gdt idt stuff

kernel/drivers/vga_stream_writer.c

@@ -57,6 +57,12 @@ void vga_initialize()
 
 void vga_putchar(char c) 
 {
+	if (c == '\n') {
+		terminal_row++;
+		terminal_column = 0;
+		return;
+	}
+
     const size_t index = terminal_row * VGA_WIDTH + terminal_column;
     terminal_buffer[index] = vga_entry(c, terminal_color);
 	if (++terminal_column == VGA_WIDTH) {

kernel/gdt.c

@@ -40,23 +40,44 @@
 #define GDT_DATA_PL3 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
                      SEG_LONG(0)     | SEG_SIZE(1) | SEG_GRAN(1) | \
                      SEG_PRIV(3)     | SEG_DATA_RDWR
- 
+
+typedef struct __attribute__((packed)) {
+    uint16_t limit;
+    uint32_t base;
+} gdt_ptr_t;
+                     
+uint64_t gdt[5];
+gdt_ptr_t gdtr;
+
+extern void load_gdt();
+
 uint64_t create_descriptor(uint32_t base, uint32_t limit, uint16_t flag)
 {
     uint64_t descriptor;
  
-    // Create the high 32 bit segment
+    descriptor  =  limit       & 0x000F0000;
-    descriptor  =  limit       & 0x000F0000;         // set limit bits 19:16
+    descriptor |= (flag <<  8) & 0x00F0FF00;
-    descriptor |= (flag <<  8) & 0x00F0FF00;         // set type, p, dpl, s, g, d/b, l and avl fields
+    descriptor |= (base >> 16) & 0x000000FF;
-    descriptor |= (base >> 16) & 0x000000FF;         // set base bits 23:16
+    descriptor |=  base        & 0xFF000000;
-    descriptor |=  base        & 0xFF000000;         // set base bits 31:24
  
-    // Shift by 32 to allow for low part of segment
     descriptor <<= 32;
  
-    // Create the low 32 bit segment
+    descriptor |= base  << 16;
-    descriptor |= base  << 16;                       // set base bits 15:0
+    descriptor |= limit  & 0x0000FFFF;
-    descriptor |= limit  & 0x0000FFFF;               // set limit bits 15:0
 
     return descriptor;
 }
+
+void init_gdt() {
+    gdt[0] = create_descriptor(0, 0, 0);
+    gdt[1] = create_descriptor(0, 0x000FFFFF, (GDT_CODE_PL0));
+    gdt[2] = create_descriptor(0, 0x000FFFFF, (GDT_DATA_PL0));
+    gdt[3] = create_descriptor(0, 0x000FFFFF, (GDT_CODE_PL3));
+    gdt[4] = create_descriptor(0, 0x000FFFFF, (GDT_DATA_PL3));
+
+    gdtr.limit = 5 * sizeof(uint64_t) - 1;
+    gdtr.base = (uint32_t)&gdt;
+
+    load_gdt();
+}
+ 

kernel/gdt_stubs.s

@@ -0,0 +1,14 @@
+.code32
+.extern gdtr 
+.global load_gdt
+load_gdt:
+    lgdt gdtr 
+    ljmpl $0x08, $reload_segments
+reload_segments:
+    mov $0x10, %ax
+    mov %ax, %ds 
+    mov %ax, %es
+    mov %ax, %fs 
+    mov %ax, %gs 
+    mov %ax, %ss 
+    ret 

kernel/idt.c

@@ -54,5 +54,4 @@ void init_idt() {
     }
 
     load_idt();
-    enable_int();
 }

kernel/idt.h

@@ -3,17 +3,17 @@
 
 #include <stdint.h>
 
-typedef struct {
+typedef struct __attribute__((packed)){
     uint16_t isr_low;   // The lower 16 bits of the ISR's address
     uint16_t kernel_cs; // The GDT segment selector the CPU will load into CS
     uint8_t  reserved;  // Set to 0
     uint8_t  attributes;// Type and attributes flags
     uint16_t isr_high;  // The higher 16 bits of the ISR's address
-} idt_entry __attribute__((packed));
+} idt_entry;
 
-typedef struct  {
+typedef struct __attribute__((packed)){
     uint16_t limit;
     uint32_t base;
-} idt_ptr __attribute__((packed));
+} idt_ptr;
 
 #endif

kernel/kmain.c

@@ -6,7 +6,7 @@
 #include <stdint.h>
 
 extern void init_idt();
-extern idt_entry create_idt_entry(uint32_t addr, uint16_t segment, uint8_t attributes);
+extern void init_gdt();
 
 void kernel_main(void) 
 {
@@ -15,7 +15,11 @@ void kernel_main(void)
   kout = &vga_print_stream;
   kout->trunc();
 
-  kprint("RockOS booting...");
+  kprint("RockOS booting...\n");
+
+  init_gdt();
+  kprint("GDT set\n");
 
   init_idt();
+  kprint("IDT set\n");
 }

makefile

@@ -6,6 +6,7 @@ OSNAME := rockos
 C_SOURCES := $(shell find kernel -type f -name '*.c')
 S_SOURCES := $(shell find kernel -type f -name '*.s')
 
+# This correctly generates paths like obj/kernel/main.o
 OBJECTS := $(patsubst %.c, obj/%.o, $(C_SOURCES)) $(patsubst %.s, obj/%.o, $(S_SOURCES))
 
 CFLAGS  := -ffreestanding -O2 -Wall -Wextra -Ikernel
@@ -13,6 +14,8 @@ LDFLAGS := -T kernel/linker.ld
 
 .PHONY: all run clean
 
+all: $(OSNAME).iso
+
 $(OSNAME).bin: $(OBJECTS)
 	$(LD) $(LDFLAGS) -o $@ $(OBJECTS)
 
@@ -22,11 +25,12 @@ $(OSNAME).iso: $(OSNAME).bin grub.cfg
 	cp grub.cfg isodir/boot/grub/grub.cfg
 	grub-mkrescue -o $(OSNAME).iso isodir
 
-obj/%.o: %.c
+# FIX: Pattern rules now explicitly expect the 'kernel' directory layout
+obj/kernel/%.o: kernel/%.c
 	@mkdir -p $(dir $@)
 	$(CC) -c $< -o $@ $(CFLAGS)
 
-obj/%.o: %.s
+obj/kernel/%.o: kernel/%.s
 	@mkdir -p $(dir $@)
 	$(CC) -c $< -o $@ $(CFLAGS)