Kernel/Include/Arch/DTB.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <Types.h>
+#include <VM/PMM.h>
 
 typedef struct FDTHeader {
     UInt32 magic;                // 0xd00dfeed
@@ -32,4 +33,4 @@ enum {
     kFDTHeaderMagic = 0xd00dfeed,
 };
 
-void DTBParse(Pointer dtb);
+void DTBParse(Pointer dtb, VMBootMemoryMap* bootMap);

Kernel/Include/Lib/Stubs.h

@@ -0,0 +1,4 @@
+#pragma once
+#include <Types.h>
+
+void* memset(void* destination, int value, Size count);

Kernel/Include/VM/PMM.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <Types.h>
+
+enum {
+    kVMPageSize = 4096,
+    kVMBlocksPerByte = 8,
+    kVMMaxReservedRegions = 128,
+};
+
+typedef struct {
+    UInt64 base;
+    Size size;
+} VMMemoryRegion;
+
+typedef struct {
+    VMMemoryRegion totalRAM;
+    VMMemoryRegion reserved[kVMMaxReservedRegions];
+    UInt32 reservedCount;
+} VMBootMemoryMap;

Kernel/Source/Arch/DTB.c

@@ -4,8 +4,9 @@
 #include <Lib/Bytes.h>
 #include <Lib/Align.h>
 #include <Lib/String.h>
+#include <VM/PMM.h>
 
-void DTBParse(Pointer dtb) {
+void DTBParse(Pointer dtb, VMBootMemoryMap* bootMap) {
     FDTHeader* header = (FDTHeader*)dtb;
     if (BytesSwap32(header->magic) != kFDTHeaderMagic) {
         OSPanic("Invalid DTB magic");
@@ -16,7 +17,11 @@ void DTBParse(Pointer dtb) {
 
     BytePointer structs = (BytePointer)dtb + offStruct;
     ASCII* strings = (ASCII*)dtb + offStrings;
+
     ASCII* currentNode = "";
+    UInt32 currentDepth = 0;
+    UInt32 reservedMemoryDepth = 0; 
+    bool inReservedMemory = false;
 
     while (true) {
         UInt32 token = BytesSwap32(*(UInt32*)structs);
@@ -24,35 +29,61 @@ void DTBParse(Pointer dtb) {
 
         switch (token) {
             case FDTTokenBeginNode: {
+                currentDepth++;
                 currentNode = (ASCII*)structs;
 
+                if (StringStartsWith(currentNode, "reserved-memory")) {
+                    inReservedMemory = true;
+                    reservedMemoryDepth = currentDepth;
+                }
+
                 UInt32 nameLength = StringGetLength(currentNode);
                 structs += (nameLength + 1);
                 structs = (BytePointer)AlignUp64((Address)structs, 4);
-
                 break;
             }
             case FDTTokenProperty: {
                 UInt32 propertyLength = BytesSwap32(*(UInt32*)structs);
                 UInt32 nameOffset = BytesSwap32(*(UInt32*)(structs + 4));
                 structs += 8;
-
                 ASCII* propertyName = strings + nameOffset;
-                if (StringCompare(propertyName, "reg") == 0 && StringStartsWith(currentNode, "memory")) {
-                    UInt32* cells = (UInt32*)structs;
 
-                    UInt64 base = Merge32To64(BytesSwap32(cells[0]), BytesSwap32(cells[1]));
-                    UInt64 size = Merge32To64(BytesSwap32(cells[2]), BytesSwap32(cells[3]));
+                if (StringCompare(propertyName, "reg") == 0) {
+                    if (StringStartsWith(currentNode, "memory")) {
+                        UInt32* cells = (UInt32*)structs;
+                        UInt64 base = Merge32To64(BytesSwap32(cells[1]), BytesSwap32(cells[0]));
+                        UInt64 size = Merge32To64(BytesSwap32(cells[3]), BytesSwap32(cells[2]));
+                        OSLog("Main Memory: base=0x%x, size=0x%x\n", base, size);
+                        bootMap->totalRAM.base = base;
+                        bootMap->totalRAM.size = size;
+                    }
+                    else if (inReservedMemory && currentDepth > reservedMemoryDepth) {
+                        UInt32* cells = (UInt32*)structs;
+                        UInt64 base = Merge32To64(BytesSwap32(cells[1]), BytesSwap32(cells[0]));
+                        UInt64 size = Merge32To64(BytesSwap32(cells[3]), BytesSwap32(cells[2]));
 
-                    OSLog("Memory: base=0x%x, size=0x%x\n", base, size);
+                        UInt32 index = bootMap->reservedCount;
+                        bootMap->reserved[index].base = base;
+                        bootMap->reserved[index].size = size;
+                        bootMap->reservedCount++;
+                    
+                        OSLog("Reserved Region (%s): base=0x%x, size=0x%x\n", currentNode, base, size);
+                    }
                 }
+
                 structs += propertyLength;
                 structs = (BytePointer)AlignUp64((Address)structs, 4);
-
                 break;
             }
 
-            case FDTTokenEndNode: break;
+            case FDTTokenEndNode: {
+                if (inReservedMemory && currentDepth == reservedMemoryDepth) {
+                    inReservedMemory = false;
+                }
+                currentDepth--;
+                break;
+            }
+            
             case FDTTokenNOP: continue;
             case FDTTokenEnd: return;
             default:

Kernel/Source/KernelMain.c

@@ -1,4 +1,5 @@
 #include "../Common/bootinfo.h"
+#include <VM/PMM.h>
 #include <Arch/DTB.h>
 #include <OS/Log.h>
 #include <OS/Panic.h>
@@ -9,5 +10,8 @@ void KernelMain(Bootinfo* bootinfo) {
         OSPanic("Invalid bootinfo magic");
     }
 
-    DTBParse(bootinfo->dtb);
+    VMBootMemoryMap bootMap = {0};
+    bootMap.reservedCount = 0;
+    DTBParse(bootinfo->dtb, &bootMap);
+    OSLog("Meow...\n");
 }

Kernel/Source/Lib/Stubs.c

@@ -0,0 +1,6 @@
+#include <Lib/Stubs.h>
+#include <Lib/String.h>
+
+void* memset(void* destination, int value, Size count) {
+    return StringSet(destination, value, count);
+}

Kernel/Source/VM/PMM.c

@@ -0,0 +1,22 @@
+#include <VM/PMM.h>
+
+static inline Size BitmapGetByteIndex(Address address) {
+    return (address / kVMPageSize) / kVMBlocksPerByte;
+}
+
+static inline UInt8 BitmapGetBitOffset(Address address) {
+    return (UInt8)((address / kVMPageSize) % kVMBlocksPerByte);
+}
+
+static inline Boolean BitmapTest(const MemoryPointer bitmap, Address address) {
+    return (bitmap[BitmapGetByteIndex(address)] & (1U << BitmapGetBitOffset(address))) != 0;
+}
+
+static inline void BitmapSet(MemoryPointer bitmap, Address address) {
+    bitmap[BitmapGetByteIndex(address)] |= (1U << BitmapGetBitOffset(address));
+}
+
+static inline void BitmapUnset(MemoryPointer bitmap, Address address) {
+    bitmap[BitmapGetByteIndex(address)] &= ~(1U << BitmapGetBitOffset(address));
+}
+

Kernel/linker.ld

@@ -7,14 +7,22 @@ PHDRS
 SECTIONS
 {
     . = 0x40100000;
+    _kernelStart = .;
 
     .text : {
         *(.text.boot)
         *(.text*)
     } :text
 
+    . = ALIGN(8);
     .rodata : { *(.rodata*) } :text
     
+    . = ALIGN(4096);
     .data : { *(.data*) } :data
+    
+    . = ALIGN(8);
     .bss : { *(.bss*) *(COMMON) } :data
+
+    . = ALIGN(4096);
+    _kernelEnd = .;
 }