/*
* uvm_lwp_fork: fork a thread
*
* - a new PCB structure is allocated for the child process,
* and filled in by MD layer
* - if specified, the child gets a new user stack described by
* stack and stacksize
* - NOTE: the kernel stack may be at a different location in the child
* process, and thus addresses of automatic variables may be invalid
* after cpu_lwp_fork returns in the child process. We do nothing here
* after cpu_lwp_fork returns.
*/