snd_trident_memblk_arg
trident->tlb.memhdr->block_extra_size = sizeof(struct snd_trident_memblk_arg);
#define firstpg(blk) (((struct snd_trident_memblk_arg *)snd_util_memblk_argptr(blk))->first_page)
#define lastpg(blk) (((struct snd_trident_memblk_arg *)snd_util_memblk_argptr(blk))->last_page)