Refactoring assembly entry point

kernel/cpu/main.asm

@@ -0,0 +1,27 @@
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;             vulcanOS Kernel           ;
+; Developed by Marco 'icebit' Cetica    ;
+;              (c) 2019-2021            ;
+;        Released under GPLv3           ;
+;   https://github.com/ice-bit/vulcanos ;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+GLOBAL kernel_loader
+EXTERN kernel_main
+[BITS 32] ; Ensure we are in protected mode
+
+section .text
+kernel_loader:
+    mov esp, kernel_stack + KERNEL_STACK_SZ ; Define stack pointer
+    push eax ; Set multiboot header register
+    call kernel_main ; Call kernel's main function
+.loop:
+    jmp .loop ; If the kernel returns, go into an endless loop
+              ; This will prevent the CPU to execure any non-kernel 
+              ; instructions.
+
+KERNEL_STACK_SZ equ 4096 ; Stack size(4KiB)
+
+section .bss
+align 4
+kernel_stack:
+    resb KERNEL_STACK_SZ ; Reserver 4KiB for kernel's stack