ahci_sg
struct ahci_sg *ahci_sg = cmd_tbl + AHCI_CMD_TBL_HDR_SZ;
ahci_sg[si].addr = cpu_to_le32(addr & 0xffffffff);
ahci_sg[si].addr_hi = cpu_to_le32((addr >> 16) >> 16);
ahci_sg[si].flags_size = cpu_to_le32(sg_len - 1);