From aa814a9c8a58208be5e0de0612165c96fdac6419 Mon Sep 17 00:00:00 2001
From: Recolic Keghart <root@recolic.net>
Date: Tue, 9 Jun 2020 16:26:52 +0800
Subject: [PATCH] add kern loader, debugging
---
Makefile | 4 ++++
bootloader/boot.asm | 38 +++++++++++++++++++++++++++++++++++---
kernel/Makefile | 4 +++-
3 files changed, 42 insertions(+), 4 deletions(-)
diff --git a/Makefile b/Makefile
index 303a82f..b5bd258 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,14 @@
+default: assemble
+
bootloader:
$(MAKE) -C bootloader
kernel:
$(MAKE) -C kernel
+.PHONY: bootloader kernel
+
build: bootloader kernel
assemble: build
diff --git a/bootloader/boot.asm b/bootloader/boot.asm
index 43313ea..389dee9 100644
--- a/bootloader/boot.asm
+++ b/bootloader/boot.asm
@@ -1,6 +1,7 @@
[bits 16]
[org 0x7c00]
+mov [_boot_drive_id], dl
jmp _init_prot_mode
gdt_begin:
@@ -61,14 +62,45 @@ _prot_begin:
mov ebx, _motd_32
call println_vga
- KERN_ADDR equ 0x1000
+ ; Load the kernel image from boot disk, disk offset 512B to 64KB.
+ KERN_ADDR equ 0x7e00
+ mov ah, 0x02
+ mov ch, 0
+ mov dh, 0
+ mov cl, 2 ; from the second one,
+ mov al, 127 ; read 127 sectors in total.
+ mov bx, KERN_ADDR
+ int 0x13 ; Set carry on error, and set AL to sectors that actual read.
+ jmp _stall
+
+ jc disk_io_error
+ mov dl, 0x7f
+ cmp dl, al
+ jne disk_io_error
+ ; kernel successfully loaded now!
+ mov ebx, _motd_kern_ok
+ call println_vga
+
+
+_stall:
jmp $
+disk_io_error:
+ mov ebx, _motd_disk_error
+ call println_vga
+ jmp _stall
+
+_motd_disk_error:
+ db 'DISK_IO_ERROR', 0x0
_motd_32:
- db '[ENTER X86 MODE SUCC] [LOADING KERN..]', 0x0
+ db '[ENTER X86 MODE SUCC]', 0x0
+_motd_kern_ok:
+ db '[ENTER X86 MODE SUCC] [LOAD KERN SUCC]', 0x0
_motd_endk:
- db '[ENTER X86 MODE SUCC] [LOADING KERN..] [KERN EXITED]', 0x0
+ db '[ENTER X86 MODE SUCC] [LOAD KERN SUCC] [KERN EXITED]', 0x0
+_boot_drive_id:
+ db 0x0
%include "./mbr_end.inc"
diff --git a/kernel/Makefile b/kernel/Makefile
index b712a80..6d07b25 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -1,7 +1,9 @@
kernel:
gcc -ffreestanding -c kernel.c -o kernel.o # -m32
- ld -o kernel.img -Ttext 0x1000 --oformat binary kernel.o # -m elf_i386
+ ld -o kernel.img -Ttext 0x7e00 --oformat binary kernel.o # -m elf_i386
+ # Sector 1 = bootloader, Sector 2 - (512B TO 64K) = kernel
+ truncate --size=65024 kernel.img
clean:
rm *.o *.img
--
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