paging at boot works now!!!!

linker.ld

@@ -1,29 +1,24 @@
 ENTRY(_start)
 
-SECTIONS {
-	. = ALIGN(8);
-    .boot : {
-        KEEP(*(.multiboot))
-    }
-	. = 1M; /* Load kernel at 1MB */
+KERNEL_VIRT_BASE = 0xC0000000;
+KERNEL_PHYS_BASE = 0x00100000;
 
-	.text BLOCK(4K) : ALIGN(4K)
-	{
+SECTIONS {
+    . = KERNEL_VIRT_BASE;
+
+    .text : AT(KERNEL_PHYS_BASE) {
         *(.text)
     }
 
-	.rodata BLOCK(4K) : ALIGN(4K)
-	{
+    .rodata : AT(KERNEL_PHYS_BASE + (ADDR(.rodata) - KERNEL_VIRT_BASE)) {
         *(.rodata)
     }
 
-	.data BLOCK(4K) : ALIGN(4K)
-	{
+    .data : AT(KERNEL_PHYS_BASE + (ADDR(.data) - KERNEL_VIRT_BASE)) {
         *(.data)
     }
 
-	.bss BLOCK(4K) : ALIGN(4K)
-	{
+    .bss : AT(KERNEL_PHYS_BASE + (ADDR(.bss) - KERNEL_VIRT_BASE)) {
         *(COMMON)
         *(.bss)
     }

src/bootload/GDT.asm

@@ -22,7 +22,7 @@ gdt_end:
 
 gdt_descriptor:
     dw gdt_end - gdt_start - 1
-    dd gdt_start
+    dd gdt_start - 0xC0000000 + 0x00100000 ; paging, thank me later.
 
 CODE_SEG equ gdt_code - gdt_start
 DATA_SEG equ gdt_data - gdt_start

src/bootload/boot.asm

@@ -1,8 +1,17 @@
+; TODO:
+; load GDT 		[x]
+; enter long m. [x]
+; enable paging [x] 
+; fix damn grub parameter passing [x]
+
 ; constants for multiboot
 MAGIC equ 0xE85250D6
 ARCH equ 0 ; 0 for i386, 4 for MIPS
 HDRLEN equ 24 ; Total length: 4 fields + end tag
 CHECKSUM equ -(MAGIC + ARCH + HDRLEN)
+KERNEL_VIRT_BASE equ 0xC0000000
+KERNEL_PHYS_BASE equ 0x00100000
+KERNEL_OFFSET equ (-KERNEL_VIRT_BASE)+KERNEL_PHYS_BASE
 
 section .multiboot_header
 align 8
@@ -25,6 +34,16 @@ stack_bottom:
 resb 16384 ; 16 KiB is reserved for stack
 stack_top:
 
+align 4096
+PAG_mainPD:
+    resd 1024
+align 4096
+PAG_identityPT:
+    resd 1024
+align 4096
+PAG_kernelPT:
+    resd 1024
+
 section .rodata
 %include "src/bootload/GDT.asm"
 
@@ -32,24 +51,12 @@ section .text ; entrypoint for bootloader
 [BITS 32]
 global _start:function (_start.end - _start)
 _start:
-	; To set up a stack, we set the esp register to point to the top of our
-	; stack (as it grows downwards on x86 systems). This is necessarily done
-	; in assembly as languages such as C cannot function without a stack.
-	mov esp, stack_top
-	mov ebp, esp
-	
-	mov ecx, eax ; move multiboot magic number to ecx
-
-	; TODO:
-	; load GDT 		[x]
-	; enter long m. [ ]
-	; init FPU		[ ]
-
-	; load GDT
 	cli
-	lgdt [gdt_descriptor]
-	jmp   CODE_SEG:.final ; if I get problems, check this line here, future me!
+	lgdt [gdt_descriptor + KERNEL_OFFSET]
+	jmp   CODE_SEG:.final + KERNEL_OFFSET ; if I get problems, check this line here, future me!
 .final:
+	mov edx, eax ; we need the boot shit from grub still
+	; so now eax -> edx and ebx -> ebx
 	mov   AX, DATA_SEG ; data segment selectors
 	mov   DS, AX
 	mov   ES, AX
@@ -57,8 +64,53 @@ _start:
 	mov   GS, AX
 	mov   SS, AX
 
-	push ecx ; magic number
-	push ebx ; info structure
+	mov ecx, 1024 ; 1024 * 4KB = 4MB
+	mov edi, PAG_identityPT + KERNEL_OFFSET
+	mov eax, 0
+
+	.fill_identity:
+		mov [edi], eax
+		or dword [edi], 0x3
+		add eax, 0x1000
+		add edi, 4
+		loop .fill_identity
+
+	mov ecx, 1024
+	mov edi, PAG_kernelPT + KERNEL_OFFSET
+	mov eax, KERNEL_PHYS_BASE
+
+	.fill_kernel:
+		mov [edi], eax
+		or dword [edi], 0x3
+		add eax, 0x1000
+		add edi, 4
+		loop .fill_kernel
+
+	; identity PT = entry 0
+	mov eax, PAG_identityPT + KERNEL_OFFSET
+	or eax, 0x3
+	mov [PAG_mainPD + KERNEL_OFFSET + 0*4], eax
+
+	; kernel PT = entry 768
+	mov eax, PAG_kernelPT + KERNEL_OFFSET
+	or eax, 0x3
+	mov [PAG_mainPD + KERNEL_OFFSET + 768*4], eax
+	
+	mov eax, PAG_mainPD + KERNEL_OFFSET
+	mov cr3, eax
+	mov eax, cr0
+	or eax, 0x80000000
+	mov cr0, eax
+
+	jmp .pagingfinished
+.pagingfinished
+	; fix stack once again and since we need to keep the contents, we just add an offset
+	mov esp, stack_top
+	mov ebp, stack_bottom
+
+	push edx
+	push ebx
+
 	extern kernel_main
 	call kernel_main
 	add esp, 8 ; remove arguments

src/headers/paging.h

@@ -0,0 +1,9 @@
+#include "stddef.h"
+#include "stdlib.h"
+
+typedef uint32_t PAG_PT_entry_t;
+typedef PAG_PT_entry_t PAG_PT_t[1024];
+typedef PAG_PT_t PAG_PD_t[1024];
+
+extern PAG_PD_t PAG_mainPD;
+

src/kernel/entry.c

@@ -32,15 +32,9 @@ void kernel_main(struct multiboot_info* header, uint32_t magic) {
 
 	kputstr("Hello JPOS, World!\n");
 
-	if (magic != MULTIBOOT2_BOOTLOADER_MAGIC) {
-		kputstr("Invalid magic from bootloader.\n");
-		return;
-	}
-
-	kputstr("Got past magic check.\n");
-
 	kputstr("Entering Graphics mode: ");
 	VGA_switch(VGA_values);
+	*(uint8_t*)0xA0000 = 1;
 	kputstr("OK\n");
 	
 	VGA_clear((VGA_pixel){0xFF,0xFF,0xFF});
@@ -56,6 +50,13 @@ void kernel_main(struct multiboot_info* header, uint32_t magic) {
 	}
 	kputstr("OK\n");
 
+	if (magic != MULTIBOOT2_BOOTLOADER_MAGIC) {
+		kputstr("Invalid magic from bootloader.\n");
+		return;
+	}
+
+	kputstr("Got past magic check.\n");
+
 	kputstr("Setting up IRQs: ");
 	for (uint8_t i=0;i<16;i++) {
 		idt_set_descriptor(i+0x20, irq_stub_table[i], 0x8E);
@@ -86,7 +87,5 @@ void kernel_main(struct multiboot_info* header, uint32_t magic) {
 
 	IRQ_registerhandler(0x00, &tick);
 
-	
-
 	while (1) {}
 }