struct tag {

         struct tag_header hdr;

         union {

                   struct tag_core                  core;

                   struct tag_mem32  mem;

                   struct tag_videotext        videotext;

                   struct tag_ramdisk  ramdisk;

                   struct tag_initrd       initrd;

                   struct tag_serialnr   serialnr;

                   struct tag_revision  revision;

                   struct tag_videolfb  videolfb;

                   struct tag_cmdline  cmdline;

                   /*

                    * Acorn specific

                    */

                   struct tag_acorn      acorn;

                   /*

                    * DC21285 specific

                    */

                   struct tag_memclk  memclk;

         } u;

};