feat: some clean up and validation of multiboot header

kernel/kernel.c

@@ -49,7 +49,8 @@ void init_block_devices() {
     fat_register_block_driver();
 }
 
-void noreturn kmain(multiboot_info_t *multiboot_info) {
+void noreturn kmain(multiboot_info_t *multiboot_info, uint32_t mb_name) {
+    // early init
     isr_install();
     vga_clear_screen();
     vga_clear_screen(' ', VGA_WHITE | (VGA_GRAY << VGA_SHIFT_BG));
@@ -57,25 +58,42 @@ void noreturn kmain(multiboot_info_t *multiboot_info) {
     serial_init();
     kprint_register(serial_kprint);
 
+    // parse multiboot
+    if (mb_name != MULTIBOOT_BOOTLOADER_MAGIC) {
+        k_panics("Not booted by multiboot\n");
+    }
+
     store_bootloader_info(multiboot_info);
+
+    // initialize memory management
     init_mmap(multiboot_info);
 
+    // initialize kprint functionality
     kprint_init();
 
+    // identify cpu
     cpuidx_print_info();
 
-    // init done, enable interrupts
+    // enable interrupts
     __asm__ __volatile__("sti");
+    // start the timer
     init_timer(1000);
+    // initialize devices
     init_keyboard();
     init_pci_system();
+
+    // register block device drivers
     init_block_devices();
 
     printf("Booted successfully v%d.%d.%d\n", version_major, version_minor, version_patch);
 
+    // initialize tasking
     task_init();
     kprint_start_task();
     block_dev_start_task();
+#ifdef K_SHELL
     task_spawn(main_loop, NULL);
+#endif
+    // switch to tasking
     syscall_start_scheduler();
 }