Setup paging function signatures... Ready to be implemented.

Makefile

@@ -5,7 +5,7 @@ CC = ${HOME}/opt/cross/bin/i686-elf-gcc
 CPP = ${HOME}/opt/cross/bin/i686-elf-g++ 
 CFLAGS =  -ffreestanding -O2 -Wall -Wextra
 
-OFILES =$(BUILD_DIR)/boot.o $(BUILD_DIR)/kterm.o $(BUILD_DIR)/kernel.o $(BUILD_DIR)/memory.o	$(BUILD_DIR)/pit.o 	$(BUILD_DIR)/time.o	$(BUILD_DIR)/keyboard.o	 $(BUILD_DIR)/io.o 	$(BUILD_DIR)/gdtc.o $(BUILD_DIR)/idt.o $(BUILD_DIR)/pic.o $(BUILD_DIR)/sv-terminal.o $(BUILD_DIR)/string.o  
+OFILES =$(BUILD_DIR)/boot.o $(BUILD_DIR)/kterm.o $(BUILD_DIR)/kernel.o $(BUILD_DIR)/memory.o  $(BUILD_DIR)/paging.o	$(BUILD_DIR)/pit.o 	$(BUILD_DIR)/time.o	$(BUILD_DIR)/keyboard.o	 $(BUILD_DIR)/io.o 	$(BUILD_DIR)/gdtc.o $(BUILD_DIR)/idt.o $(BUILD_DIR)/pic.o $(BUILD_DIR)/sv-terminal.o $(BUILD_DIR)/string.o  
 
 SRC_DIR = src
 BUILD_DIR = build
@@ -96,3 +96,6 @@ $(BUILD_DIR)/sv-terminal.o:
 
 $(BUILD_DIR)/memory.o:
 	$(CPP) -c $(SRC_DIR)/kernel/memory/memory.cpp  -o $(BUILD_DIR)/memory.o $(CFLAGS) -fno-exceptions -fno-rtti
+
+$(BUILD_DIR)/paging.o:
+	$(CPP) -c $(SRC_DIR)/kernel/memory/paging.cpp -o $(BUILD_DIR)/paging.o $(CFLAGS) -fno-exceptions -fno-rtti

src/kernel/filesystems/FAT/FAT16.h

@@ -0,0 +1,8 @@
+#pragma once
+#include "../../vfs/File.h"
+
+
+class FAT16 : File  {
+public:
+    
+};

src/kernel/kernel.cpp

@@ -4,6 +4,9 @@ extern "C" void kernel_main (BootInfo* bootinfo) {
     init_serial();
     pit_initialise();
 
+    InitializePaging();
+    //Enable();
+
     startSuperVisorTerminal(bootinfo);
 }   
 

src/kernel/kernel.h

@@ -14,6 +14,7 @@ extern "C"
 
 #include "memory/memory.h"
 #include "memory/memoryinfo.h"
+#include "memory/paging.h"
 #include "bootcheck.h"
 
 #include "gdt/gdtc.h"

src/kernel/memory/PageDirectory.cpp

@@ -1,43 +0,0 @@
-#include "PageDirectory.h"
-
-void PageDirectory::enable()
-{
-
-
-    // https://wiki.osdev.org/Setting_Up_Paging
-    //set each entry to not present
-    // int i;
-    // for(i = 0; i < 1024; i++)
-    // {
-    //     // This sets the following flags to the pages:
-    //     //   Supervisor: Only kernel-mode can access them
-    //     //   Write Enabled: It can be both read from and written to
-    //     //   Not Present: The page table is not present
-    //     this->page_directory[i] = 0x00000002;
-    // }
-
-    // // holds the physical address where we want to start mapping these pages to.
-    // // in this case, we want to map these pages to the very beginning of memory.
-
-    // //we will fill all 1024 entries in the table, mapping 4 megabytes
-    // for(unsigned int i = 0; i < 1024; i++)
-    // {
-    //     // As the address is page aligned, it will always leave 12 bits zeroed.
-    //     // Those bits are used by the attributes ;)
-    //     first_page_table[i] = (i * 0x1000) | 3; // attributes: supervisor level, read/write, present.
-    // }
-
-    // // attributes: supervisor level, read/write, present
-    // this->page_directory[0] = ((unsigned int)first_page_table) | 3;
-
-    printf("Enable Paging!\n");
-
-    loadPageDirectory(this->page_directory);
-    enablePaging();
-}
-
-
-void PageDirectory::MapPhysicalToVirtualAddress ( address_t PAddress , address_t VAddress, uint32_t size  )
-{
-
-}

src/kernel/memory/PageDirectory.h

@@ -1,31 +0,0 @@
-#pragma once 
-#include <stdint.h>
-#include "./memory.h"
-#include "./../tty/kterm.h"
-#define KB 1024
-
-
-typedef uintptr_t address_t;
-
-static const int MAX_PAGES =  1024 * KB; // 4GB , 4kB/page
-static volatile address_t pmem_stack[MAX_PAGES];
-static volatile address_t pmem_stack_top = MAX_PAGES; // top down allocation
-
-extern "C" void loadPageDirectory (uint32_t* addr );
-extern "C" void enablePaging();
-
-struct page_directory_entry {};
-struct page_table_entry{};
-
-
-
-class PageDirectory {
-    public:
-    void enable ();
-    void MapPhysicalToVirtualAddress ( address_t PAddress , address_t VAddress, uint32_t size  );
-
-    private:
-    uint32_t page_directory[1024] __attribute__((aligned(4096))); // align on 4 kiloByte pages
-    uint32_t first_page_table[1024] __attribute__((aligned(4096))); // align on 4 kiloByte pages
-
-};

src/kernel/memory/paging.cpp

@@ -0,0 +1,49 @@
+#include "paging.h"
+PageDirectoryEntry kernel_directory[MAX_DIRECTORY_ENTRIES];
+
+void InitializePaging()
+{
+    // Identity map the first 8MB ... Physical addresses 0x00000000 to 0x007A1200
+
+
+    // Identity map the kernel space || our map to 3GB space
+
+
+    // Identity map VGA memory
+
+    
+}
+
+
+void AllocatePage(VIRTUAL_ADDRESS vaddr, PageDirectoryEntry& page_directory)
+{
+
+}
+
+
+void FreePage(VIRTUAL_ADDRESS vaddr , PageDirectoryEntry& page_directory)
+{
+
+}
+
+
+void Map ( PHYSICAL_ADDRESS paddr, VIRTUAL_ADDRESS vaddr, PageDirectoryEntry& page_directory)
+{
+
+}
+
+void Unmap(VIRTUAL_ADDRESS, PageDirectoryEntry& page_directory)
+{
+    // NOTE: I will implement lazy unmapping for now 
+    
+}
+
+
+void Enable()
+{
+    printf("Load into CR3 address: 0x%x\n", (uint32_t)(&kernel_directory[0]));
+    loadPageDirectory(&kernel_directory[0]);
+    enablePaging();
+
+    printf("Paging enabled!\n");
+}

src/kernel/memory/paging.definitions.h

@@ -0,0 +1,55 @@
+#pragma once
+#include <stdint.h>
+/*
+    This file contains some handy definitions for different types 
+    that have to do with paging in atleast 32 bit and maybe sometime in the future
+    also 64 bit mode.
+*/
+
+
+
+#define MAX_DIRECTORY_ENTRIES 1024
+#define MAX_PAGE_TABLE_ENTRIES 1024
+#define MAX_PAGES 1024
+
+#define PHYSICAL_ADDRESS uint32_t 
+#define VIRTUAL_ADDRESS uint32_t
+
+#define PageDirectoryEntry uint32_t
+#define PageTableEntry uint32_t
+
+
+
+
+// NOTE: FIXME: I am fairly certain these masks are off by one!
+
+#define PD32_PRESENT_MASK                   (0x1 << 0)
+#define PD32_READ_WRITE_MASK                (0x1 << 1)
+#define PD32_SUPERVISOR_MASK                (0x1 << 2)
+#define PD32_WRITE_THROUGH_MASK             (0x1 << 3)
+#define PD32_CACHE_DISABLE_MASK             (0x1 << 4)
+#define PD32_ACCESSED_MASK                  (0x1 << 5)
+#define PD32_AVAILABLE_1_4KB_MASK           (0x1 << 6)
+#define PD32_DISABLE_4MB_MASK               (0x1 << 6)
+#define PD32_PAGE_SIZE_MASK                 (0x1 << 7)
+#define PD32_GLOBAL_4MB_MASK                (0x1 << 8)
+#define PD32_AVAILABLE_2_4MB_MASK           ( 14 << 9)
+#define PD32_AVAILABLE_2_4KB_MASK           ( 15 << 8)
+#define PD32_ADDRESS_4KB_MASK               (0x8FFFF << 12)
+#define PD32_PAGE_ATTRIBUTE_TABLE_4MB_MASK  (0x1 << 12)
+#define PD32_HIGH_HALF_ADDRESS_4MB_MASK     (0x7F<< 13)
+#define PD32_RESERVED_4MB_MASK              (0x1 << 21)
+#define PD32_LOWER_HALF_ADDRESS_4MB_MASK    (0x1FF << 22)
+
+#define PT32_PRESENT_MASK                   (0x1 << 0)
+#define PT32_READ_WRITE_MASK                (0x1 << 1)
+#define PT32_SUPERVISOR_MASK                (0x1 << 2)
+#define PT32_WRITE_THROUGH_MASK             (0x1 << 3)
+#define PT32_CACHE_DISABLE_MASK             (0x1 << 4)
+#define PT32_ACCESSED_MASK                  (0x1 << 5)
+#define PT32_DIRTY_MASK                     (0x1 << 6)
+#define PT32_PAGE_ATTRIBUTE_TABLE_MASK      (0x1 << 7)
+#define PT32_GLOBAL_MASK                    (0x1 << 8)
+#define PT32_AVAILABLE_MASK                 (0x7 << 9)
+#define PT32_CACHE_DISABLE_MASK             (0x7FFFF << 12)
+

src/kernel/memory/paging.h

@@ -0,0 +1,21 @@
+#pragma once 
+#include "./memory.h"
+#include "./../tty/kterm.h"
+#include "paging.definitions.h"
+
+
+extern "C" void loadPageDirectory (uint32_t* addr );
+extern "C" void enablePaging();
+
+void InitializePaging();
+
+void Enable();
+
+void AllocatePage(VIRTUAL_ADDRESS, PageDirectoryEntry&);
+
+
+void FreePage(VIRTUAL_ADDRESS, PageDirectoryEntry&);
+
+
+void Map(PHYSICAL_ADDRESS, VIRTUAL_ADDRESS, PageDirectoryEntry&);
+void Unmap (VIRTUAL_ADDRESS, PageDirectoryEntry&);