[feat] Simple output

boot.c

@@ -1,9 +1,17 @@
 #include <efi.h>
 #include <efilib.h>
 
-EFI_STATUS EFIAPI efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable) {
-    InitializeLib(ImageHandle, SystemTable);
-    Print(L"Hello, world!\n");
-    while (1);
+EFI_STATUS EFIAPI efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *ST) {
+    InitializeLib(ImageHandle, ST);
+
+    // 不能直接ST->ConOut之类的，会GP，不知道为什么
+    // uefi_call_wrapper可以解决，而且比较安全（不过就是宏）
+    // 看着挺长，反正就在boot这里用到UEFI Out，后面不用，也就算了
+    uefi_call_wrapper(ST->ConOut->ClearScreen, 1, ST->ConOut);
+    uefi_call_wrapper(ST->ConOut->SetCursorPosition, 3, ST->ConOut, 0, 1);
+    uefi_call_wrapper(ST->ConOut->OutputString, 2, ST->ConOut, L"Welcome to SYLVA OS!\n");
+    uefi_call_wrapper(ST->ConOut->SetCursorPosition, 3, ST->ConOut, 0, 2);
+    uefi_call_wrapper(ST->ConOut->OutputString, 2, ST->ConOut, L"* The system has booted successfully.\n");
+    while (1); // 否则会直接跳到QEMU Setup
     return EFI_SUCCESS;
 }