From 054efb994fdd39c6a5d5354737ddb32401241fc3 Mon Sep 17 00:00:00 2001
From: acevest <zhaoyanbai@126.com>
Date: Sat, 13 Apr 2024 17:35:30 +0800
Subject: [PATCH] =?utf8?q?=E5=B0=86=20multiboot2=20=E7=9A=84=20header=20?=
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---
 boot/multiboot.S | 23 ++++++++++++++++++-----
 scripts/link.ld  | 16 +++++++++-------
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/boot/multiboot.S b/boot/multiboot.S
index da41886..0d43837 100644
--- a/boot/multiboot.S
+++ b/boot/multiboot.S
@@ -30,13 +30,20 @@
 
 #define MULTIBOOT_STACK_SIZE 0x4000
 
-.text
-.code32
-.align 32
+.section .kernel_entry_text
 kernel_entry:
 main:
     cli
+    jmp real_kernel_entry
 
+#
+# 这之间放multiboot2_header
+#
+
+.text
+.code32
+.align 4
+real_kernel_entry:
     # Load GDT's Information To GDTR
     lgdt    GDTR-KRNLADDR
 
@@ -155,8 +162,14 @@ GDTR:
 
 
 .section .multiboot2_header
-# section align 64 bits boundary
-.align 64
+# An OS image must contain an additional header called Multiboot2 header,
+# besides the headers of the format used by the OS image.
+# The Multiboot2 header must be contained completely within the first 32768 bytes of the OS image,
+# and must be 64-bit aligned.
+# In general, it should come as early as possible,
+# and may be embedded in the beginning of the text segment after the real executable header.
+# 64-bit 对齐 就是 8 字节对齐
+.align 8
 multiboot2_header_bgn:
     # magic
     .long MULTIBOOT2_HEADER_MAGIC
diff --git a/scripts/link.ld b/scripts/link.ld
index 7d6272c..5736596 100644
--- a/scripts/link.ld
+++ b/scripts/link.ld
@@ -1,16 +1,16 @@
 /*
  *--------------------------------------------------------------------------
  *   File Name: link.ld
- * 
+ *
  * Description: Link All Object Files to KERNEL ...
- * 
- * 
+ *
+ *
  *      Author: Zhao Yanbai [zhaoyanbai@126.com]
- * 
+ *
  *     Version: 1.1
  * Create Date: Mon Mar  2 12:21:03 2009
  * Last Update: Mon Mar  2 12:21:03 2009
- * 
+ *
  *--------------------------------------------------------------------------
  */
 
@@ -26,14 +26,16 @@ SECTIONS
     {
         code = .;
         phys_addr = . - kernel_virtual_addr_start;
-        boot/multiboot.S.o(.text)
+        *(.kernel_entry_text)
         *(.multiboot2_header)
+        /* 单独把 multiboot.S 的 .text 放在这个位置是为了便于调试，实际是可以不写这一句的 */
+        boot/multiboot.S.o(.text)
         *(.text)
         *(.ring3.text);
         *(.sysexit) /* last */
     }
     etext = .;
-    .data : AT(phys_addr) ALIGN(0x1000) 
+    .data : AT(phys_addr) ALIGN(0x1000)
     {
         data = .;
         phys_addr = . - kernel_virtual_addr_start;
-- 
2.44.0