From 7adc0c7ce11c6c46c5e6c4cb01a94af1edb6b6d5 Mon Sep 17 00:00:00 2001
From: Robert <robert.altner@einweckglas.com>
Date: Sun, 3 Sep 2023 20:11:33 +0200
Subject: [PATCH] port clipper to boot using grub
---
Makefile | 44 ++++-----
grub/grub.cfg | 3 +
linker.ld | 28 ++++++
src/boot/boot.asm | 217 ------------------------------------------
src/kernel/boot.asm | 36 +++++++
src/kernel/kernel.asm | 0
src/kernel/kmain.c | 15 +++
7 files changed, 104 insertions(+), 239 deletions(-)
create mode 100644 grub/grub.cfg
create mode 100644 linker.ld
delete mode 100644 src/boot/boot.asm
create mode 100644 src/kernel/boot.asm
delete mode 100644 src/kernel/kernel.asm
create mode 100644 src/kernel/kmain.c
diff --git a/Makefile b/Makefile
index 9302292..697e49f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,37 +1,37 @@
ASM=nasm
+CC=$(HOME)/opt/cross/bin/i686-elf-gcc
SRC_DIR=src
BUILD_DIR=build
+ISO_DIR=$(BUILD_DIR)/iso
-BOOT_FILES = $(shell find $(SRC_DIR)/boot/ -type f -name "*.asm")
-KERN_ASM_FILES = $(shell find $(SRC_DIR)/kernel/ -type f -name "*.asm")
+KERNEL_ASM := $(shell find $(SRC_DIR)/kernel -name "*.asm")
+KERNEL_C := $(shell find $(SRC_DIR)/kernel -name "*.c")
-BOOT_BIN_FILES = $(patsubst src/%.asm, $(BUILD_DIR)/%.bin, $(BOOT_FILES))
-KERN_BIN_FILES = $(patsubst src/%.asm, $(BUILD_DIR)/%.bin, $(KERN_ASM_FILES))
+KERNEL_ASM_O := $(patsubst $(SRC_DIR)/kernel/%.asm, $(BUILD_DIR)/kernel/%.asm.o, $(KERNEL_ASM))
+KERNEL_C_O := $(patsubst $(SRC_DIR)/kernel/%.c, $(BUILD_DIR)/kernel/%.c.o, $(KERNEL_C))
-BOOTLOADER = $(BUILD_DIR)/boot.bin
-KERNEL = $(BUILD_DIR)/kernel.bin
-IMAGE = $(BUILD_DIR)/clipper.img
+KERNEL = $(BUILD_DIR)/clipper.bin
+IMAGE = $(BUILD_DIR)/clipper.iso
-.PHONY: all clipper kernel bootloader clean always
+.PHONY: all clipper kernel clean always
-clipper: $(IMAGE)
+clipper: kernel
+ mkdir -p $(ISO_DIR)/boot/grub
+ cp $(KERNEL) $(ISO_DIR)/boot/clipper.bin
+ cp grub/grub.cfg $(ISO_DIR)/boot/grub/grub.cfg
+ grub-mkrescue -o $(IMAGE) $(ISO_DIR)
-$(IMAGE): bootloader kernel
- dd if=/dev/zero of=$(IMAGE) bs=512 count=2880
- mkfs.fat -F 12 -n "CLPR" $(IMAGE)
- dd if=$(BOOTLOADER) of=$(IMAGE) conv=notrunc
- mcopy -i $(IMAGE) $(KERNEL) "::kernel.bin"
+kernel: $(KERNEL_ASM_O) $(KERNEL_C_O)
+ $(CC) -T linker.ld -o $(KERNEL) -ffreestanding -O2 -nostdlib $^ -lgcc
-bootloader: $(BOOT_BIN_FILES)
- cp $(BUILD_DIR)/boot/boot.bin $(BOOTLOADER)
-
-kernel: $(KERN_BIN_FILES)
- cp $(BUILD_DIR)/kernel/kernel.bin $(KERNEL)
-
-$(BUILD_DIR)/%.bin: $(SRC_DIR)/%.asm
+$(BUILD_DIR)/%.asm.o: $(SRC_DIR)/%.asm
@mkdir -p "$(@D)"
- $(ASM) $< -f bin -o $@
+ $(ASM) -felf32 $< -o $@
+
+$(BUILD_DIR)/%.c.o: $(SRC_DIR)/%.c
+ @mkdir -p "$(@D)"
+ $(CC) -c $< -o $@ -std=gnu99 -ffreestanding -O2 -Wall -Wextra
clean:
rm -rf $(BUILD_DIR)/*
diff --git a/grub/grub.cfg b/grub/grub.cfg
new file mode 100644
index 0000000..a61dd4a
--- /dev/null
+++ b/grub/grub.cfg
@@ -0,0 +1,3 @@
+menuentry "clipper" {
+ multiboot /boot/clipper.bin
+}
diff --git a/linker.ld b/linker.ld
new file mode 100644
index 0000000..0e93f9b
--- /dev/null
+++ b/linker.ld
@@ -0,0 +1,28 @@
+ENTRY(_start)
+
+SECTIONS
+{
+ . = 1M;
+
+ .text BLOCK(4K) : ALIGN(4K)
+ {
+ *(.multiboot)
+ *(.text)
+ }
+
+ .rodata BLOCK(4K) : ALIGN(4K)
+ {
+ *(.rodata)
+ }
+
+ .data BLOCK(4K) : ALIGN(4K)
+ {
+ *(.data)
+ }
+
+ .bss BLOCK(4K) : ALIGN(4K)
+ {
+ *(COMMON)
+ *(.bss)
+ }
+}
diff --git a/src/boot/boot.asm b/src/boot/boot.asm
deleted file mode 100644
index d71a580..0000000
--- a/src/boot/boot.asm
+++ /dev/null
@@ -1,217 +0,0 @@
-org 0x7C00
-bits 16
-
-%define ENDL 0x0D, 0x0A
-
-; FAT 12 BIOS PARAMETER BLOCK
-jmp short start
-nop
-bpb_oem: db "CLPROS01"
-bpb_bytes_per_sector: dw 512
-bpb_sectors_per_cluster: db 1
-bpb_reserved_sectors: dw 1
-bpb_fat_count: db 2
-bpb_dir_entries_count: dw 0E0h
-bpb_total_sectors: dw 2880
-bpb_media_descriptor_type: db 0F0h
-bpb_sectors_per_fat: dw 9
-bpb_sectors_per_track: dw 18
-bpb_heads: dw 2
-bpb_hidden_sectors: dd 0
-bpb_large_sector_count: dd 0
-
-; EXTENDED BOOT RECORD
-ebr_drive_number: db 0
- db 0
-ebr_signature: db 28h
-ebr_volume_id: db 63h, 6Ch, 70h, 72h
-ebr_volume_label: db "Clipper "
-ebr_system_identifier: db "FAT12 "
-
-start:
- jmp main
-
-;
-; Prints a string to the screen
-; Params:
-; - ds:si points to string
-puts:
- push si
- push ax
-
- mov ah, 0Eh
-
-.loop:
- lodsb ; load byte at ds:si into al
- or al, al ; is null?
- jz .done
-
- int 10h
- jmp .loop
-
-.done:
- pop si
- pop ax
- ret
-
-
-main:
- ; setup data segment
- mov ax, 0
- mov ds, ax
- mov es, ax
-
- ; setup stack
- mov ss, ax
- mov sp, 0x7C00
-
- ; print message
- mov si, msg_hello
- call puts
-
- ; read something from disk
- mov [ebr_drive_number], dl
- mov ax, 1
- mov cl, 1
- mov bx, 0x7E00
- call disk_read
-
- mov di, 0
- mov cl, [ebr_drive_number]
-.loop:
- xor ch, ch
- shl cx, 4
- add ch, 30h
- test cx, 9
- jle .write_disk_number
- add ch, 11h
-
-.write_disk_number:
- mov byte [msg_drive_number_value + di], ch
- inc di
- cmp di, 2
- jne .loop
-
- mov si, msg_drive_number
- call puts
-
- hlt
- jmp halt
-
-floppy_error:
- mov si, msg_read_failed
- call puts
- jmp wait_key_and_reboot
-
-wait_key_and_reboot:
- mov ah, 0
- int 16h
- jmp 0FFFFh:0
- hlt
-
-halt:
- cli
- hlt
-
-;
-; Convert LBA address to CHS
-; Parameters:
-; - ax: LBA address
-; Returns:
-; - cx [bits 0-5]: sector
-; - cx [bits 6-15]: cylinder
-; - dh: head
-;
-lba_to_chs:
- push ax
- push dx
-
- xor dx, dx
- div word [bpb_sectors_per_track]
-
- inc dx
- mov cx, dx
-
- xor dx, dx
- div word [bpb_heads]
-
- mov dh, dl
- mov ch, al
- shl ah, 6
- or cl, ah
-
- pop ax
- mov dl, al
- pop ax
- ret
-
-;
-; Reads from disk
-; Parameters:
-; - ax: LBA address
-; - cl: number of sectors to read (max 128)
-; - dl: drive number
-; - es:bx: memory address where to store data
-;
-disk_read:
- push ax
- push bx
- push cx
- push dx
- push di
-
- push cx
- call lba_to_chs
- pop ax
-
- mov ah, 02h
- mov di, 3
-
-.retry:
- pusha
- stc
- int 13h
- jnc .done
-
- popa
- call disk_reset
-
- dec di
- jnz .retry
-
-.fail:
- jmp floppy_error
-
-.done:
- popa
-
- pop di
- pop dx
- pop cx
- pop bx
- pop ax
- ret
-
-;
-; Resets a disk controller
-; Parameters:
-; dl: drive number
-;
-disk_reset:
- pusha
- mov ah, 0
- stc
- int 13h
- jc floppy_error
- popa
- ret
-
-
-msg_hello: db "Hello, Clipper!", ENDL, 0
-msg_read_failed: db "Failed to read from disk.", ENDL, 0
-msg_drive_number: db "Disk number: "
-msg_drive_number_value: dw 0
-msg_drive_number_end: db ENDL, 0
-
-times 510-($-$$) db 0
-dw 0AA55h
diff --git a/src/kernel/boot.asm b/src/kernel/boot.asm
new file mode 100644
index 0000000..d3ef922
--- /dev/null
+++ b/src/kernel/boot.asm
@@ -0,0 +1,36 @@
+;
+; Bootstrap code for the Clipper operating system
+;
+
+MBALIGN equ 1 << 0
+MEMINFO equ 1 << 1
+FLAGS equ MBALIGN | MEMINFO
+MAGIC equ 0x1BADB002
+CHECKSUM equ -(MAGIC + FLAGS)
+
+; multiboot header
+section .multiboot
+align 4
+ dd MAGIC
+ dd FLAGS
+ dd CHECKSUM
+
+section .bss
+align 16
+stack_bottom:
+ resb 16384
+stack_top:
+
+section .text
+global _start: function (_start.end - _start)
+_start:
+ mov esp, stack_top
+
+ extern kmain
+ call kmain
+
+ cli
+.hang:
+ hlt
+ jmp .hang
+.end:
diff --git a/src/kernel/kernel.asm b/src/kernel/kernel.asm
deleted file mode 100644
index e69de29..0000000
diff --git a/src/kernel/kmain.c b/src/kernel/kmain.c
new file mode 100644
index 0000000..b146843
--- /dev/null
+++ b/src/kernel/kmain.c
@@ -0,0 +1,15 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#if defined(__linux__)
+# error "Please use a platform agnostic compiler"
+#endif
+
+#if !defined(__i386__)
+# error "Please use an ix86-elf compiler"
+#endif
+
+void kmain(void) {
+ return;
+}