diff --git a/boards/Kconfig b/boards/Kconfig
index fbab1e97d984e6..f56c2cab04ef9a 100644
--- a/boards/Kconfig
+++ b/boards/Kconfig
@@ -111,6 +111,15 @@ config QEMU_GDBSERVER_LISTEN_DEV
 	  as the `QEMU_EXTRA_FLAGS` environment variable. Refer to application
 	  development doc and/or QEMU invocation doc for more info.
 
+config QEMU_EXTRA_FLAGS
+	string "QEMU extra flags"
+	depends on QEMU_TARGET
+	default ""
+	help
+	  This option is to pass onto QEMU an extra list of parameters
+	  to setup devices, for example to allocate interface for Zephyr
+	  GDBstub over serial with `-serial tcp:127.0.0.1:5678,server`
+
 # There might not be any board options, hence the optional source
 osource "$(BOARD_DIR)/Kconfig"
 endmenu
diff --git a/cmake/emu/qemu.cmake b/cmake/emu/qemu.cmake
index a3a8a94515b537..6103fc1cefc15f 100644
--- a/cmake/emu/qemu.cmake
+++ b/cmake/emu/qemu.cmake
@@ -399,6 +399,13 @@ set(env_qemu $ENV{QEMU_EXTRA_FLAGS})
 separate_arguments(env_qemu)
 list(APPEND QEMU_EXTRA_FLAGS ${env_qemu})
 
+# Also append QEMU flags from config
+if(NOT CONFIG_QEMU_EXTRA_FLAGS STREQUAL "")
+  set(config_qemu_flags ${CONFIG_QEMU_EXTRA_FLAGS})
+  separate_arguments(config_qemu_flags)
+  list(APPEND QEMU_EXTRA_FLAGS "${config_qemu_flags}")
+endif()
+
 list(APPEND MORE_FLAGS_FOR_debugserver_qemu -S)
 
 if(NOT CONFIG_QEMU_GDBSERVER_LISTEN_DEV STREQUAL "")
diff --git a/doc/services/debugging/gdbstub.rst b/doc/services/debugging/gdbstub.rst
index 5b702d9569802f..50b830fb5b86a6 100644
--- a/doc/services/debugging/gdbstub.rst
+++ b/doc/services/debugging/gdbstub.rst
@@ -87,8 +87,9 @@ Using Serial Backend
 Example
 *******
 
-This is an example using ``samples/subsys/debug/gdbstub`` to demonstrate
-how GDB stub works.
+This is an example to demonstrate how GDB stub works.
+You can also refer to ``tests/subsys/debug/gdbstub``
+for its implementation as a Twister test.
 
 #. Open two terminal windows.
 
diff --git a/samples/subsys/debug/gdbstub/README.rst b/samples/subsys/debug/gdbstub/README.rst
deleted file mode 100644
index dc8430cd339891..00000000000000
--- a/samples/subsys/debug/gdbstub/README.rst
+++ /dev/null
@@ -1,31 +0,0 @@
-.. zephyr:code-sample:: gdb-debug
-   :name: GDB debug
-
-   Use GDB Remote Serial Protocol to debug a Zephyr application running on QEMU.
-
-Overview
-********
-
-A simple sample that can be used with QEMU to show debug using GDB
-Remote Serial Protocol (RSP) capabilities.
-
-Building and Running
-********************
-
-This application can be built and executed on QEMU as follows:
-
-.. zephyr-app-commands::
-   :zephyr-app: samples/subsys/debug/gdbstub
-   :host-os: unix
-   :board: qemu_x86
-   :goals: run
-   :compact:
-
-Open a new terminal and use gdb to connect to the running qemu as follows:
-
-.. code-block:: bash
-
-    gdb build/zephyr/zephyr.elf
-    (gdb) target remote :5678
-
-Exit QEMU by pressing :kbd:`CTRL+A` :kbd:`x`.
diff --git a/samples/subsys/debug/gdbstub/boards/qemu_x86_64.overlay b/samples/subsys/debug/gdbstub/boards/qemu_x86_64.overlay
deleted file mode 100644
index e6c560fae72751..00000000000000
--- a/samples/subsys/debug/gdbstub/boards/qemu_x86_64.overlay
+++ /dev/null
@@ -1,7 +0,0 @@
-/* SPDX-License-Identifier: Apache-2.0 */
-
-/ {
-	chosen {
-		zephyr,gdbstub-uart = &uart1;
-	};
-};
diff --git a/samples/subsys/debug/gdbstub/pytest/test_gdbstub.py b/samples/subsys/debug/gdbstub/pytest/test_gdbstub.py
deleted file mode 100755
index 41dca1cfcae9a8..00000000000000
--- a/samples/subsys/debug/gdbstub/pytest/test_gdbstub.py
+++ /dev/null
@@ -1,34 +0,0 @@
-# Copyright (c) 2023 Intel Corporation.
-#
-# SPDX-License-Identifier: Apache-2.0
-
-import os
-import subprocess
-from twister_harness import DeviceAdapter
-import sys
-import logging
-import shlex
-
-ZEPHYR_BASE = os.getenv("ZEPHYR_BASE")
-sys.path.insert(0, os.path.join(ZEPHYR_BASE, "scripts", "pylib", "twister"))
-from twisterlib.cmakecache import CMakeCache
-
-logger = logging.getLogger(__name__)
-
-
-def test_gdbstub(dut: DeviceAdapter):
-    """
-    Test gdbstub feature using a gdb script. We connect to the DUT and run some
-    basic gdb commands and evaluate return code to determine pass or failure.
-    """
-    build_dir = dut.device_config.build_dir
-    cmake_cache = CMakeCache.from_file(build_dir / 'CMakeCache.txt')
-    gdb = cmake_cache.get('CMAKE_GDB', None)
-    assert gdb
-    source_dir = cmake_cache.get('APPLICATION_SOURCE_DIR', None)
-    assert source_dir
-    cmd = [gdb, '-x', f'{source_dir}/run.gdbinit', f'{build_dir}/zephyr/zephyr.elf']
-    logger.info(f'Test command: {shlex.join(cmd)}')
-    result = subprocess.run(cmd, capture_output=True, text=True, timeout=20)
-    logger.debug('Output:\n%s' % result.stdout)
-    assert result.returncode == 0
diff --git a/samples/subsys/debug/gdbstub/run.gdbinit b/samples/subsys/debug/gdbstub/run.gdbinit
deleted file mode 100644
index abce598f54af7a..00000000000000
--- a/samples/subsys/debug/gdbstub/run.gdbinit
+++ /dev/null
@@ -1,17 +0,0 @@
-set pagination off
-#symbol-file build/zephyr/zephyr.elf
-target remote :5678
-b test
-b main.c:33
-c
-
-s
-set var a = 2
-c
-if ret == 6
-	printf "PASSED\n"
-	quit 0
-else
-	printf "FAILED\n"
-	quit 1
-end
diff --git a/samples/subsys/debug/gdbstub/sample.yaml b/samples/subsys/debug/gdbstub/sample.yaml
deleted file mode 100644
index 638c5ec16cc37b..00000000000000
--- a/samples/subsys/debug/gdbstub/sample.yaml
+++ /dev/null
@@ -1,15 +0,0 @@
-#
-# Copyright (c) 2020 intel Corporation.
-#
-# SPDX-License-Identifier: Apache-2.0
-#
-
-sample:
-  name: gdbstub sample
-tests:
-  sample.debug.gdbstub:
-    platform_allow: qemu_x86
-    harness: pytest
-    tags:
-      - debug
-      - gdbstub
diff --git a/samples/subsys/debug/gdbstub/CMakeLists.txt b/tests/subsys/debug/gdbstub/CMakeLists.txt
similarity index 59%
rename from samples/subsys/debug/gdbstub/CMakeLists.txt
rename to tests/subsys/debug/gdbstub/CMakeLists.txt
index 9759ca6c7f0c36..69377e717f56d7 100644
--- a/samples/subsys/debug/gdbstub/CMakeLists.txt
+++ b/tests/subsys/debug/gdbstub/CMakeLists.txt
@@ -2,11 +2,7 @@
 
 cmake_minimum_required(VERSION 3.20.0)
 
-if(BOARD MATCHES "qemu_x86")
-  list(APPEND QEMU_EXTRA_FLAGS -serial tcp:127.0.0.1:5678,server)
-endif()
-
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
-project(debug)
+project(debug_gdbstub)
 
 target_sources(app PRIVATE src/main.c)
diff --git a/samples/subsys/debug/gdbstub/boards/qemu_x86.overlay b/tests/subsys/debug/gdbstub/boards/qemu_x86.overlay
similarity index 100%
rename from samples/subsys/debug/gdbstub/boards/qemu_x86.overlay
rename to tests/subsys/debug/gdbstub/boards/qemu_x86.overlay
diff --git a/samples/subsys/debug/gdbstub/prj.conf b/tests/subsys/debug/gdbstub/prj.conf
similarity index 74%
rename from samples/subsys/debug/gdbstub/prj.conf
rename to tests/subsys/debug/gdbstub/prj.conf
index da68f3823c4d5c..8b490380226248 100644
--- a/samples/subsys/debug/gdbstub/prj.conf
+++ b/tests/subsys/debug/gdbstub/prj.conf
@@ -1,4 +1,5 @@
 CONFIG_GDBSTUB=y
+CONFIG_GDBSTUB_SERIAL_BACKEND=y
 CONFIG_NO_OPTIMIZATIONS=y
 CONFIG_USERSPACE=y
 CONFIG_KOBJECT_TEXT_AREA=4096
diff --git a/tests/subsys/debug/gdbstub/pytest/conftest.py b/tests/subsys/debug/gdbstub/pytest/conftest.py
new file mode 100644
index 00000000000000..12d5ced7590a95
--- /dev/null
+++ b/tests/subsys/debug/gdbstub/pytest/conftest.py
@@ -0,0 +1,25 @@
+#
+# Copyright (c) 2023 intel Corporation.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+import pytest
+
+def pytest_addoption(parser):
+    parser.addoption('--gdb_target_remote')
+    parser.addoption('--gdb_timeout')
+    parser.addoption('--gdb_script')
+
+@pytest.fixture()
+def gdb_script(request):
+    return request.config.getoption('--gdb_script')
+
+@pytest.fixture()
+def gdb_timeout(request):
+    return int(request.config.getoption('--gdb_timeout', default=60))
+
+@pytest.fixture()
+def gdb_target_remote(request):
+    return request.config.getoption('--gdb_target_remote', default=":5678")
+#
diff --git a/tests/subsys/debug/gdbstub/pytest/test_gdbstub.py b/tests/subsys/debug/gdbstub/pytest/test_gdbstub.py
new file mode 100755
index 00000000000000..fe063905df75d3
--- /dev/null
+++ b/tests/subsys/debug/gdbstub/pytest/test_gdbstub.py
@@ -0,0 +1,83 @@
+# Copyright (c) 2023 Intel Corporation.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import os
+import subprocess
+import sys
+import logging
+import shlex
+import re
+import pytest
+from twister_harness import DeviceAdapter
+
+ZEPHYR_BASE = os.getenv("ZEPHYR_BASE")
+sys.path.insert(0, os.path.join(ZEPHYR_BASE, "scripts", "pylib", "twister"))
+from twisterlib.cmakecache import CMakeCache
+
+logger = logging.getLogger(__name__)
+
+@pytest.fixture()
+def gdb_process(dut: DeviceAdapter, gdb_script, gdb_timeout, gdb_target_remote) -> subprocess.CompletedProcess:
+    build_dir = dut.device_config.build_dir
+    cmake_cache = CMakeCache.from_file(os.path.join(build_dir, 'CMakeCache.txt'))
+    gdb_exec = cmake_cache.get('CMAKE_GDB', None)
+    assert gdb_exec
+    source_dir = cmake_cache.get('APPLICATION_SOURCE_DIR', None)
+    assert source_dir
+    build_image = cmake_cache.get('BYPRODUCT_KERNEL_ELF_NAME', None)
+    assert build_image
+    gdb_log_file = os.path.join(build_dir, 'gdb.log')
+    cmd = [gdb_exec, '-batch',
+           '-ex', f'set pagination off',
+           '-ex', f'set trace-commands on',
+           '-ex', f'set logging file {gdb_log_file}',
+           '-ex', f'set logging enabled on',
+           '-ex', f'target remote {gdb_target_remote}',
+           '-x', f'{source_dir}/{gdb_script}', build_image]
+    logger.info(f'Run GDB: {shlex.join(cmd)}')
+    result = subprocess.run(cmd, capture_output=True, text=True, timeout=gdb_timeout)
+    logger.info(f'GDB ends rc={result.returncode}')
+    return result
+#
+
+@pytest.fixture(scope="module")
+def expected_app():
+    return [
+    re.compile(r"Booting from ROM"),
+    re.compile(r"Booting Zephyr OS build"),
+    re.compile(r"main\(\):enter"),
+    ]
+
+@pytest.fixture(scope="module")
+def expected_gdb():
+    return [
+    re.compile(r'Breakpoint 1 at 0x'),
+    re.compile(r'Breakpoint 2 at 0x'),
+    re.compile(r'Breakpoint 1, test '),
+    re.compile(r'Breakpoint 2, main '),
+    re.compile(r'GDB:PASSED'),
+    ]
+
+@pytest.fixture(scope="module")
+def expected_gdb_detach():
+    return [
+    re.compile(r'Inferior.*will be killed'),  # Zephyr gdbstub
+    re.compile(r'Inferior.*detached')  # QEMU gdbstub
+    ]
+
+
+def test_gdbstub(dut: DeviceAdapter, gdb_process, expected_app, expected_gdb, expected_gdb_detach):
+    """
+    Test gdbstub feature using a GDB script. We connect to the DUT, run the
+    GDB script then evaluate return code and expected patterns at the GDB
+    and Test Applicaiton outputs.
+    """
+    logger.debug(f"GDB output:\n{gdb_process.stdout}\n")
+    assert gdb_process.returncode == 0
+    assert all([ex_re.search(gdb_process.stdout, re.MULTILINE) for ex_re in expected_gdb]), 'No expected GDB output'
+    assert any([ex_re.search(gdb_process.stdout, re.MULTILINE) for ex_re in expected_gdb_detach]), 'No expected GDB quit'
+    app_output = '\n'.join(dut.readlines(print_output = False))
+    logger.debug(f"App output:\n{app_output}\n")
+    assert all([ex_re.search(app_output, re.MULTILINE) for ex_re in expected_app]), 'No expected Application output'
+#
diff --git a/samples/subsys/debug/gdbstub/src/main.c b/tests/subsys/debug/gdbstub/src/main.c
similarity index 60%
rename from samples/subsys/debug/gdbstub/src/main.c
rename to tests/subsys/debug/gdbstub/src/main.c
index 51995db4ab7370..4d54f6b2ff9c4f 100644
--- a/samples/subsys/debug/gdbstub/src/main.c
+++ b/tests/subsys/debug/gdbstub/src/main.c
@@ -20,19 +20,12 @@ static int test(void)
 	return a + b;
 }
 
-static void thread_entry(void *p1, void *p2, void *p3)
-{
-	printk("Hello from user thread!\n");
-}
-
 int main(void)
 {
 	int ret;
 
+	printk("%s():enter\n", __func__);
 	ret = test();
-	printk("%d\n", ret);
+	printk("ret=%d\n", ret);
 	return 0;
 }
-
-K_THREAD_DEFINE(thread, STACKSIZE, thread_entry, NULL, NULL, NULL,
-		7, K_USER, 0);
diff --git a/tests/subsys/debug/gdbstub/test_breakpoints.gdbinit b/tests/subsys/debug/gdbstub/test_breakpoints.gdbinit
new file mode 100644
index 00000000000000..d79e1aa5f284e7
--- /dev/null
+++ b/tests/subsys/debug/gdbstub/test_breakpoints.gdbinit
@@ -0,0 +1,17 @@
+b test
+b main.c:29
+c
+
+# break at test()
+s
+set var a = 2
+c
+
+# break at main()
+if ret == 6
+	printf "GDB:PASSED\n"
+	quit 0
+else
+	printf "GDB:FAILED\n"
+	quit 1
+end
diff --git a/tests/subsys/debug/gdbstub/testcase.yaml b/tests/subsys/debug/gdbstub/testcase.yaml
new file mode 100644
index 00000000000000..adb259b4122143
--- /dev/null
+++ b/tests/subsys/debug/gdbstub/testcase.yaml
@@ -0,0 +1,59 @@
+#
+# Copyright (c) 2020, 2023 intel Corporation.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+tests:
+  # Connect to Zephyr gdbstub and run a simple GDB script
+  debug.gdbstub.breakpoints:
+    platform_allow: qemu_x86
+    harness: pytest
+    harness_config:
+      pytest_root:
+        - "pytest/test_gdbstub.py"
+      pytest_args:
+        - "--gdb_timeout"
+        - "20"
+        - "--gdb_script"
+        - "test_breakpoints.gdbinit"
+        - "--gdb_target_remote"
+        - "tcp::5678"
+    tags:
+      - debug
+      - gdbstub
+    extra_configs:
+      # Make sure the gdbstub port chosen is unique for this test to avoid conflicts
+      # when Twister runs tests in parallel on the same host.
+      - CONFIG_QEMU_EXTRA_FLAGS="-serial tcp::5678,server"
+
+  # Connect to QEMU gdbstub backend and run the same GDB test script
+  # to check it against a reference RDP backend implementation expecting
+  # similar behavior as for Zephyr's gdbstub.
+  # Use non-default QEMU gdbstub port 1235 for this test to avoid conflicts
+  # with some other test on QEMU running in parallel.
+  debug.gdbstub_qemu.breakpoints:
+    platform_allow: qemu_x86
+    harness: pytest
+    harness_config:
+      pytest_root:
+        - "pytest/test_gdbstub.py"
+      pytest_args:
+        - "--gdb_timeout"
+        - "20"
+        - "--gdb_script"
+        - "test_breakpoints.gdbinit"
+        - "--gdb_target_remote"
+        - "tcp::1235"
+    tags:
+      - debug
+      - gdbstub
+    extra_configs:
+      # Turn off Zephyr's gdbstub for this test case.
+      - CONFIG_GDBSTUB=n
+      - CONFIG_GDBSTUB_SERIAL_BACKEND=n
+      # Make sure the gdbstub port chosen is unique for this test to avoid conflicts
+      # when Twister runs tests in parallel on the same host.
+      - CONFIG_QEMU_EXTRA_FLAGS="-S -gdb tcp::1235"
+      # Clear QEMU default 'tcp::1234'
+      - CONFIG_QEMU_GDBSERVER_LISTEN_DEV=""