The prototype of DbgPrint() is incorrect, at the end of "inc/efidebug.h".

Consequently, when your program calls DbgPrint() via the DEBUG() macro,
it fails to set up the stack correctly (it does not pass the arguments
through the ellipsis (...) according to the EFIAPI calling convention).
However, va_start() inside DbgPrint() *assumes* that stack.

Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Nigel Croxon <nigel.croxon@hp.com>

gnu-efi-3.0/inc/efidebug.h

@@ -99,7 +99,7 @@ DbgAssert (
     CHAR8   *string
     );
 
-INTN
+INTN EFIAPI
 DbgPrint (
     INTN    mask,
     CHAR8   *format,

gnu-efi-3.0/lib/print.c

@@ -179,7 +179,7 @@ _PoolPrint (
     IN CHAR16   *Buffer
     );
 
-INTN
+INTN EFIAPI
 DbgPrint (
     IN INTN      mask,
     IN CHAR8     *fmt,