int l4_unmap(void *virtual, unsigned long npages, l4id_t tid); 

• Removes virtual to physical address mappings from a thread's address space.

• Removes a virtual address mapping from the address space of a task identified by tid, starting from the virtual address virtual, spanning npages number of pages.

/* 
 * Unmaps the given virtual address from current address space
 * spanning npages number of pages. Returns negative value
 * if the address was already unmapped.
 */
static inline void *l4_unmap_helper(void *virt, int npages)