xid = -1:

    - on host? or at least !LOCK, then proceed
    - get a new context id (dynamic)
    - switch_user_struct (new id)
      if okay then
      - lower current caps
      - alloc s_info
        if successful
	- call set_initpid (flags)
	- current flags |= flags
	if not revert old id
	

xid = -2
    
    - set_initpid (flags)
      if okay then
      - lower current caps
      - if current flags & INIT
        current initpid = pid
      - current flags |= flags
      - return xid
    
xid = >0, <= MAX

    - search for context
      if not found create new one
    - switch_user_struct (new id)
      if okay then  
      - lower current caps 
      - current flags |= flags
    
    
    
set_initpid (flags)

    no s_info, return -EINVAL
    initpid already set, return -EPERM
    else current initpid = pid