Module pdpt 

x86-64 Page Directory Pointer Table (PDPT / L3)

This module wraps the third paging level (a.k.a. L3, PDPT):

• L3Index: index type for VA bits [38:30].
• PdptEntry: a single PDPT entry; may be a next-level pointer or a 1 GiB leaf.
• PdptEntryKind: decoded view of an entry (next PD or 1 GiB leaf).
• PageDirectoryPointerTable: a 4 KiB-aligned array of 512 entries.

Semantics

At the PDPT level, the PS bit controls whether the entry is a 1 GiB leaf (PS=1) or points to a Page Directory (PS=0). Leaf entries map 1 GiB and require 1 GiB physical alignment of the base address. Non-leaf entries hold the physical base of the next-level Page Directory (4 KiB aligned).

Invariants & Safety Notes

• PageDirectoryPointerTable is 4 KiB-aligned and contains exactly 512 entries.
• PdptEntry::present_next_with enforces PS=0; PdptEntry::present_leaf_with enforces PS=1.
• Callers must handle TLB maintenance after changing active mappings.
• Raw constructors perform no validation; use with care.

Structs

L3Index

Index into the PDPT (derived from virtual-address bits [38:30]).

PageDirectoryPointerTable

The PDPT (L3) table: 512 entries, 4 KiB aligned.

Pdpte

L3 PDPTE — pointer to a Page Directory (non-leaf; PS = 0).

Pdpte1G

L3 PDPTE (1 GiB leaf) — maps a single 1 GiB page (PS = 1).

Enums

L3View

Borrowed view into an L3 PDPTE.

PdptEntryKind

Decoded PDPT entry kind.

Unions

PdptEntry

L3 PDPTE union — overlays non-leaf Pdpte and leaf Pdpte1G on the same 64-bit storage.