diff --git a/README.rst b/README.rst
index 480600b0..72d586c6 100644
--- a/README.rst
+++ b/README.rst
@@ -305,7 +305,7 @@ by MIT license.
 The library functions (all code in lib/ directory and include/ublksrv.h)
 are covered by dual licensed LGPL and MIT, see COPYING.LGPL and LICENSE.
 
-qcow2 target code is covered by GPL-2.0, see COPYING.
+qcow2 and nbd target code is covered by GPL-2.0, see COPYING.
 
 All other source code are covered by dual licensed GPL and MIT, see
 COPYING and LICENSE.
diff --git a/include/ublk_cmd.h b/include/ublk_cmd.h
index a5da4d20..c0c8f44a 100644
--- a/include/ublk_cmd.h
+++ b/include/ublk_cmd.h
@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* SPDX-License-Identifier: (GPL-2.0 WITH Linux-syscall-note) or MIT */
 #ifndef USER_BLK_DRV_CMD_INC_H
 #define USER_BLK_DRV_CMD_INC_H
 
diff --git a/include/ublksrv_tgt_endian.h b/include/ublksrv_tgt_endian.h
index 03d98e6e..df061726 100644
--- a/include/ublksrv_tgt_endian.h
+++ b/include/ublksrv_tgt_endian.h
@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0
+// SPDX-License-Identifier: MIT or GPL-2.0-only
 #ifndef UBLK_TGT_ENDIAN_H
 #define UBLK_TGT_ENDIAN_H
 
@@ -6,136 +6,23 @@
 
 /* ublksrv target code private header, not for libublksrv user */
 
-static inline uint16_t bswap16(uint16_t x)
-{
-    return bswap_16(x);
-}
-static inline uint32_t bswap32(uint32_t x)
-{
-    return bswap_32(x);
-}
-static inline uint64_t bswap64(uint64_t x)
-{
-    return bswap_64(x);
-}
-
-static inline void bswap16s(uint16_t *s)
-{
-    *s = bswap16(*s);
-}
-
-static inline void bswap32s(uint32_t *s)
-{
-    *s = bswap32(*s);
-}
-
-static inline void bswap64s(uint64_t *s)
-{
-    *s = bswap64(*s);
-}
-
-#ifndef glue
-#define xglue(x, y) x ## y
-#define glue(x, y) xglue(x, y)
-#endif
-
-#if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
-#define be_bswap(v, size) (v)
-#define le_bswap(v, size) glue(bswap, size)(v)
-#define be_bswaps(v, size)
-#define le_bswaps(p, size) do { *p = glue(bswap, size)(*p); } while(0)
-#else
-#define le_bswap(v, size) (v)
-#define be_bswap(v, size) glue(bswap, size)(v)
-#define le_bswaps(v, size)
-#define be_bswaps(p, size) do { *p = glue(bswap, size)(*p); } while(0)
-#endif
-
-/**
- * Endianness conversion functions between host cpu and specified endianness.
- * (We list the complete set of prototypes produced by the macros below
- * to assist people who search the headers to find their definitions.)
- *
- * uint16_t le16_to_cpu(uint16_t v);
- * uint32_t le32_to_cpu(uint32_t v);
- * uint64_t le64_to_cpu(uint64_t v);
- * uint16_t be16_to_cpu(uint16_t v);
- * uint32_t be32_to_cpu(uint32_t v);
- * uint64_t be64_to_cpu(uint64_t v);
- *
- * Convert the value @v from the specified format to the native
- * endianness of the host CPU by byteswapping if necessary, and
- * return the converted value.
- *
- * uint16_t cpu_to_le16(uint16_t v);
- * uint32_t cpu_to_le32(uint32_t v);
- * uint64_t cpu_to_le64(uint64_t v);
- * uint16_t cpu_to_be16(uint16_t v);
- * uint32_t cpu_to_be32(uint32_t v);
- * uint64_t cpu_to_be64(uint64_t v);
- *
- * Convert the value @v from the native endianness of the host CPU to
- * the specified format by byteswapping if necessary, and return
- * the converted value.
- *
- * void le16_to_cpus(uint16_t *v);
- * void le32_to_cpus(uint32_t *v);
- * void le64_to_cpus(uint64_t *v);
- * void be16_to_cpus(uint16_t *v);
- * void be32_to_cpus(uint32_t *v);
- * void be64_to_cpus(uint64_t *v);
- *
- * Do an in-place conversion of the value pointed to by @v from the
- * specified format to the native endianness of the host CPU.
- *
- * void cpu_to_le16s(uint16_t *v);
- * void cpu_to_le32s(uint32_t *v);
- * void cpu_to_le64s(uint64_t *v);
- * void cpu_to_be16s(uint16_t *v);
- * void cpu_to_be32s(uint32_t *v);
- * void cpu_to_be64s(uint64_t *v);
- *
- * Do an in-place conversion of the value pointed to by @v from the
- * native endianness of the host CPU to the specified format.
- *
- * Both X_to_cpu() and cpu_to_X() perform the same operation; you
- * should use whichever one is better documenting of the function your
- * code is performing.
- *
- * Do not use these functions for conversion of values which are in guest
- * memory, since the data may not be sufficiently aligned for the host CPU's
- * load and store instructions. Instead you should use the ld*_p() and
- * st*_p() functions, which perform loads and stores of data of any
- * required size and endianness and handle possible misalignment.
- */
-
-#define CPU_CONVERT(endian, size, type)\
+#define HOST_CONVERT(endian, size, type)\
 static inline type endian ## size ## _to_cpu(type v)\
 {\
-    return glue(endian, _bswap)(v, size);\
+	return endian ## size ## toh(v); \
 }\
 \
 static inline type cpu_to_ ## endian ## size(type v)\
 {\
-    return glue(endian, _bswap)(v, size);\
+	return hto ## endian ## size(v); \
 }\
-\
-static inline void endian ## size ## _to_cpus(type *p)\
-{\
-    glue(endian, _bswaps)(p, size);\
-}\
-\
-static inline void cpu_to_ ## endian ## size ## s(type *p)\
-{\
-    glue(endian, _bswaps)(p, size);\
-}
 
-CPU_CONVERT(be, 16, uint16_t)
-CPU_CONVERT(be, 32, uint32_t)
-CPU_CONVERT(be, 64, uint64_t)
+HOST_CONVERT(be, 16, uint16_t)
+HOST_CONVERT(be, 32, uint32_t)
+HOST_CONVERT(be, 64, uint64_t)
 
-CPU_CONVERT(le, 16, uint16_t)
-CPU_CONVERT(le, 32, uint32_t)
-CPU_CONVERT(le, 64, uint64_t)
+HOST_CONVERT(le, 16, uint16_t)
+HOST_CONVERT(le, 32, uint32_t)
+HOST_CONVERT(le, 64, uint64_t)
 
 #endif
diff --git a/tests/common/nbd_common b/tests/common/nbd_common
index ab4eda5e..aabccc9d 100755
--- a/tests/common/nbd_common
+++ b/tests/common/nbd_common
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 export NBDSRV=127.0.0.1
 export NBD_SIZE=2G
diff --git a/tests/common/qcow2_common b/tests/common/qcow2_common
index 9c4b3405..a0cc1469 100755
--- a/tests/common/qcow2_common
+++ b/tests/common/qcow2_common
@@ -1,5 +1,5 @@
-# SPDX-License-Identifier: GPL-2.0
 #!/bin/bash
+# SPDX-License-Identifier: MIT or GPL-2.0-only
 
 export QCOW2_IMG_SZ=2G
 
diff --git a/tests/debug/test_dev b/tests/debug/test_dev
index b1ed84d1..b5c0ba66 100755
--- a/tests/debug/test_dev
+++ b/tests/debug/test_dev
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0-only
 #
 #usage:
 #	export UBLK_DBG_DEV=/dev/vdc; make test T=debug/test_dev
diff --git a/tests/nbd/001 b/tests/nbd/001
index 6768f6a1..c1e6a474 100755
--- a/tests/nbd/001
+++ b/tests/nbd/001
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/nbd/002 b/tests/nbd/002
index aab42991..3bf2943a 100755
--- a/tests/nbd/002
+++ b/tests/nbd/002
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/nbd/003 b/tests/nbd/003
index 338187b0..f35412ac 100755
--- a/tests/nbd/003
+++ b/tests/nbd/003
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/nbd/021 b/tests/nbd/021
index 2921bf90..af49106e 100755
--- a/tests/nbd/021
+++ b/tests/nbd/021
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/nbd/022 b/tests/nbd/022
index 8ddd038b..72d88ee7 100755
--- a/tests/nbd/022
+++ b/tests/nbd/022
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/nbd/023 b/tests/nbd/023
index e37a0108..eef0bd8c 100755
--- a/tests/nbd/023
+++ b/tests/nbd/023
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/nbd/041 b/tests/nbd/041
index 5c49536a..70c56538 100755
--- a/tests/nbd/041
+++ b/tests/nbd/041
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/nbd/042 b/tests/nbd/042
index b5f673bb..c3d1c326 100755
--- a/tests/nbd/042
+++ b/tests/nbd/042
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/nbd/043 b/tests/nbd/043
index e463774e..46085546 100755
--- a/tests/nbd/043
+++ b/tests/nbd/043
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/nbd_common
diff --git a/tests/qcow2/001 b/tests/qcow2/001
index 7367dc3a..4cb16785 100755
--- a/tests/qcow2/001
+++ b/tests/qcow2/001
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/qcow2_common
diff --git a/tests/qcow2/002 b/tests/qcow2/002
index 0e67a478..789702d9 100755
--- a/tests/qcow2/002
+++ b/tests/qcow2/002
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/qcow2_common
diff --git a/tests/qcow2/021 b/tests/qcow2/021
index d820fcf9..a61daa2d 100755
--- a/tests/qcow2/021
+++ b/tests/qcow2/021
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/qcow2_common
diff --git a/tests/qcow2/022 b/tests/qcow2/022
index 972a9851..16e3c404 100755
--- a/tests/qcow2/022
+++ b/tests/qcow2/022
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/qcow2_common
diff --git a/tests/qcow2/040 b/tests/qcow2/040
index b7c879dc..81e0ca44 100755
--- a/tests/qcow2/040
+++ b/tests/qcow2/040
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/qcow2_common
diff --git a/tests/qcow2/041 b/tests/qcow2/041
index 3edc08a9..ec8a2aeb 100755
--- a/tests/qcow2/041
+++ b/tests/qcow2/041
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0
 
 . common/fio_common
 . common/qcow2_common
diff --git a/tests/qcow2/big_size_fs_io b/tests/qcow2/big_size_fs_io
index 7c736c02..aa344719 100755
--- a/tests/qcow2/big_size_fs_io
+++ b/tests/qcow2/big_size_fs_io
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0-only
 
 . common/fio_common
 . common/qcow2_common
diff --git a/tests/qcow2/big_size_io b/tests/qcow2/big_size_io
index 0fca12ac..e30fbe65 100755
--- a/tests/qcow2/big_size_io
+++ b/tests/qcow2/big_size_io
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0-only
 
 . common/fio_common
 . common/qcow2_common
diff --git a/utils/genver.sh b/utils/genver.sh
index 50479df3..acdf5351 100755
--- a/utils/genver.sh
+++ b/utils/genver.sh
@@ -1,5 +1,5 @@
 #!/bin/sh
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0-only
 
 GITDESC=$(git describe --dirty|sed -e 's/^v//' 2>/dev/null)
 
diff --git a/utils/nop.c b/utils/nop.c
deleted file mode 100644
index 55156831..00000000
--- a/utils/nop.c
+++ /dev/null
@@ -1,65 +0,0 @@
-/* SPDX-License-Identifier: MIT */
-#include <errno.h>
-#include <stdio.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <string.h>
-#include <fcntl.h>
-#include <liburing.h>
-
-/* gcc -g -o nop nop.c -luring */
-
-/* test nop over uring and see io_uring is working */
-static int test_nop()
-{
-	struct io_uring _ring;
-	struct io_uring *ring = &_ring;
-	struct io_uring_params p = { };
-	int ret, i;
-	struct io_uring_cqe *cqe;
-	struct io_uring_sqe *sqe;
-
-	p.flags = IORING_SETUP_SQE128;
-	ret = io_uring_queue_init_params(64, ring, &p);
-	if (ret < 0) {
-		fprintf(stderr, "ring can't be setup %d\n", ret);
-		goto err;
-	}
-
-	ret = -EINVAL;
-	sqe = io_uring_get_sqe(ring);
-	if (!sqe) {
-		fprintf(stderr, "get sqe failed ret %d\n", ret);
-		return ret;
-	}
-
-	io_uring_prep_nop(sqe);
-	sqe->user_data = 1;
-	ret = io_uring_submit(ring);
-	if (ret <= 0) {
-		fprintf(stderr, "sqe submit failed: %d\n", ret);
-		goto err;
-	}
-
-	ret = io_uring_wait_cqe(ring, &cqe);
-	if (ret < 0) {
-		fprintf(stderr, "wait completion %d\n", ret);
-		goto err;
-	}
-	if (!cqe->user_data) {
-		fprintf(stderr, "Unexpected 0 user_data\n");
-		goto err;
-	}
-	io_uring_cqe_seen(ring, cqe);
-	fprintf(stdout, "nop over uring run successfully\n");
-err:
-	io_uring_queue_exit(ring);
-	return ret;
-}
-
-int main(int argc, char *argv[])
-{
-	test_nop();
-
-	return 0;
-}
diff --git a/utils/ublk_chown_docker.sh b/utils/ublk_chown_docker.sh
index a0e7841c..68a2fd7a 100755
--- a/utils/ublk_chown_docker.sh
+++ b/utils/ublk_chown_docker.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# SPDX-License-Identifier: GPL-2.0
+# SPDX-License-Identifier: MIT or GPL-2.0-only
 
 ublk_docker_add()
 {