From c08fcb3813f6303bbdfa4756c2261918a09c1191 Mon Sep 17 00:00:00 2001
From: Fredrik Orderud <fredrik.orderud@gehealthcare.com>
Date: Mon, 23 Sep 2024 14:52:29 +0200
Subject: [PATCH] Fix broken usb_init_serialnumber() linking after C++ compiler
 switch.

---
 teensy4/usb_desc.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/teensy4/usb_desc.cpp b/teensy4/usb_desc.cpp
index c97c9773..69213d37 100644
--- a/teensy4/usb_desc.cpp
+++ b/teensy4/usb_desc.cpp
@@ -2751,7 +2751,7 @@ PROGMEM const struct usb_string_descriptor_struct usb_string_mtp = {
 };
 #endif
 
-void usb_init_serialnumber(void)
+extern "C" void usb_init_serialnumber(void)
 {
 	char buf[11];
 	uint32_t i, num;