Loaded program cannot do stuff. Answer=syscalls?

src/kernel/kmain.c

@@ -78,14 +78,14 @@ void kmain(multiboot2_info *mb_info)
 		
 		if (mmap->addr != 0)
 		{
-			
+			/*
 			serial_printf(3, "base addr=0x%x%x, length=0x%x%x, type=%u",
 				(uint32_t) (mmap->addr >> 32),
 				(uint32_t) (mmap->addr & 0xFFFFFFFF),
 				(uint32_t) (mmap->len >> 32),
 				(uint32_t) (mmap->len & 0xFFFFFFFF),
 				mmap->type);
-			
+			*/
 		}
 
 		mmap = (struct multiboot_mmap_entry*) ((uint8_t*)mmap + mmap_tag->entry_size);
@@ -128,6 +128,9 @@ void kmain(multiboot2_info *mb_info)
 	printf("LOADED!\n");
     }
 
+    void (*program_entry)() = (void (*)())binary_file;
+    program_entry();
+
     timer_install();
     keyboard_install();
     printf("[kernel] spawning shell...\n"); 

src/programs/hello.c

@@ -1,6 +1,8 @@
 #include "../libc/stdio.h"
+#include "../drivers/serial.h"
 
 void main()
 {
-	printf("Hello, world, from a PROGRAM!\n");
+	serial_printf(3, "Hello, world, from a PROGRAM!\n");
+	return;
 }