debug2.patch

diff --git a/cores/rp2040/debug_internal.h b/cores/rp2040/debug_internal.h
index 81026fb..e8b206f 100644
--- a/cores/rp2040/debug_internal.h
+++ b/cores/rp2040/debug_internal.h
@@ -20,6 +20,9 @@
 
 #pragma once
 
+typedef int SerialPrintf(const char *format, ...) __attribute__ ((format (printf, 1, 2)));
+extern SerialPrintf *DEBUG_RP2040_PRINTF;
+
 #if !defined(DEBUG_RP2040_PORT)
 #define DEBUGV(...) do { } while(0)
 #define DEBUGCORE(...) do { } while(0)
diff --git a/cores/rp2040/main.cpp b/cores/rp2040/main.cpp
index fb1ed21..a8e98f9 100644
--- a/cores/rp2040/main.cpp
+++ b/cores/rp2040/main.cpp
@@ -24,6 +24,9 @@
 #include <pico/multicore.h>
 #include <reent.h>
 
+static int dummyDebugPrintf(const char *, ...) { return -1; }
+SerialPrintf *DEBUG_RP2040_PRINTF = dummyDebugPrintf;
+
 RP2040 rp2040;
 extern "C" {
     volatile bool __otherCoreIdled = false;