src/config/cloud/general.h - ipxe - Git at Google

 /* Enable IPv6 and HTTPS */
 #define NET_PROTO_IPV6
 #define DOWNLOAD_PROTO_HTTPS

 /* Allow retrieval of metadata (such as an iPXE boot script) from
  * Google Compute Engine metadata server.
  */
 #define HTTP_HACK_GCE
	/* Enable IPv6 and HTTPS */
	#define NET_PROTO_IPV6
	#define DOWNLOAD_PROTO_HTTPS

	/* Allow retrieval of metadata (such as an iPXE boot script) from
	* Google Compute Engine metadata server.
	*/
	#define HTTP_HACK_GCE