feat: refactor memory management and integrate memblock

- Updated physical memory management (PMM) to utilize memblock for memory layout and frame allocation.
- Enhanced the virtual memory manager (VMM) to allocate the frame map from memblock, ensuring it starts at the correct virtual address without relocation.
- Improved frame allocation and deallocation functions to handle physical addresses more consistently.
- Adjusted the slab allocator to correctly convert between physical and virtual addresses.
- Refined page fault handling to ensure proper frame allocation and address translation.
- Streamlined the initialization process for PMM and VMM, ensuring a more robust setup of memory structures.

Co-authored-by: Copilot <copilot@github.com>

1 files changed, 53 insertions, 0 deletions

diff --git a/na/include/lume/memblock.h b/na/include/lume/memblock.h
new file mode 100644
index 0000000..41baf34
--- /dev/null
+++ b/na/include/lume/memblock.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (C) 2026 Richard Qin */
+
+#pragma once
+
+/*
+ * memblock — Boot-time physical memory allocator
+ *
+ * A simple region-based allocator active from early boot until
+ * the buddy system (PMM) takes over.  Inspired by Linux's memblock.
+ *
+ * Lifetime:
+ *   1. memblock_init()       — discovers RAM via FDT, reserves kernel image
+ *   2. vmm_init()            — uses memblock_alloc for page table pages & frame_map
+ *   3. pmm_init()            — absorbs remaining free regions into buddy
+ *   4. memblock_retire()     — marks memblock inactive; all alloc via PMM
+ *
+ * This eliminates the need for post-init pointer relocation when
+ * rebinding frame_map to a VMEMMAP virtual address.
+ */
+
+#include <lume/types.h>
+
+inline constexpr int kMemblockMaxRegions = 128;
+
+/* Initialize memblock: scan FDT for RAM, reserve kernel image + firmware. */
+void memblock_init(uint64 fdt_paddr);
+
+/* Mark a physical range as reserved (will not be handed to buddy). */
+void memblock_reserve(uint64 base, uint64 size);
+
+/* Allocate `size` bytes aligned to `align` from top of free memory.
+ * Returns PA, or 0 on failure.  Used for frame_map. */
+uint64 memblock_alloc_top(uint64 size, uint64 align);
+
+/* Allocate `size` bytes aligned to `align` from bottom of free memory.
+ * Returns PA, or 0 on failure.  Used for page table pages. */
+uint64 memblock_alloc(uint64 size, uint64 align);
+
+/* Query memory layout (same info as FDT). */
+uint64 memblock_get_mem_base();
+uint64 memblock_get_mem_size();
+
+/* Is memblock still the active allocator? */
+bool memblock_is_active();
+
+/* Mark memblock as retired (PMM takes over). */
+void memblock_retire();
+
+/* Iterate all free (unreserved) regions in ascending order.
+ * Used by pmm_init() to feed free pages into the buddy system. */
+void memblock_for_each_free(void (*cb)(uint64 base, uint64 size, void* ctx),
+                            void* ctx);