Set up environment, wrote loader and Makefile

Makefile

@@ -0,0 +1,39 @@
+OBJECTS = loader.o kmain.o
+
+CC = gcc
+CCFLAGS = -m32 -nostdlib -nostdinc -fno-builtin -fno-stack-protector \
+		  -nostartfiles -nodefaultlibs -Wall -Wextra -Werror -c
+LDFLAGS = -T link.ld -melf_i386
+
+AS = nasm
+ASFLAGS = -f elf32
+
+all: kernel.elf
+
+kernel.elf: $(OBJECTS)
+	ld $(LDFLAGS) $(OBJECTS) -o kernel.elf
+
+os.iso: kernel.elf
+	cp kernel.elf iso/boot/kernel.elf
+	genisoimage -R 					         \
+				-b boot/grub/stage2_eltorito \
+				-no-emul-boot 				 \
+				-boot-load-size 4 			 \
+				-A os 						 \
+				-input-charset utf8 		 \
+				-quiet 						 \
+				-boot-info-table 			 \
+				-o os.iso 					 \
+				iso
+
+run: os.iso
+	bochs -f bochsrc.txt -q
+
+%.o: %.c
+	$(CC) $(CCFLAGS) $< -o $@
+
+%.o: %.s
+	$(AS) $(ASFLAGS) $< -o $@
+
+clean:
+	rm -rf *.o kernel.elf os.iso bochslog.txt iso/boot/kernel.elf

README.md

@@ -1 +1,7 @@
 # lucicOS
+
+Tools used:
+    * compiler - gcc
+    * assembler - nasm
+    * emulator - bochs
+    * GRUB legacy bootloader - stage2\_eltorito 

bochsrc.txt

@@ -0,0 +1,9 @@
+megs:            32
+display_library: sdl
+romimage:        file=/usr/share/bochs/BIOS-bochs-latest
+vgaromimage:     file=/usr/share/bochs/VGABIOS-lgpl-latest
+ata0-master:     type=cdrom, path=os.iso, status=inserted
+boot:            cdrom
+log:             bochslog.txt
+clock:           sync=realtime, time0=local
+cpu:             count=1, ips=1000000

iso/boot/grub/menu.lst

@@ -0,0 +1,5 @@
+default=0
+timeout=0
+
+title os
+kernel /boot/kernel.elf

kmain.c

@@ -0,0 +1,3 @@
+void kmain(void) {
+
+}

link.ld

@@ -0,0 +1,44 @@
+ENTRY(loader)
+
+SECTIONS {
+
+    /*
+     * The code should be loaded at an address greater or equal to 1MB because
+     * lower addresses are reserved to GRUB, BIOS and memory mapped I/O.
+     *
+     */
+
+    . = 0x00100000;
+
+    /*
+     * Align all sections from all files to a 4KB boundary.
+     *
+     */
+
+    .text ALIGN (0x1000) : {
+        *(.multiboot)
+        *(.text)
+    }
+
+    .rodata ALIGN (0x1000) : {
+        *(.rodata*)
+    }
+
+    .data ALIGN (0x1000) : {
+        *(.data)
+    }
+
+    /*
+     * Note:
+     *  COMMON section keeps data objects that are not yet allocated,
+     *  this is just a prelinking section, it will be transformed into bss
+     *  and data after linking.
+     *
+     */
+
+    .bss ALIGN (0x1000) : {
+        *(COMMON)
+        *(.bss)
+    }
+
+}

loader.s

@@ -0,0 +1,43 @@
+global loader
+
+; Entry point in the kernel.
+
+extern kmain
+
+; GRUB will load the kernel only if it compiles with the multiboot spec.
+; The header must contain a magic number, a flag (which can be set to 0x00)
+; and the checksum (checksum = - (flag + magic_number))
+
+MAGIC_NUMBER equ 0x1BADB002
+FLAGS        equ 0x00
+CHECKSUM     equ -(MAGIC_NUMBER + FLAGS)
+
+; Put the header in multiboot section so that it is placed in the first 8Kib
+; of the executable.
+
+section .multiboot
+    align 4
+
+    dd MAGIC_NUMBER
+    dd FLAGS
+    dd CHECKSUM
+
+; Create a kstack so that the entry point in the kernel can be called.
+
+KSTACK_SIZE equ 4096
+
+section .bss
+    align 4
+
+    kstack resb KSTACK_SIZE
+
+; Set the stack and call kmain.
+
+section .text
+
+loader:
+    mov esp, kstack + KSTACK_SIZE
+    call kmain
+
+.halt:
+    jmp .halt