From 36bbfd9184426576d38841bcabfa5ba2b59f726c Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Sat, 14 Sep 2019 17:05:06 +0200
Subject: Added very basic kernel and vga driver

---
 src/boot.s | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 src/boot.s

(limited to 'src/boot.s')

diff --git a/src/boot.s b/src/boot.s
new file mode 100644
index 0000000..6cb2f7c
--- /dev/null
+++ b/src/boot.s
@@ -0,0 +1,41 @@
+// Constants for the multiboot header
+.set ALIGN, 1<<0
+.set MEMINFO, 1<<1
+.set FLAGS, ALIGN | MEMINFO
+.set MAGIC, 0x1BADB002
+.set CHECKSUM, -(MAGIC + FLAGS)
+
+// Header marking the program as kernel
+.section .multiboot
+.align 4
+.long MAGIC
+.long FLAGS
+.long CHECKSUM
+
+// Initialize a small stack
+.section .bss
+.align 16
+stack_bottom:
+.skip 16384 // 16 KiB
+stack_top:
+
+// Use _start from linker as starting point
+.section .text
+.global _start
+.type _start, @function
+_start:
+	// Set up stack by setting esp to top of stack
+	mov $stack_top, %esp
+
+	// TODO: Initialize processor, load GDT, enable paging
+
+	// Call the kernel
+	call kernel_main
+
+	// Put the system in an infinite loop
+	cli
+1:	hlt
+	jmp 1b
+
+// Set the size of the _start symbol to the current location '.' minus its start
+.size _start, . - _start
-- 
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