From 523bff7fce18544f713a71b9419af8d4ab9fa328 Mon Sep 17 00:00:00 2001
From: Mathieu Maret <mathieu.maret@gmail.com>
Date: Fri, 24 Nov 2017 22:32:11 +0100
Subject: [PATCH] Put 32bits code after 1sector and load it

Use makefile to build
Use ld linker script to create final bin
---
 Makefile  | 23 +++++++++++++++++++++++
 Readme.md |  4 ++--
 linker.ld | 26 ++++++++++++++++++++++++++
 mbr.asm   | 31 ++++++++++++++++++++++---------
 4 files changed, 73 insertions(+), 11 deletions(-)
 create mode 100644 Makefile
 create mode 100644 linker.ld

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..b244601
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,23 @@
+AS=nasm
+ASFLAGS += -f elf32
+LDFLAGS += -m32 -nostdlib -static -fno-common -fno-use-cxa-atexit -fno-exceptions -fno-non-call-exceptions -fno-weak -fno-rtti
+CFLAGS += -m32 -Wall -Wextra -Werror -ffreestanding  -fno-exceptions
+CXXFLAGS += -m32 -Wall -Wextra -Werror -ffreestanding  -fno-exceptions -fno-rtti
+
+
+asmsrc=$(wildcard *.asm)
+asmobj=$(asmsrc:%.asm=%.o)
+csrc=$(wildcard *.c)
+cobj=$(csrc:%.c=%.o)
+
+kernel:$(asmobj) $(cobj) linker.ld
+	$(CXX) $(LDFLAGS) $(cobj) $(asmobj) -o $@ -T linker.ld
+
+%.o:%.asm
+	$(AS) $(ASFLAGS) -o $@ $<
+
+test:kernel
+	qemu-system-x86_64 -fda $<
+
+clean:
+	$(RM) kernel $(asmobj) $(cobj)
diff --git a/Readme.md b/Readme.md
index 1b8c973..8e27a7b 100644
--- a/Readme.md
+++ b/Readme.md
@@ -1,10 +1,10 @@
 # Instruction
 
 Build with
- `nasm -f bin mbr.asm -o mbr`
+ `make`
 
 Run with
- `qemu-system-x86_64 -boot a -fda  mbr`
+ `make test`
 
 Debug with
  `qemu-system-x86_64 -boot a -fda  mbr -s -S`
diff --git a/linker.ld b/linker.ld
new file mode 100644
index 0000000..19d67b2
--- /dev/null
+++ b/linker.ld
@@ -0,0 +1,26 @@
+ENTRY(boot)
+OUTPUT_FORMAT("binary")
+SECTIONS {
+	. = 0x7c00;
+	.text :
+	{
+		*(.boot)
+		*(.text)
+	}
+
+	.rodata :
+	{
+		*(.rodata)
+	}
+
+	.data :
+	{
+		*(.data)
+	}
+
+	.bss :
+	{
+		*(.bss)
+	}
+}
+
diff --git a/mbr.asm b/mbr.asm
index 2060fae..bc1ff9d 100644
--- a/mbr.asm
+++ b/mbr.asm
@@ -1,7 +1,8 @@
-bits 16				; mode 16bits
-org 0x7C00			; mbr ae loaded at 0x7C00
-
-jmp boot
+section .boot
+bits 16
+global boot
+boot:
+	jmp main
 
 display_enable:
     push bp
@@ -57,8 +58,9 @@ println:
 hello db 'Hello world', 0
 name db 'This is a name', 0
 
-boot:
+main:
     sti             ; enable virtual interupts
+    mov [disk],dl   ; save disk used to boot by bios
 
     call display_enable
 
@@ -81,6 +83,15 @@ boot:
     mov ax, 0x3
     int 0x10
 
+    ; Bios read first 512 bytes, read next disk sector
+    mov ah, 0x2    ;read sectors
+    mov al, 6      ;sectors to read
+    mov ch, 0      ;cylinder idx
+    mov dh, 0      ;head idx
+    mov cl, 2      ;sector idx
+    mov dl, [disk] ;disk idx
+    mov bx, copy_target;target pointer
+    int 0x13
 
     cli ; clear interruption flag
 
@@ -113,10 +124,14 @@ gdt_end:
 gdt_pointer:
 	dw gdt_end - gdt_start
 	dd gdt_start
-
+disk:
+	db 0x0
 CODE_SEG equ gdt_code - gdt_start
 DATA_SEG equ gdt_data - gdt_start
 
+times 510 - ($-$$) db 0
+dw 0xaa55
+copy_target:
 bits 32
 boot2:
 	mov ax, DATA_SEG
@@ -139,6 +154,4 @@ boot2:
 halt:
 	cli
 	hlt
-hello32: db "Hello world!",0
-times 510 - ($ - $$) db 0	; fill up to 510 with 0
-dw 0xAA55			; MBR magic number
+hello32: db "Hello 32 bits world!",0