page_descriptor
key.descriptor = (struct page_descriptor) {
BUILD_BUG_ON(sizeof(struct page_descriptor) != sizeof(u64));
struct page_descriptor descriptor;
req->page_descriptor[i].low = cpu_to_le32(lower_32_bits(phys));
req->page_descriptor[i].high = cpu_to_le32(upper_32_bits(phys));
struct sli4_dmaaddr page_descriptor[];