Do some more formatted logging

kernel/src/main.cpp

@@ -30,6 +30,8 @@ extern "C" [[noreturn]] void _start()
 
     u64 physical = MemoryManager::alloc_physical_page().release_value();
 
+    Serial::printf("Allocated physical frame %#lx\n", physical);
+
     auto rc = MMU::map(address, physical, MMU::ReadWrite);
     bool success = !rc.has_error();
 
@@ -80,6 +82,8 @@ extern "C" [[noreturn]] void _start()
         CPU::efficient_halt();
     }
 
+    Serial::printf("Unmapped page, was pointing to %#lx\n", urc.value());
+
     if (urc.release_value() != physical)
     {
         Serial::println("unmap returned a different address than the one we mapped");