arg);

DESCRIPTION
     cpu_lwp_fork() is the machine-dependent portion of fork1() which finishes a fork operation, with child lwp l2 nearly set up.  It copies and
     updates the PCB and trap frame from the parent l1, making the child ready to run.

     cpu_lwp_fork() rigs the child's kernel stack so that it will start in proc_trampoline().  proc_trampoline() does not have a normal calling
     sequence and is entered by cpu_switch().  If an alternate user-level stack is requested (with non-zero values in both the stack and stacksize
     arguments), the user stack pointer is set up accordingly.

     After being entered by cpu_switch() and while running in user context (within the kernel) proc_trampoline() will invoke the function func
     with the argument arg.  If a kernel thread is being created, the return path and argument are specified with func and arg.  If a user process
     is being created, fork1() will pass child_return() and l2 to cpu_lwp_fork() as func and arg respectively.	This causes the newly-created
     child process to go directly to user level with an apparent return value of 0 from fork(2), while the parent process returns normally.

SEE ALSO
     fork(2), cpu_switchto(9), fork1(9)

BSD
								  April 13, 2010							       BSD