Truly enable virtual memory.

Map is still identity-mapped. I think we need to sort and/or clean up
the map before using a higher half address. In-kernel vga output not
working yet, but do_the_set_registers() is getting called.

src/boot/utility.h

@@ -18,3 +18,17 @@ const CHAR16 *util_error_message(EFI_STATUS status);
 		while (1) __asm__("hlt"); \
 	}
 
+#define CHECK_EFI_STATUS_OR_ASSERT(s, d)   \
+	if (EFI_ERROR((s))) { \
+		__asm__ __volatile__ ( \
+			"movq %0, %%r8;" \
+			"movq %1, %%r9;" \
+			"movq %2, %%r10;" \
+			"movq $0, %%rdx;" \
+			"divq %%rdx;" \
+			: \
+			:"r"((uint64_t)s), "r"((uint64_t)d), "r"((uint64_t)__LINE__) \
+			:"rax", "rdx", "r8", "r9", "r10" \
+			); \
+	}
+