797bdcc549
scheme allowed for 1024 PTE pages, each containing 256 PTEs. This yielded 2GB of KVA. This is not enough to boot a kernel on a 16GB box and in general too low for a 64-bit machine. By adding a level of indirection we now have 1024 2nd-level directory pages, each capable of supporting 2GB of KVA. This brings the grand total to 2TB of KVA.