From c185345dd341ce4412a169085ab09ca85b017268 Mon Sep 17 00:00:00 2001
From: Alex Kotov <kotovalexarian@gmail.com>
Date: Thu, 27 Jan 2022 23:09:49 +0500
Subject: [PATCH] Split into sections

---
 build.sh          |  7 +++++--
 src/x86/stage1.S  | 18 ++++++------------
 src/x86/stage1.ld |  2 ++
 src/x86/stage2.S  |  9 +++------
 src/x86/stage2.ld |  2 ++
 src/x86/start.S   | 11 +++++++++++
 6 files changed, 29 insertions(+), 20 deletions(-)
 create mode 100644 src/x86/start.S

diff --git a/build.sh b/build.sh
index 27cef5b..db09cec 100755
--- a/build.sh
+++ b/build.sh
@@ -8,9 +8,12 @@ CROSS="$BIN/i386-elf-"
 
 ./clean.sh
 
+${CROSS}gcc -c $SRC/start.S  -o $SRC/start.o
 ${CROSS}gcc -c $SRC/stage1.S -o $SRC/stage1.o
 ${CROSS}gcc -c $SRC/stage2.S -o $SRC/stage2.o
-${CROSS}ld -T$SRC/stage1.ld -o $SRC/stage1.bin $SRC/stage1.o
-${CROSS}ld -T$SRC/stage2.ld -o $SRC/stage2.bin $SRC/stage2.o
+
+${CROSS}ld -T$SRC/stage1.ld -o $SRC/stage1.bin $SRC/start.o $SRC/stage1.o
+${CROSS}ld -T$SRC/stage2.ld -o $SRC/stage2.bin $SRC/start.o $SRC/stage2.o
+
 ./testyboot mbr mbr.bin $SRC/stage1.bin
 cat mbr.bin $SRC/stage2.bin > disk.img
diff --git a/src/x86/stage1.S b/src/x86/stage1.S
index 02b604a..c462628 100644
--- a/src/x86/stage1.S
+++ b/src/x86/stage1.S
@@ -4,18 +4,12 @@
 
 #define STACK_BASE  0x2000
 #define STAGE2_BASE 0x7e00
-
-#define DIST(x) (x - _start)
-
-#define STAGE2_ADDR(x) (DIST(x) + STAGE2_BASE)
+#define STAGE2_SIZE 0x7e06
 
 .code16
-.global _start
-
-.section .text
-_start:
-    ljmp $0, $main
+.global init
 
+.section .init
 .align 2
 size: .word 0
 
@@ -29,7 +23,7 @@ parenth: .string " ("
 of: .string " of "
 to_address: .string ") to address "
 
-main:
+init:
     cli
     xor %ax, %ax
     mov %ax, %ss
@@ -58,14 +52,14 @@ main:
     mov $STAGE2_BASE, %bx // Address
     int $0x13
 
-    mov $STAGE2_ADDR(size), %bx
+    mov $STAGE2_SIZE, %bx
     mov (%bx), %ax
     call print_stage2_size
 
     // DX - dividend high (always zero)
     xor %dx, %dx
     // AX - dividend low
-    mov $STAGE2_ADDR(size), %bx
+    mov $STAGE2_SIZE, %bx
     mov (%bx), %ax
     // BX - divisor (always 512)
     mov $512, %bx
diff --git a/src/x86/stage1.ld b/src/x86/stage1.ld
index 44a521e..018a8e5 100644
--- a/src/x86/stage1.ld
+++ b/src/x86/stage1.ld
@@ -11,6 +11,8 @@ SECTIONS
 
     .text :
     {
+        *(.start);
+        *(.init);
         *(.text);
     }
 
diff --git a/src/x86/stage2.S b/src/x86/stage2.S
index 4928252..db06de1 100644
--- a/src/x86/stage2.S
+++ b/src/x86/stage2.S
@@ -3,13 +3,10 @@
 #endif
 
 .code16
-.global _start
+.global init
 .extern program_size
 
-.section .text
-_start:
-    ljmp $0, $main
-
+.section .init
 .align 2
 size: .word program_size
 
@@ -17,7 +14,7 @@ hello2: .string "Hello from stage 2!\r\n"
 hello3: .string "Hello from sector 3!\r\n"
 hello4: .string "Hello from sector 4!\r\n"
 
-main:
+init:
     mov $hello2, %si
     call print_str
 
diff --git a/src/x86/stage2.ld b/src/x86/stage2.ld
index d5cbf88..08399b4 100644
--- a/src/x86/stage2.ld
+++ b/src/x86/stage2.ld
@@ -11,6 +11,8 @@ SECTIONS
 
     .text :
     {
+        *(.start);
+        *(.init);
         *(.text);
     }
 
diff --git a/src/x86/start.S b/src/x86/start.S
new file mode 100644
index 0000000..d4a534d
--- /dev/null
+++ b/src/x86/start.S
@@ -0,0 +1,11 @@
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+.code16
+.global _start
+.extern init
+
+.section .start
+_start:
+    ljmp $0, $init