[feat] Memory manager

kernel/serial.cpp

@@ -35,6 +35,18 @@ void serial_write(const char *str) {
     }
 }
 
+void serial_write_hex(UINTN val) {
+    char buf[19];
+    buf[0] = '0'; buf[1] = 'x';
+    for (int i = 17; i >= 2; i--) {
+        UINTN digit = val & 0xF;
+        buf[i] = digit < 10 ? '0' + digit : 'A' + digit - 10;
+        val >>= 4;
+    }
+    buf[18] = '\0';
+    serial_write(buf);
+}
+
 char serial_read_char() {
     // 后面可能用的上，比如远程调试？
     if (!g_serial.SerialIo) return 0;