...

grub.cfg

@@ -1,4 +1,3 @@
 menuentry "nub-os" {
     multiboot /boot/kernel.bin
-    boot
 }

makefile

@@ -17,17 +17,14 @@ build-dir:
 	cp .build/kernel.bin .build/iso/boot/
 	grub-mkrescue -o .build/nub-os.iso .build/iso/
 
-.build/kernel.bin: build-dir .build/entry.o .build/kernel.o .build/mem.o .build/print.o
-	$(LD) -Ttext 0x100000 -o .build/kernel.bin .build/entry.o .build/kernel.o .build/mem.o .build/print.o
+.build/kernel.bin: build-dir .build/boot.o .build/kernel.o .build/print.o
+	$(LD) -Ttext 0x100000 -o .build/kernel.bin .build/boot.o .build/kernel.o .build/print.o
 
 .build/kernel.o: build-dir src/kernel.c
 	$(CC) $(CFLAGS) -c -o .build/kernel.o src/kernel.c
 
-.build/mem.o: build-dir src/mem.c
-	$(CC) $(CFLAGS) -c -o .build/mem.o src/mem.c
-
 .build/print.o: build-dir src/print.c
 	$(CC) $(CFLAGS) -c -o .build/print.o src/print.c
 
-.build/entry.o: build-dir src/entry.asm
-	nasm -f elf -o .build/entry.o src/entry.asm
+.build/boot.o: build-dir src/boot.asm
+	nasm -f elf32 -o .build/boot.o src/boot.asm

src/boot.asm

@@ -0,0 +1,27 @@
+extern kernel_main
+
+%define MAGIC       0x1BADB002
+%define FLAGS       0x0
+%define CHECKSUM    -(MAGIC + FLAGS)
+
+section .multiboot
+align 4
+    dd MAGIC
+    dd FLAGS
+    dd CHECKSUM
+
+section .bss
+align 16
+stack_bottom:
+resb 16384
+stack_top:
+
+section .text
+global _start
+_start:
+    mov esp, stack_top
+    call kernel_main
+    cli
+hang:
+    hlt
+    jmp hang

src/entry.asm

@@ -1,21 +0,0 @@
-extern kernel_init
-
-section .multiboot
-align 4
-    dd 0x1BADB002          ; multiboot magic number
-    dd 0x0                 ; flags
-    dd -(0x1BADB002+0x0)   ; checksum
-
-section .text
-global _start
-_start:
-    cli
-    mov esp, stack_top
-    call kernel_init
-.hang:
-    hlt
-    jmp .hang
-
-section .bss
-resb 8192
-stack_top:

src/kernel.c

@@ -1,6 +1,6 @@
 #include "print.h"
 
-void kernel_init(void)
+void kernel_main(void)
 {
     print("Starting nub-os\n");
 }

src/mem.c

@@ -1,26 +0,0 @@
-#include "mem.h"
-
-void* memcpy(void* dest, const void* src, long n)
-{
-    char* d = dest;
-    const char* s = src;
-    for (long i = 0; i < n; i++)
-        d[i] = s[i];
-    return dest;
-}
-
-void* memset(void* dest, int val, long n)
-{
-    char* d = dest;
-    for (long i = 0; i < n; i++)
-        d[i] = val;
-    return dest;
-}
-
-long strlen(const char* str)
-{
-    long len = 0;
-    while (str[len])
-        len++;
-    return len;
-}

src/mem.h

@@ -1,3 +0,0 @@
-void* memcpy(void* dest, const void* src, long n);
-void* memset(void* dest, int val, long n);
-long strlen(const char* str);