Add dummy "initrd" image format, just so that images can be marked as

initrds.

src/arch/i386/image/initrd.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/**
+ * @file
+ *
+ * Linux initrd image format
+ *
+ * This file does nothing except provide a way to mark images as being
+ * initrds.  The actual processing is done in the Linux kernel image
+ * code; this file exists so that we can include the "initrd" command
+ * without necessarily dragging in the Linux image format.
+ *
+ */
+
+#include <initrd.h>
+#include <gpxe/image.h>
+
+/** Linux initrd image type */
+struct image_type initrd_image_type __image_type ( PROBE_NORMAL ) = {
+	.name = "initrd",
+};

src/arch/i386/include/initrd.h

@@ -0,0 +1,14 @@
+#ifndef _INITRD_H
+#define _INITRD_H
+
+/**
+ * @file
+ *
+ * Linux initrd image format
+ *
+ */
+
+#include <gpxe/image.h>
+extern struct image_type initrdimage_image_type __image_type ( PROBE_NORMAL );
+
+#endif /* _INITRD_H */