rearraged files, set up to use grub bootloader

.gitignore

@@ -1,8 +1,11 @@
 *.iso
-isodir
+*.img
-sysroot
+*.o
+*.bin
+*.elf
 
 .idea
 .vscode
 
 build
+isodir

boot/boot.ld

@@ -1,14 +0,0 @@
-ENTRY(_start)
-
-SECTIONS
-{
-  . = 0x7C00;
-
-  .text : {
-    *(.text)
-  }
-
-  .data : { 
-    *(.data)
-  }
-}

boot/boot.s

@@ -1,129 +0,0 @@
-.code16
-.text
-.global _start
-_start:
-	ljmp $0x07C0, $something
-
-something:
-	cli
-	cld
-
-	mov %cs, %ax
-	mov %ax, %ds
-	mov %ax, %es
-
-	# stack stuff
-	mov $0x0000, %ax
-	mov %ax, %ss
-	mov $0xFFF0, %sp
-
-	# copy the first 12 bytes of our MBR table entry
-	mov %dl, (disk_number)
-	mov $mbr_entry, %di
-	mov $12, %cx
-	rep movsb
-
-	mov $0, %ah
-	int $0x13
-	
-	mov $0x08, %ah
-	int $0x13
-	and 0b00111111, %cl
-	mov %cl, (total_sectors)
-	mov %ch, (total_cylinders)
-	mov %dh, (total_heads)
-
-	mov $0x1000, %ax
-	mov %ax, %es
-	mov $0x0000, %bx
-
-	mov (disk_number), %dl
-	mov $0, %ch #cylinder
-	mov $0, %dh #head
-	mov $2, %cl #sector
-
-load_sector:
-	mov $1, %al
-	mov $0x02, %ah
-	int $0x13
-
-	mov (kernel_sectors), %ax
-	cmp $0xffff, %ax
-	jne check_last_sector
-	mov %es:20, %eax
-	shr $9, %eax
-	inc %eax
-
-check_last_sector:
-	dec %ax
-	mov %ax, kernel_sectors
-	cmp $0, %ax
-	je done
-
-move: # inc our offset. If it hits 0, we've moved a segment, inc that too.
-	add $512, %bx
-	cmp $0, %bx
-	jnz read_next_sector
-	mov %es, %ax
-	add $1000, %ax
-	mov %ax, %es
-
-read_next_sector: # find the next valid sector, head, cylinder combo on the disk
-	inc %cl
-	mov (total_sectors), %al
-	cmp %al, %cl
-	jle load_sector
-	mov $1, %cl #go back to sector 1.. of the next head
-
-	inc %dh #next head
-	mov (total_heads), %al
-	cmp %al, %dh
-	jle load_sector
-	mov $0, %dh # go back to head 0.. of the next cylinder
-
-	inc %ch # next cylinder
-	mov (total_cylinders), %al
-	cmp %al, %ch
-	jle load_sector
-	# no more disk... fall through
-done:
-	mov $0, %ah
-	int $0x13
-
-	mov $0x1000, %ax
-	mov %ax, %ds
-	ljmp $0x1000, $0x0000
-
-disk_number:
-	.byte 0
-total_cylinders:
-	.byte 0
-total_heads:
-	.byte 0
-total_sectors:
-	.byte 0
-
-kernel_sectors:
-	.word 0xFFFF
-
-mbr_entry:
-partition_status:
-	.byte 0
-partition_start_chs:
-	.byte 0
-	.byte 0
-	.byte 0
-partition_type:
-	.byte 0
-partition_stop_chs:
-	.byte 0
-	.byte 0
-	.byte 0
-partition_start_lba:
-	.long 0
-partition_start_length:
-	.long 0
-
-.org 510
-magic:
-	.word 0xAA55

compile_commands.json

@@ -1,45 +1,19 @@
 [
   {
-    "file": "boot.s",
+    "file": "kernel/kmain.c",
     "arguments": [
       "/home/slinky/opt/cross/bin/i686-elf-gcc",
-      "-m32",
       "-c",
-      "boot.s",
+      "kernel/kmain.c",
       "-o",
-      "boot.o"
+      "obj/kernel/kmain.o",
-    ],
-    "directory": "/home/slinky/source/RockOS",
-    "output": "boot.o"
-  },
-  {
-    "file": "prekernel.s",
-    "arguments": [
-      "/home/slinky/opt/cross/bin/i686-elf-gcc",
-      "-m32",
-      "-c",
-      "prekernel.s",
-      "-o",
-      "prekernel.o"
-    ],
-    "directory": "/home/slinky/source/RockOS",
-    "output": "prekernel.o"
-  },
-  {
-    "file": "kmain.c",
-    "arguments": [
-      "/home/slinky/opt/cross/bin/i686-elf-gcc",
-      "-m32",
       "-ffreestanding",
       "-O2",
       "-Wall",
       "-Wextra",
-      "-c",
+      "-Ikernel"
-      "kmain.c",
-      "-o",
-      "kmain.o"
     ],
     "directory": "/home/slinky/source/RockOS",
-    "output": "kmain.o"
+    "output": "obj/kernel/kmain.o"
   }
 ]

grub.cfg

@@ -0,0 +1,3 @@
+menuentry "RockOS" {
+	multiboot /boot/rockos
+}

kernel/boot/boot.s

@@ -0,0 +1,28 @@
+.set ALIGN,    1<<0             /* align loaded modules on page boundaries */
+.set MEMINFO,  1<<1             /* provide memory map */
+.set FLAGS,    ALIGN | MEMINFO  /* this is the Multiboot 'flag' field */
+.set MAGIC,    0x1BADB002       /* 'magic number' lets bootloader find the header */
+.set CHECKSUM, -(MAGIC + FLAGS) /* checksum of above, to prove we are multiboot */
+
+.section .multiboot
+.align 4
+.long MAGIC
+.long FLAGS
+.long CHECKSUM
+
+.section .bss
+.align 16
+stack_bottom:
+.skip 16384 # 16 KiB
+stack_top:
+
+.section .text
+.global _start
+.type _start, @function
+_start:
+	mov $stack_top, %esp
+	call kernel_main
+
+	cli
+1:	hlt
+	jmp 1b

kernel/drivers/vga_stream_writer.c

@@ -0,0 +1,72 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#include <lib/stream.h>
+
+#define VGA_WIDTH   80
+#define VGA_HEIGHT  25
+#define VGA_MEMORY  0xB8000 
+
+enum vga_color {
+	VGA_COLOR_BLACK = 0,
+	VGA_COLOR_BLUE = 1,
+	VGA_COLOR_GREEN = 2,
+	VGA_COLOR_CYAN = 3,
+	VGA_COLOR_RED = 4,
+	VGA_COLOR_MAGENTA = 5,
+	VGA_COLOR_BROWN = 6,
+	VGA_COLOR_LIGHT_GREY = 7,
+	VGA_COLOR_DARK_GREY = 8,
+	VGA_COLOR_LIGHT_BLUE = 9,
+	VGA_COLOR_LIGHT_GREEN = 10,
+	VGA_COLOR_LIGHT_CYAN = 11,
+	VGA_COLOR_LIGHT_RED = 12,
+	VGA_COLOR_LIGHT_MAGENTA = 13,
+	VGA_COLOR_LIGHT_BROWN = 14,
+	VGA_COLOR_WHITE = 15,
+};
+
+size_t terminal_row;
+size_t terminal_column;
+uint8_t terminal_color;
+uint16_t* terminal_buffer = (uint16_t*)VGA_MEMORY;
+
+static inline uint8_t vga_entry_color(enum vga_color fg, enum vga_color bg) 
+{
+	return fg | bg << 4;
+}
+
+static inline uint16_t vga_entry(unsigned char uc, uint8_t color) 
+{
+	return (uint16_t) uc | (uint16_t) color << 8;
+}
+
+void vga_initialize() 
+{
+	terminal_row = 0;
+	terminal_column = 0;
+	terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
+	
+	for (size_t y = 0; y < VGA_HEIGHT; y++) {
+		for (size_t x = 0; x < VGA_WIDTH; x++) {
+			const size_t index = y * VGA_WIDTH + x;
+			terminal_buffer[index] = vga_entry(' ', terminal_color);
+		}
+	}
+}
+
+void vga_putchar(char c) 
+{
+    const size_t index = terminal_row * VGA_WIDTH + terminal_column;
+    terminal_buffer[index] = vga_entry(c, terminal_color);
+	if (++terminal_column == VGA_WIDTH) {
+		terminal_column = 0;
+		if (++terminal_row == VGA_HEIGHT)
+			terminal_row = 0;
+	}
+}
+
+print_stream_t vga_print_stream = {
+    .putchar = vga_putchar,
+    .trunc = vga_initialize,
+};

kernel/gdt.c

@@ -0,0 +1,62 @@
+#include <stdint.h>
+ 
+#define SEG_DESCTYPE(x)  ((x) << 0x04) // Descriptor type (0 for system, 1 for code/data)
+#define SEG_PRES(x)      ((x) << 0x07) // Present
+#define SEG_SAVL(x)      ((x) << 0x0C) // Available for system use
+#define SEG_LONG(x)      ((x) << 0x0D) // Long mode
+#define SEG_SIZE(x)      ((x) << 0x0E) // Size (0 for 16-bit, 1 for 32)
+#define SEG_GRAN(x)      ((x) << 0x0F) // Granularity (0 for 1B - 1MB, 1 for 4KB - 4GB)
+#define SEG_PRIV(x)     (((x) &  0x03) << 0x05)   // Set privilege level (0 - 3)
+ 
+#define SEG_DATA_RD        0x00 // Read-Only
+#define SEG_DATA_RDA       0x01 // Read-Only, accessed
+#define SEG_DATA_RDWR      0x02 // Read/Write
+#define SEG_DATA_RDWRA     0x03 // Read/Write, accessed
+#define SEG_DATA_RDEXPD    0x04 // Read-Only, expand-down
+#define SEG_DATA_RDEXPDA   0x05 // Read-Only, expand-down, accessed
+#define SEG_DATA_RDWREXPD  0x06 // Read/Write, expand-down
+#define SEG_DATA_RDWREXPDA 0x07 // Read/Write, expand-down, accessed
+#define SEG_CODE_EX        0x08 // Execute-Only
+#define SEG_CODE_EXA       0x09 // Execute-Only, accessed
+#define SEG_CODE_EXRD      0x0A // Execute/Read
+#define SEG_CODE_EXRDA     0x0B // Execute/Read, accessed
+#define SEG_CODE_EXC       0x0C // Execute-Only, conforming
+#define SEG_CODE_EXCA      0x0D // Execute-Only, conforming, accessed
+#define SEG_CODE_EXRDC     0x0E // Execute/Read, conforming
+#define SEG_CODE_EXRDCA    0x0F // Execute/Read, conforming, accessed
+ 
+#define GDT_CODE_PL0 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
+                     SEG_LONG(0)     | SEG_SIZE(1) | SEG_GRAN(1) | \
+                     SEG_PRIV(0)     | SEG_CODE_EXRD
+ 
+#define GDT_DATA_PL0 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
+                     SEG_LONG(0)     | SEG_SIZE(1) | SEG_GRAN(1) | \
+                     SEG_PRIV(0)     | SEG_DATA_RDWR
+ 
+#define GDT_CODE_PL3 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
+                     SEG_LONG(0)     | SEG_SIZE(1) | SEG_GRAN(1) | \
+                     SEG_PRIV(3)     | SEG_CODE_EXRD
+ 
+#define GDT_DATA_PL3 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
+                     SEG_LONG(0)     | SEG_SIZE(1) | SEG_GRAN(1) | \
+                     SEG_PRIV(3)     | SEG_DATA_RDWR
+ 
+uint64_t create_descriptor(uint32_t base, uint32_t limit, uint16_t flag)
+{
+    uint64_t descriptor;
+ 
+    // Create the high 32 bit segment
+    descriptor  =  limit       & 0x000F0000;         // set limit bits 19:16
+    descriptor |= (flag <<  8) & 0x00F0FF00;         // set type, p, dpl, s, g, d/b, l and avl fields
+    descriptor |= (base >> 16) & 0x000000FF;         // set base bits 23:16
+    descriptor |=  base        & 0xFF000000;         // set base bits 31:24
+ 
+    // Shift by 32 to allow for low part of segment
+    descriptor <<= 32;
+ 
+    // Create the low 32 bit segment
+    descriptor |= base  << 16;                       // set base bits 15:0
+    descriptor |= limit  & 0x0000FFFF;               // set limit bits 15:0
+
+    return descriptor;
+}

kernel/globals.c

@@ -0,0 +1,3 @@
+#include <lib/stream.h>
+
+print_stream_t* kout;

kernel/kernel.ld

@@ -1,24 +0,0 @@
-ENTRY(_start)
-
-SECTIONS
-{
-    . = 0x10000;
-
-    .text : {
-      *(.text)
-    }
-
-    .rodata : {
-      *(.rodata)
-    }
-
-    .data : {
-      *(.data)
-    }
-
-    .bss : {
-      *(.bss)
-    }
-
-    _end = .;
-}

kernel/kmain.c

@@ -1,28 +1,12 @@
-#include <stdint.h>
+#include <lib/print.h>
+#include <lib/stream.h>
 
-extern void halt();
+void kernel_main(void) 
-extern void idt_load();
+{
-extern void reboot();
+  extern print_stream_t vga_print_stream;
+  extern print_stream_t* kout;
+  kout = &vga_print_stream;
+  kout->trunc();
 
-typedef struct {
+  kprint("RockOS booting...");
-  uint16_t offset_low;
-  uint16_t selector;
-  uint8_t zero;
-  uint8_t flags;
-  uint16_t offset_high;
-} idt_entry_t __attribute__((packed));
-
-typedef struct {
-  uint16_t limit;
-  uint32_t base;
-} idt_ptr_t;
-
-idt_entry_t idt[256];
-idt_ptr_t idtr;
-
-void load_idt() {}
-
-void kmain() {
-  load_idt();
-  halt();
 }

kernel/lib/print.c

@@ -0,0 +1,11 @@
+#include "print.h"
+#include "stream.h"
+
+extern print_stream_t* kout;
+
+void kprint(const char *str) {
+    while (*str) {
+        kout->putchar(*str);
+        str++;
+    }
+}

kernel/lib/print.h

@@ -0,0 +1,6 @@
+#ifndef KLIBPRINT_H
+#define KLIBPRINT_H
+
+void kprint(const char* str);
+
+#endif

kernel/lib/stream.c

@@ -0,0 +1,3 @@
+#include "stream.h"
+
+print_stream_t* pout;

kernel/lib/stream.h

@@ -0,0 +1,9 @@
+#ifndef KSTREAM_H
+#define KSTREAM_H
+
+typedef struct {
+  void (*putchar)(char c);
+  void (*trunc)();
+} print_stream_t;
+
+#endif

kernel/linker.ld

@@ -0,0 +1,28 @@
+ENTRY(_start)
+
+SECTIONS
+{
+	. = 2M;
+
+	.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)
+	}
+}

kernel/prekernel.s

@@ -1,118 +0,0 @@
-.code16
-.text
-.global _start
-_start:
-	jmp everything
-
-.org 20
-.global kernel_size
-kernel_size:
-	.long _end - _start
-
-everything:
-	mov $0x1000, %ax 
-	mov %ax, %es 
-	mov %ax, %ds
-
-	# reset disk
-	mov $0, %ah
-	int $0x13
-
-	# stop the cursor
-	mov $1, %ah
-	mov $0,%cl
-	mov $0x20,%ch
-	int $0x11
-
-	# get the system memory, if this call fails then halt
-	clc
-	mov $0, %bx
-	mov $0xe801, %ax
-	int $0x15
-	jc halt
-	shr $10, %ax
-	shr $4, %bx
-	add %ax, %bx
-	mov %bx, total_mem_mb-_start
-
-	# vga text mode
-	mov $0x0003, %ax 
-	int $0x10
-	
-enable_a20:
-  #enable the a20 gate
-	inb $0x92, %al
-	orb $2, %al
-	outb %al, $0x92
-prep_protected:
-	cli
-	lgdt gdt_init-_start
-	mov %cr0, %eax
-	or $0x01, %eax
-	mov %eax, %cr0 # protected bit set
-  	ljmpl $8, $protected
-
-halt16:
-  jmp halt16
-
-.code32
-protected:
-	mov $16, %ax
-  	mov %ax, %es
-	mov %ax, %ds
-	mov %ax, %ss
-	mov $5*8, %ax
-	ltr %ax
-	mov $0, %ax
-	mov %ax, %fs
-	mov %ax, %gs
-	mov $0xFFF0, %sp
-	mov $0xFFF0, %bp
-	ljmpl $8, $kmain
-
-# some assembly stubs we can call from the kernel
-
-.global idt_load
-.extern idtr       
-idt_load:
-	lidt idtr
-	ret            
-
-.global reboot
-reboot:
-	cli
-	lidt reboot_struct
-	int $1
-reboot_struct:
-	.word 0
-	.long 0
-
-.global halt
-halt:
-	cli
-	hlt
-	jmp halt
-
-# kernel data structures
-
-.align 16
-.global gdt
-gdt:
-	.word 0,0,0,0
-	.word 0xffff, 0x0000, 0x9a00, 0x00cf
-	.word 0xffff, 0x0000, 0x9200, 0x00cf    
-	.word 0xffff, 0x0000, 0xfa00, 0x00cf   
-	.word 0xffff, 0x0000, 0xf200, 0x00cf  
-	.word 0x0068, (tss-_start), 0x8901, 0x00cf
-gdt_init:
-	.word gdt_init-gdt
-	.long gdt
-
-.align 16
-.global tss
-tss:
-	.long 0
-
-.global total_mem_mb
-total_mem_mb:
-	.word 0

makefile

@@ -1,55 +1,38 @@
 CC = i686-elf-gcc
 LD = i686-elf-ld
-OBJCOPY = i686-elf-objcopy
 
-CFLAGS = -m32 -ffreestanding -O2 -Wall -Wextra -nostdlib
+OSNAME := rockos
-ASFLAGS = -m32
 
-BOOT_DIR   := boot
+C_SOURCES := $(shell find kernel -type f -name '*.c')
-KERNEL_DIR := kernel
+S_SOURCES := $(shell find kernel -type f -name '*.s')
-BUILD_DIR  := build
 
-BOOT_BIN   := $(BUILD_DIR)/boot.bin
+OBJECTS := $(patsubst %.c, obj/%.o, $(C_SOURCES)) $(patsubst %.s, obj/%.o, $(S_SOURCES))
-KERNEL_BIN := $(BUILD_DIR)/kernel.bin
-IMAGE      := os.img
 
-.PHONY: all clean run
+CFLAGS  := -ffreestanding -O2 -Wall -Wextra -Ikernel
+LDFLAGS := -T kernel/linker.ld
 
-all: $(IMAGE)
+.PHONY: all run clean
 
-$(BUILD_DIR)/%.o: $(BOOT_DIR)/%.s | $(BUILD_DIR)
+$(OSNAME).bin: $(OBJECTS)
-	$(CC) $(ASFLAGS) -c $< -o $@
+	$(LD) $(LDFLAGS) -o $@ $(OBJECTS)
 
-$(BUILD_DIR)/%.o: $(KERNEL_DIR)/%.s | $(BUILD_DIR)
+$(OSNAME).iso: $(OSNAME).bin grub.cfg
-	$(CC) $(ASFLAGS) -c $< -o $@
+	mkdir -p isodir/boot/grub
+	cp $(OSNAME).bin isodir/boot/$(OSNAME)
+	cp grub.cfg isodir/boot/grub/grub.cfg
+	grub-mkrescue -o $(OSNAME).iso isodir
 
-$(BUILD_DIR)/%.o: $(KERNEL_DIR)/%.c | $(BUILD_DIR)
+obj/%.o: %.c
-	$(CC) $(CFLAGS) -c $< -o $@
+	@mkdir -p $(dir $@)
+	$(CC) -c $< -o $@ $(CFLAGS)
 
-$(BUILD_DIR)/boot.elf: $(BUILD_DIR)/boot.o $(BOOT_DIR)/boot.ld
+obj/%.o: %.s
-	$(LD) -T $(BOOT_DIR)/boot.ld -o $@ $(BUILD_DIR)/boot.o
+	@mkdir -p $(dir $@)
+	$(CC) -c $< -o $@ $(CFLAGS)
 
-$(BOOT_BIN): $(BUILD_DIR)/boot.elf
+run: $(OSNAME).iso
-	$(OBJCOPY) -O binary $< $@
+	qemu-system-i386 -cdrom $(OSNAME).iso
-
-KERNEL_OBJS := $(BUILD_DIR)/prekernel.o $(BUILD_DIR)/kmain.o
-
-$(BUILD_DIR)/kernel.elf: $(KERNEL_OBJS) $(KERNEL_DIR)/kernel.ld
-	$(LD) -T $(KERNEL_DIR)/kernel.ld -o $@ $(KERNEL_OBJS)
-
-$(KERNEL_BIN): $(BUILD_DIR)/kernel.elf
-	$(OBJCOPY) -O binary $< $@
-
-$(BUILD_DIR):
-	mkdir -p $(BUILD_DIR)
-
-$(IMAGE): $(BOOT_BIN) $(KERNEL_BIN)
-	dd if=$(BOOT_BIN) of=$@ bs=512 count=1
-	dd if=$(KERNEL_BIN) of=$@ bs=512 seek=1
-	truncate -s 1440k $@
-
-run: $(IMAGE)
-	qemu-system-i386 -drive format=raw,file=$(IMAGE)
 
 clean:
-	rm -rf $(BUILD_DIR) $(IMAGE)
+	@echo "Cleaning up build artifacts..."
+	rm -rf $(OSNAME).iso $(OSNAME).bin obj isodir