I forgot to put backends/vhost-user-blk-server.o as dependency for
qemu-vu target in Makefile,
qemu-img$(EXESUF): qemu-img.o $(authz-obj-y) $(block-obj-y)
$(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)
qemu-nbd$(EXESUF): qemu-nbd.o $(authz-obj-y) $(block-obj-y)
$(crypto-obj-y) $(io-ob
vhost-user-blk could have played as vhost-user backend but it only supports raw
file and don't support VIRTIO_BLK_T_DISCARD and VIRTIO_BLK_T_WRITE_ZEROES
operations on raw file (ioctl(fd, BLKDISCARD) is only valid for real
block device).
In the future Kevin's qemu-storage-daemon will be used to re
