fixed regression

arch/x86/kernel/entry64.asm

@@ -230,7 +230,7 @@ cpu_init:
 
 ALIGN 4
 stublet:
-    mov esp, startup_stack
+    mov esp, startup_stack-4
 ; save pointer to the multiboot structure
     push ebx
 ; initialize cpu features

mm/memory.c

@@ -109,7 +109,6 @@ int mmu_init(void)
 
 		while (mmap < mmap_end) {
 			if (mmap->type == MULTIBOOT_MEMORY_AVAILABLE) {
-				/
 				// set the available memory as "unused"
 				addr = mmap->addr;
 				end_addr = addr + mmap->len;