virtio_blk_outhdr
struct virtio_blk_outhdr *header = (struct virtio_blk_outhdr*)info->bufferAddr;
uint8* ack = (uint8*)info->bufferAddr + sizeof(struct virtio_blk_outhdr);
entries[0].size = sizeof(struct virtio_blk_outhdr);
+ sizeof(struct virtio_blk_outhdr);