doc: posix: overview: clarification on conformant implementations

Any C library with conformant implementations of POSIX features, options, or option groups can be used in place of the versions provided with Zephyr's POSIX implementation as long as there is no source licensing compatibility or linking clause violation. Implementations of such features, options, or option groups can be used in whole or in part, as long as there is no conflict with the rest of Zephyr or the application. Signed-off-by: Christopher Friedt <[email protected]>
zephyrproject-rtos · Jan 10, 2024 · b85b7a3 · b85b7a3
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diff --git a/doc/services/portability/posix/conformance/index.rst b/doc/services/portability/posix/conformance/index.rst
@@ -14,6 +14,13 @@ As per `IEEE 1003.1-2017`, this section details Zephyr's POSIX conformance.
    Zephyr's current design, some features requiring multi-process capabilities may exhibit
    undefined behaviour, which we denote with the † (obelus) symbol.
 
+.. _posix_libc_provided:
+
+.. note::
+    Features listed in various POSIX Options or Option Groups may be provided in whole or in part
+    by a conformant C library implementation. This includes (but is not limited to) POSIX
+    Extensions to the ISO C Standard (`CX`_).
+
 .. _posix_system_interfaces:
 
 POSIX System Interfaces
@@ -143,3 +150,5 @@ XSI System Interfaces
     :ref:`_POSIX_THREAD_ATTR_STACKADDR<posix_option_thread_attr_stackaddr>`, 200809L, :kconfig:option:`CONFIG_PTHREAD`
     :ref:`_POSIX_THREAD_ATTR_STACKSIZE<posix_option_thread_attr_stacksize>`, 200809L, :kconfig:option:`CONFIG_PTHREAD`
     _POSIX_THREAD_PROCESS_SHARED, -1,
+
+.. _CX: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap01.html