headers/gdt.h

@@ -3,7 +3,8 @@
 #include "tss.h"
 #include <stdint.h>
 
-#define GDT_SIZE 8
+#define GDT_ADDRESS 0xC0105040
+#define GDT_SIZE    8
 
 // https://wiki.osdev.org/Global_Descriptor_Table#GDTR
 struct gdt_descriptor {

src/gdt/gdt.c

@@ -7,7 +7,7 @@ extern void set_gdt(uint32_t gdt_ptr);
 
 struct tss TSS;
 uint8_t gdt_entries[GDT_SIZE * 8];
-struct gdt_descriptor gdtr;
+struct gdt_descriptor *gdtr = (struct gdt_descriptor *)GDT_ADDRESS;
 
 static void set_gdt_entry_value(uint8_t *target, uint32_t base, uint32_t limit,
                                 uint8_t access, uint8_t granularity)
@@ -37,8 +37,8 @@ static void set_gdt_entry_value(uint8_t *target, uint32_t base, uint32_t limit,
 
 void init_gdt(void)
 {
-	gdtr.size = 8 * GDT_SIZE - 1;
-	gdtr.base = (uint32_t)&gdt_entries[0];
+	gdtr->size = 8 * GDT_SIZE - 1;
+	gdtr->base = (uint32_t)&gdt_entries[0];
 
 	set_gdt_entry_value(gdt_entries + 0x00, 0, 0, 0, 0); // Null segment
 
@@ -95,5 +95,5 @@ void init_gdt(void)
 	set_gdt_entry_value(gdt_entries + GDT_OFFSET_TSS, (uint32_t)&TSS,
 	                    sizeof(struct tss) - 1, 0x89, 0);
 
-	set_gdt(((uint32_t)&gdtr));
+	set_gdt(((uint32_t)gdtr));
 }

src/interrupt/irq.s

@@ -38,7 +38,10 @@ irq_common_stub:
     iret
 
 irq0:
+	push eax
+	mov eax, [esp + 4]
 	mov [esp_backup], esp
+	pop eax
 	push 0
 	push 32
 	jmp irq_common_stub

src/kernel.c

@@ -61,7 +61,7 @@ void kernel_main(multiboot_info_t *mbd, uint32_t magic)
 	 */
 	/*         "Martin 03:50, 22 March 2009 (UTC)\n"); */
 	create_kernel_task();
-	exec_fn(owo);
+	exec_fn(awa);
 	// exec_fn(owo);
 	shell_init();
 }

src/multitasking/switch_to_task.s

@@ -11,7 +11,7 @@ switch_to_task:
 
 	// save the current stack pointer to the old stack
 	mov [current_task+0], esp
-
+	
 	mov edi, [esp_backup] // get eip
 	mov [current_task+16], edi	// save instruction before Interrupt
 
@@ -31,14 +31,13 @@ switch_to_task:
 	je .END 
 //	mov cr3, ebx
 
-
-.END:
+	// TODO replace the eip store in stack by the [current_task+16](current_task->eip)  
 	mov edi, [current_task+16]
 	mov [esp_backup], edi
-	
+.END:
 	pop esi
 	pop edi
 	pop ebp
 	pop ebx
 
-	ret 
+	ret // this will also change eip to the next task's instructions