[driver] Allow boot text to be disabled

Suggested-by: Tal Aloni <tal.aloni.il@gmail.com>
Signed-off-by: Michael Brown <mbrown@fensystems.co.uk>

src/driver/boottext.c

@@ -62,6 +62,9 @@ VOID NTAPI InbvSolidColorFill ( IN ULONG Left, IN ULONG Top, IN ULONG Width,
 				IN ULONG Height, IN ULONG Color );
 VOID NTAPI InbvSetProgressBarSubset ( IN ULONG Floor, IN ULONG Ceiling );
 
+/** Boot text is enabled */
+BOOLEAN boottext_enabled = TRUE;
+
 /**
  * Print text to boot screen
  *
@@ -81,6 +84,10 @@ VOID BootPrint ( const char *fmt, ... ) {
 	/* Log to debugger, if attached */
 	DbgPrint ( "%s", buf );
 
+	/* Do nothing more unless boot text is enabled */
+	if ( ! boottext_enabled )
+		return;
+
 	/* Configure display */
 	if ( ! InbvCheckDisplayOwnership() )
 		InbvAcquireDisplayOwnership();

src/driver/boottext.h

@@ -19,6 +19,8 @@
  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  */
 
+extern BOOLEAN boottext_enabled;
+
 extern VOID BootPrint ( const char *fmt, ... );
 
 #endif /* _BOOTTEXT_H */