vm_page_size
((((vaddr_t)(x) + (vm_page_size - 1)) / vm_page_size) * \
vm_page_size)
((((vaddr_t)(x)) / vm_page_size) * vm_page_size)
long iov_max, vm_page_size; /* round_page wants vm_page_size variable */
vm_page_size = sysconf(_SC_PAGE_SIZE);
ATF_REQUIRE(iov_max > 1 && vm_page_size > 1);