From 086bac07ed7577afbb28e7636e64a6ee747d80b1 Mon Sep 17 00:00:00 2001
From: Ruslan Isaev <ubijca16@gmail.com>
Date: Tue, 18 Mar 2025 15:45:51 +0300
Subject: [PATCH] gdt: make gdt setup run before kmain

---
 src/boot.asm | 16 ++++++++++++++++
 src/gdt.asm  | 30 ++++++++++++++++++++++++++++++
 src/kernel.c |  2 +-
 3 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 src/gdt.asm

diff --git a/src/boot.asm b/src/boot.asm
index a16f266..6ae6fa3 100644
--- a/src/boot.asm
+++ b/src/boot.asm
@@ -6,11 +6,27 @@ section         .text
         dd      0x00
         dd      - (0x1BADB002+0x00)
 
+section .gdt
+%include "src/gdt.asm"
+
+section .text
 global start
 extern kmain            ; this function is gonna be located in our c code(kernel.c)
 
 start:
         cli             ;clears the interrupts 
+
+	lgdt [gdt]
+        mov ax, DATA_SEG
+        mov ds, ax
+        mov es, ax
+        mov fs, ax
+        mov gs, ax
+        mov ss, ax
+        jmp CODE_SEG:.huita
+
+.huita:
+	push ebx
         call kmain      ;send processor to continue execution from the kamin funtion in c code
 
 
diff --git a/src/gdt.asm b/src/gdt.asm
new file mode 100644
index 0000000..e2ffbb9
--- /dev/null
+++ b/src/gdt.asm
@@ -0,0 +1,30 @@
+gdt_start:
+  ; null entry
+  dd 0
+  dd 0
+
+gdt_code:
+  dw 0xffff    ; 00-15 limit
+  dw 0         ; 16-31 base
+  db 0         ; 32-39 base
+  db 10011010b ; 40-47 access
+  db 11001111b ; 48-55 limit (48-51) and flags (52-55)
+  db 0         ; 56-63 base
+
+gdt_data:
+  dw 0xffff    ; 00-15 limit
+  dw 0         ; 16-31 base
+  db 0         ; 32-39 base
+  db 10010010b ; 40-47 access
+  db 11001111b ; 48-55 limit (48-51) and flags (52-55)
+  db 0         ; 56-63 base
+
+gdt_end:
+
+
+gdt:
+  dw gdt_end - gdt_start - 1 ; length
+  dd gdt_start               ; address
+
+CODE_SEG equ gdt_code - gdt_start
+DATA_SEG equ gdt_data - gdt_start
diff --git a/src/kernel.c b/src/kernel.c
index f161a37..0e43166 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -12,7 +12,7 @@ void kmain()
 {
 	terminal_initialize();
 	printf("KatauOS booting up\n");
-	gdt_install();
+//	gdt_install();
 	isr_install();
 	printf("Kernel init sequence completed\n");