i2o_header
#define I2O_COMMAND_SIZE (I2O_MESSAGE_SIZE - sizeof(struct i2o_header))
struct i2o_header header;
size = sizeof(struct i2o_header) + data_size;
static struct i2o_header header = I2O_HEADER_TEMPLATE;
memcpy_toio(&message->header, &header, sizeof(struct i2o_header));