PDIR_L1_NENTRIES
for (; j < PDIR_L1_NENTRIES; j++, k = 0, l = 0) {
j < PDIR_L1_NENTRIES && va < VM_MAX_KERNEL_ADDRESS;
#define PDIR_L1_PAGES ((PDIR_L1_NENTRIES * (1<<PDIR_L1_ENTRY_SHIFT)) / PAGE_SIZE)