Index: VirtualBox-6.1.28/include/iprt/stdarg.h
===================================================================
--- VirtualBox-6.1.28.orig/include/iprt/stdarg.h
+++ VirtualBox-6.1.28/include/iprt/stdarg.h
@@ -51,7 +51,12 @@
 #   include <stdarg.h>
 #  endif
 # else
-#  include <stdarg.h>
+#  include <linux/version.h>
+#  if LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
+#   include <stdarg.h>
+#  else
+#   include <linux/stdarg.h>
+#  endif
 # endif
 #endif