From 9a2d5cbdc7972d1d5bfb1ea93f82f66d113faa17 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Wed, 7 Jul 2021 19:13:11 +0200
Subject: Strange implementations

---
 src/loader/jmp.asm | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 src/loader/jmp.asm

(limited to 'src/loader/jmp.asm')

diff --git a/src/loader/jmp.asm b/src/loader/jmp.asm
new file mode 100644
index 0000000..f591dda
--- /dev/null
+++ b/src/loader/jmp.asm
@@ -0,0 +1,28 @@
+; MIT License, Copyright (c) 2021 Marvin Borner
+; Exit the bootloader and clear registers
+
+bits 32
+
+; Empty (invalid) idt
+idt:
+	dd 0, 0
+
+global jmp_kernel
+jmp_kernel:
+	cli ; Disable interrupts because of invalid idt
+	lidt [idt] ; Load empty (invalid) idt
+
+	xor eax, eax
+	lldt ax ; Clear LDT by pointing to nothing
+
+	add esp, 4
+	pop edi
+	add esp, 4
+
+	mov eax, 0x00000001
+	mov cr0, eax ; Clear cr0 except protected mode
+
+	xor eax, eax
+	mov cr4, eax ; Clear cr4 completely
+
+	call edi ; Call custom (specified) jumper
-- 
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