First pass for the following:

* adding sample function call
* adding 4KB of stack space

loader.asm

@@ -5,6 +5,27 @@ MAGIC_NUMBER 	equ 0x1BADB002
 FLAGS 			equ 0x0
 CHECKSUM 		equ -MAGIC_NUMBER
 
+; example stuff 
+A	equ 3
+B	equ 2
+C	equ 1
+
+; size in bytes
+KERNEL_STACK_SIZE	equ 4096
+
+; external labels(cdecl) calling convention
+extern sum
+
+section .bss
+align 4		; aligning to bytes for x86(32-bit) reasons
+; because this is the first thing we actually do (virual)address 0x00000000 will 
+; contain 4KB of memory for our stack
+kernel_stack:
+	resb KERNEL_STACK_SIZE	; reserver bytes instruction
+	; point to what will be bottom of stack
+	; which will grow down towards (virtual)address 0x00000000
+	mov esp, kernel_stack + KERNEL_STACK_SIZE	
+
 section .text
 ; align all instructions to 4 byte boundary by the x86 instruction set law
 align 4
@@ -15,6 +36,11 @@ align 4
 
 loader:
 	mov eax, 0X1234ABCD
+	; call our external function
+	push dword C
+	push dword B
+	push dword A
+	call sum
 
 .loop:
 	jmp .loop