From ba7e57138c9e41cf944afb91c146fea23713c1d1 Mon Sep 17 00:00:00 2001
From: Loic Guegan <manzerbredes@mailbox.org>
Date: Mon, 5 Apr 2021 14:46:31 +0200
Subject: Reload GDT

---
 src/boot/boot.S | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

(limited to 'src/boot')

diff --git a/src/boot/boot.S b/src/boot/boot.S
index 746f858..e3830eb 100644
--- a/src/boot/boot.S
+++ b/src/boot/boot.S
@@ -1,4 +1,5 @@
 .extern bringelle
+.extern gdt_memcpy
 .globl  _start
 .text
 
@@ -23,5 +24,28 @@ mb_header:
 .long MB_ENTRY_ADDR
 
 _start:
-    call bringelle
+
+# Copy GDT into memory then load its register
+call gdt_memcpy
+lgdtl (GDTR)
+
+# Update all segments register
+# with the new GDT offset
+movw $0x10, %ax
+movw %ax, %ds
+movw %ax, %es
+movw %ax, %fs
+movw %ax, %gs
+
+# Update code segment
+ljmp $0x08, $cs_new
+cs_new:
+
+# Update stack segment
+movw $0x18, %ax
+movw %ax, %ss
+movl $0x20000,%esp
+
+# Start kernel main function
+call bringelle
 
-- 
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