[Buildroot] [PATCH 1/2] package/libiio: fix python bindings without glibc utils

[Buildroot] [PATCH 1/2] package/libiio: fix python bindings without glibc utils

[Marcus Hoffmann via buildroot]

Libiio python bindings use ctypes and specifically the find_library()
function from there to load the libiio.so shared library. This is not
working unless glibc utils (specifically ldconfig) is installed to the
target (alternatively the target would need gcc or binutils, for objdump
or ld).

The easy fix here is to just bypass the find_library() machinery
altogether as it's not needed on a buildroot system.

Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
---
 ...-bindings-python-fix-library-loading.patch | 41 +++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 package/libiio/0001-bindings-python-fix-library-loading.patch

diff --git a/package/libiio/0001-bindings-python-fix-library-loading.patch b/package/libiio/0001-bindings-python-fix-library-loading.patch
new file mode 100644
index 0000000000..f8715b4c5b
--- /dev/null
+++ b/package/libiio/0001-bindings-python-fix-library-loading.patch
@@ -0,0 +1,41 @@
+From 4d4d17e2810f793b9f7fd8acad2a3c551dbff2b5 Mon Sep 17 00:00:00 2001
+From: Marcus Hoffmann <marcus.hoffmann@othermo.de>
+Date: Fri, 31 Mar 2023 20:13:07 +0200
+Subject: [PATCH] bindings: python: fix library loading
+
+On Linux the find_library() function requires ld, gcc, objdump
+or ldconfig on the target, which might not be present on a
+buildroot system. [1]
+We do not actually need this function at all, as we know the iio library
+will be referencable in the system under the name "libiio.so".
+So instead of kicking of this complicated cross-platform/cross-distro
+compatible machinery, we just pass in the name of the library we already
+know.
+
+[1] https://docs.python.org/3/library/ctypes.html#finding-shared-libraries
+
+Upstream: N/A, buildroot doesn't have to care about different OS's and
+distro setups, so we can just hardcode the lib name, but we cannot
+submit that upstream.
+
+Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
+---
+ bindings/python/iio.py | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/bindings/python/iio.py b/bindings/python/iio.py
+index b91260cc..bde17694 100644
+--- a/bindings/python/iio.py
++++ b/bindings/python/iio.py
+@@ -224,7 +224,7 @@ else:
+     # Non-windows, possibly Posix system
+     _iiolib = "iio"
+ 
+-_lib = _cdll(find_library(_iiolib), use_errno=True, use_last_error=True)
++_lib = _cdll("libiio.so", use_errno=True, use_last_error=True)
+ 
+ _get_backends_count = _lib.iio_get_backends_count
+ _get_backends_count.restype = c_uint
+-- 
+2.25.1
+
-- 
2.52.0

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[Buildroot] [PATCH 2/2] support/testing: add libiio python bindings runtime test

[Marcus Hoffmann via buildroot]

Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
---
 .../tests/package/sample_libiio_bindings_python.py  |  3 +++
 .../tests/package/test_libiio_bindings_python.py    | 13 +++++++++++++
 2 files changed, 16 insertions(+)
 create mode 100644 support/testing/tests/package/sample_libiio_bindings_python.py
 create mode 100644 support/testing/tests/package/test_libiio_bindings_python.py

diff --git a/support/testing/tests/package/sample_libiio_bindings_python.py b/support/testing/tests/package/sample_libiio_bindings_python.py
new file mode 100644
index 0000000000..74452192c2
--- /dev/null
+++ b/support/testing/tests/package/sample_libiio_bindings_python.py
@@ -0,0 +1,3 @@
+import iio
+
+assert len(iio.scan_contexts()) == 1
diff --git a/support/testing/tests/package/test_libiio_bindings_python.py b/support/testing/tests/package/test_libiio_bindings_python.py
new file mode 100644
index 0000000000..e8cf5c3d13
--- /dev/null
+++ b/support/testing/tests/package/test_libiio_bindings_python.py
@@ -0,0 +1,13 @@
+from tests.package.test_python import TestPythonPackageBase
+
+
+class TestLibiioBindingsPython(TestPythonPackageBase):
+    __test__ = True
+    config = TestPythonPackageBase.config + \
+        """
+        BR2_PACKAGE_PYTHON3=y
+        BR2_PACKAGE_LIBIIO=y
+        BR2_PACKAGE_LIBIIO_BINDINGS_PYTHON=y
+        """
+    sample_scripts = ["tests/package/sample_libiio_bindings_python.py"]
+    timeout = 10
-- 
2.52.0

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Re: [Buildroot] [PATCH 1/2] package/libiio: fix python bindings without glibc utils

[Fiona Klute via buildroot]

Am 22.12.25 um 18:26 schrieb Marcus Hoffmann via buildroot:
> Libiio python bindings use ctypes and specifically the find_library()
> function from there to load the libiio.so shared library. This is not
> working unless glibc utils (specifically ldconfig) is installed to the
> target (alternatively the target would need gcc or binutils, for objdump
> or ld).
> 
> The easy fix here is to just bypass the find_library() machinery
> altogether as it's not needed on a buildroot system.
> 
> Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>

Tested-by: Fiona Klute <fiona.klute@gmx.de>

The issue also affects musl, where ldconfig simply doesn't exist. It's 
clearly a bug in Python (where an open PR exists for years [1], and 
Alpine has been carrying a musl-specific patch for >10 years by now), 
but I think it's good to apply a workaround that's so simple.

Thank you,
Fiona

[1] https://github.com/python/cpython/pull/18380

> ---
>   ...-bindings-python-fix-library-loading.patch | 41 +++++++++++++++++++
>   1 file changed, 41 insertions(+)
>   create mode 100644 package/libiio/0001-bindings-python-fix-library-loading.patch
> 
> diff --git a/package/libiio/0001-bindings-python-fix-library-loading.patch b/package/libiio/0001-bindings-python-fix-library-loading.patch
> new file mode 100644
> index 0000000000..f8715b4c5b
> --- /dev/null
> +++ b/package/libiio/0001-bindings-python-fix-library-loading.patch
> @@ -0,0 +1,41 @@
> +From 4d4d17e2810f793b9f7fd8acad2a3c551dbff2b5 Mon Sep 17 00:00:00 2001
> +From: Marcus Hoffmann <marcus.hoffmann@othermo.de>
> +Date: Fri, 31 Mar 2023 20:13:07 +0200
> +Subject: [PATCH] bindings: python: fix library loading
> +
> +On Linux the find_library() function requires ld, gcc, objdump
> +or ldconfig on the target, which might not be present on a
> +buildroot system. [1]
> +We do not actually need this function at all, as we know the iio library
> +will be referencable in the system under the name "libiio.so".
> +So instead of kicking of this complicated cross-platform/cross-distro
> +compatible machinery, we just pass in the name of the library we already
> +know.
> +
> +[1] https://docs.python.org/3/library/ctypes.html#finding-shared-libraries
> +
> +Upstream: N/A, buildroot doesn't have to care about different OS's and
> +distro setups, so we can just hardcode the lib name, but we cannot
> +submit that upstream.
> +
> +Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
> +---
> + bindings/python/iio.py | 2 +-
> + 1 file changed, 1 insertion(+), 1 deletion(-)
> +
> +diff --git a/bindings/python/iio.py b/bindings/python/iio.py
> +index b91260cc..bde17694 100644
> +--- a/bindings/python/iio.py
> ++++ b/bindings/python/iio.py
> +@@ -224,7 +224,7 @@ else:
> +     # Non-windows, possibly Posix system
> +     _iiolib = "iio"
> +
> +-_lib = _cdll(find_library(_iiolib), use_errno=True, use_last_error=True)
> ++_lib = _cdll("libiio.so", use_errno=True, use_last_error=True)
> +
> + _get_backends_count = _lib.iio_get_backends_count
> + _get_backends_count.restype = c_uint
> +--
> +2.25.1
> +

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Re: [Buildroot] [PATCH 1/2] package/libiio: fix python bindings without glibc utils

[Thomas Petazzoni via buildroot]

Hello Marcus,

On Mon, 22 Dec 2025 18:26:36 +0100
Marcus Hoffmann via buildroot <buildroot@buildroot.org> wrote:

> Libiio python bindings use ctypes and specifically the find_library()
> function from there to load the libiio.so shared library. This is not
> working unless glibc utils (specifically ldconfig) is installed to the
> target (alternatively the target would need gcc or binutils, for objdump
> or ld).
> 
> The easy fix here is to just bypass the find_library() machinery
> altogether as it's not needed on a buildroot system.
> 
> Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
> ---
>  ...-bindings-python-fix-library-loading.patch | 41 +++++++++++++++++++
>  1 file changed, 41 insertions(+)
>  create mode 100644 package/libiio/0001-bindings-python-fix-library-loading.patch

Thanks, I have applied both patches. However I must admit that for
PATCH 1/2, I would probably have preferred to backport the on-going PR
on cpython, which fixes the problem for all cases, not just libiio.

Reading the discussion on the PR, I think it was improperly presented
as being needed for "musl", and used only for musl. I would suggest to
not present it as something musl-specific, but rather something that
makes the lookup for the C/C++ libraries more portable (and therefore
probably drop using ldconfig entirely). This would have addressed the
concern raised on the PR that this is musl specific, and musl is not a
supported platform, yadayadayada.

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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Re: [Buildroot] [PATCH 1/2] package/libiio: fix python bindings without glibc utils

[Fiona Klute via buildroot]

Am 27.12.25 um 16:57 schrieb Thomas Petazzoni via buildroot:
> Hello Marcus,
> 
> On Mon, 22 Dec 2025 18:26:36 +0100
> Marcus Hoffmann via buildroot <buildroot@buildroot.org> wrote:
> 
>> Libiio python bindings use ctypes and specifically the find_library()
>> function from there to load the libiio.so shared library. This is not
>> working unless glibc utils (specifically ldconfig) is installed to the
>> target (alternatively the target would need gcc or binutils, for objdump
>> or ld).
>>
>> The easy fix here is to just bypass the find_library() machinery
>> altogether as it's not needed on a buildroot system.
>>
>> Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
>> ---
>>   ...-bindings-python-fix-library-loading.patch | 41 +++++++++++++++++++
>>   1 file changed, 41 insertions(+)
>>   create mode 100644 package/libiio/0001-bindings-python-fix-library-loading.patch
> 
> Thanks, I have applied both patches. However I must admit that for
> PATCH 1/2, I would probably have preferred to backport the on-going PR
> on cpython, which fixes the problem for all cases, not just libiio.
> 
> Reading the discussion on the PR, I think it was improperly presented
> as being needed for "musl", and used only for musl. I would suggest to
> not present it as something musl-specific, but rather something that
> makes the lookup for the C/C++ libraries more portable (and therefore
> probably drop using ldconfig entirely). This would have addressed the
> concern raised on the PR that this is musl specific, and musl is not a
> supported platform, yadayadayada.
Unfortunately the CPython PR [1] as it is actually *is* musl specific, 
importing it would only help for musl-based systems (fine for my builds, 
but not a general solution). The current ctypes.util.find_library() 
implementation using glibc executables has issues beyond musl 
compatibility as Marcus' point about missing ldconfig shows, but that 
hasn't even been mentioned in the PR discussion.

Best regards,
Fiona


[1] https://github.com/python/cpython/pull/18380
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Re: [Buildroot] [PATCH 1/2] package/libiio: fix python bindings without glibc utils

[Arnout Vandecappelle via buildroot]

In reply of:
> Libiio python bindings use ctypes and specifically the find_library()
> function from there to load the libiio.so shared library. This is not
> working unless glibc utils (specifically ldconfig) is installed to the
> target (alternatively the target would need gcc or binutils, for objdump
> or ld).
> 
> The easy fix here is to just bypass the find_library() machinery
> altogether as it's not needed on a buildroot system.
> 
> Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>

Applied to 2025.02.x and 2025.11.x. Thanks

> ---
>  ...-bindings-python-fix-library-loading.patch | 41 +++++++++++++++++++
>  1 file changed, 41 insertions(+)
>  create mode 100644 package/libiio/0001-bindings-python-fix-library-loading.patch
> 
> diff --git a/package/libiio/0001-bindings-python-fix-library-loading.patch b/package/libiio/0001-bindings-python-fix-library-loading.patch
> new file mode 100644
> index 0000000000..f8715b4c5b
> --- /dev/null
> +++ b/package/libiio/0001-bindings-python-fix-library-loading.patch
> @@ -0,0 +1,41 @@
> +From 4d4d17e2810f793b9f7fd8acad2a3c551dbff2b5 Mon Sep 17 00:00:00 2001
> +From: Marcus Hoffmann <marcus.hoffmann@othermo.de>
> +Date: Fri, 31 Mar 2023 20:13:07 +0200
> +Subject: [PATCH] bindings: python: fix library loading
> +
> +On Linux the find_library() function requires ld, gcc, objdump
> +or ldconfig on the target, which might not be present on a
> +buildroot system. [1]
> +We do not actually need this function at all, as we know the iio library
> +will be referencable in the system under the name "libiio.so".
> +So instead of kicking of this complicated cross-platform/cross-distro
> +compatible machinery, we just pass in the name of the library we already
> +know.
> +
> +[1] https://docs.python.org/3/library/ctypes.html#finding-shared-libraries
> +
> +Upstream: N/A, buildroot doesn't have to care about different OS's and
> +distro setups, so we can just hardcode the lib name, but we cannot
> +submit that upstream.
> +
> +Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
> +---
> + bindings/python/iio.py | 2 +-
> + 1 file changed, 1 insertion(+), 1 deletion(-)
> +
> +diff --git a/bindings/python/iio.py b/bindings/python/iio.py
> +index b91260cc..bde17694 100644
> +--- a/bindings/python/iio.py
> ++++ b/bindings/python/iio.py
> +@@ -224,7 +224,7 @@ else:
> +     # Non-windows, possibly Posix system
> +     _iiolib = "iio"
> + 
> +-_lib = _cdll(find_library(_iiolib), use_errno=True, use_last_error=True)
> ++_lib = _cdll("libiio.so", use_errno=True, use_last_error=True)
> + 
> + _get_backends_count = _lib.iio_get_backends_count
> + _get_backends_count.restype = c_uint
> +-- 
> +2.25.1
> +
> -- 
> 2.52.0
> 
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Re: [Buildroot] [PATCH 2/2] support/testing: add libiio python bindings runtime test

[Arnout Vandecappelle via buildroot]

In reply of:
> Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>

Applied to 2025.02.x and 2025.11.x. Thanks

> ---
>  .../tests/package/sample_libiio_bindings_python.py  |  3 +++
>  .../tests/package/test_libiio_bindings_python.py    | 13 +++++++++++++
>  2 files changed, 16 insertions(+)
>  create mode 100644 support/testing/tests/package/sample_libiio_bindings_python.py
>  create mode 100644 support/testing/tests/package/test_libiio_bindings_python.py
> 
> diff --git a/support/testing/tests/package/sample_libiio_bindings_python.py b/support/testing/tests/package/sample_libiio_bindings_python.py
> new file mode 100644
> index 0000000000..74452192c2
> --- /dev/null
> +++ b/support/testing/tests/package/sample_libiio_bindings_python.py
> @@ -0,0 +1,3 @@
> +import iio
> +
> +assert len(iio.scan_contexts()) == 1
> diff --git a/support/testing/tests/package/test_libiio_bindings_python.py b/support/testing/tests/package/test_libiio_bindings_python.py
> new file mode 100644
> index 0000000000..e8cf5c3d13
> --- /dev/null
> +++ b/support/testing/tests/package/test_libiio_bindings_python.py
> @@ -0,0 +1,13 @@
> +from tests.package.test_python import TestPythonPackageBase
> +
> +
> +class TestLibiioBindingsPython(TestPythonPackageBase):
> +    __test__ = True
> +    config = TestPythonPackageBase.config + \
> +        """
> +        BR2_PACKAGE_PYTHON3=y
> +        BR2_PACKAGE_LIBIIO=y
> +        BR2_PACKAGE_LIBIIO_BINDINGS_PYTHON=y
> +        """
> +    sample_scripts = ["tests/package/sample_libiio_bindings_python.py"]
> +    timeout = 10
> -- 
> 2.52.0
> 
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