Revert "zbus: Add linker support and documentation for the zbus port"

This reverts commit 2a1b23802a.

.codespellrc

@@ -9,7 +9,6 @@ exclude-file = .codespell-ignore-lines
 skip =
   LICENSE,
   */CODEOWNERS,
-  */system/zbus/images/*,
 
 # Ignore seemingly misspelled words.
 #   lowercase: case insensitive

Documentation/applications/system/zbus/index.rst

@@ -1,210 +0,0 @@
-==========================
-``zbus`` ZBus message bus
-==========================
-
-Port of the `zbus <https://docs.zephyrproject.org/latest/services/zbus/index.html>`_
-message bus to NuttX, built entirely on native NuttX primitives.  ZBus
-implements many-to-many communication through **channels** (typed shared
-messages) observed by **observers**, keeping publishers and consumers
-fully decoupled.
-
-.. figure:: images/zbus_overview.svg
-    :alt: zbus usage overview
-    :width: 75%
-
-    A typical zbus application architecture.
-
-Channels and observers are defined statically, in any source file, with
-declarative macros.  The definitions are collected at link time through
-iterable sections (see the Iterable Sections component documentation) --
-there is no runtime registration and no central list to maintain.
-
-.. figure:: images/zbus_anatomy.svg
-    :alt: zbus anatomy
-    :width: 70%
-
-    ZBus anatomy: channels, observers and observations.
-
-Observer types
-==============
-
-.. figure:: images/zbus_type_of_observers.svg
-    :alt: zbus observer types
-    :width: 70%
-
-    The four observer types.
-
-========================  ===================================================
-Type                      Behavior
-========================  ===================================================
-Listener                  Callback executed synchronously in the publisher
-                          context (``ZBUS_LISTENER_DEFINE``).
-Subscriber                Receives channel references through a message
-                          queue; waits with ``zbus_sub_wait()``
-                          (``ZBUS_SUBSCRIBER_DEFINE``).
-Message subscriber        Receives a *copy* of every published message, in
-                          order; waits with ``zbus_sub_wait_msg()``
-                          (``ZBUS_MSG_SUBSCRIBER_DEFINE``,
-                          ``CONFIG_ZBUS_MSG_SUBSCRIBER``).
-Async listener            Callback executed on a dedicated task with a
-                          copy of the message
-                          (``ZBUS_ASYNC_LISTENER_DEFINE``,
-                          ``CONFIG_ZBUS_ASYNC_LISTENER``).
-========================  ===================================================
-
-Runtime observers (``zbus_chan_add_obs()``/``zbus_chan_rm_obs()``,
-``CONFIG_ZBUS_RUNTIME_OBSERVERS``), per-observation notification masks,
-observer enable/disable, message validators and channel user data are
-also supported.
-
-.. figure:: images/zbus_observation_mask.svg
-    :alt: zbus observation mask
-    :width: 75%
-
-    Observer enable/disable and per-observation masks: disabling the
-    observer (b) silences every channel; masking observations (c, d)
-    silences individual channels.
-
-Example
-=======
-
-The figure below shows the kind of decoupled architecture zbus enables:
-every block only talks to channels, so each one can be replaced without
-touching the others.
-
-.. figure:: images/zbus_operations.svg
-    :alt: zbus sensor-based application
-    :width: 85%
-
-    A sensor-based application built on zbus.
-
-.. code-block:: c
-
-   #include <system/zbus.h>
-
-   struct acc_msg
-   {
-     int x;
-     int y;
-     int z;
-   };
-
-   static void listener_cb(const struct zbus_channel *chan)
-   {
-     const struct acc_msg *msg = zbus_chan_const_msg(chan);
-     printf("x=%d y=%d z=%d\n", msg->x, msg->y, msg->z);
-   }
-
-   ZBUS_LISTENER_DEFINE(acc_listener, listener_cb);
-   ZBUS_SUBSCRIBER_DEFINE(acc_subscriber, 4);
-
-   ZBUS_CHAN_DEFINE(acc_chan,                      /* Name */
-                    struct acc_msg,                /* Message type */
-                    NULL,                          /* Validator */
-                    NULL,                          /* User data */
-                    ZBUS_OBSERVERS(acc_listener,   /* Observers, in */
-                                   acc_subscriber),/* priority order */
-                    ZBUS_MSG_INIT(.x = 0, .y = 0, .z = 0));
-
-   /* Publisher: */
-
-   struct acc_msg msg = { 1, 10, 100 };
-   zbus_chan_pub(&acc_chan, &msg, 1000);
-
-   /* Subscriber thread: */
-
-   const struct zbus_channel *chan;
-   if (zbus_sub_wait(&acc_subscriber, &chan, ZBUS_FOREVER) == 0)
-     {
-       zbus_chan_read(chan, &msg, 500);
-     }
-
-A complete runnable example is available in ``apps/examples/zbus``
-(``CONFIG_EXAMPLES_ZBUS``), and a cmocka test suite covering the whole
-API in ``apps/testing/zbus`` (``CONFIG_TESTING_ZBUS``).
-
-Not ported
-==========
-
-The following Zephyr zbus features are **not available** in this port:
-
-* **Multi-domain proxy agent** (``CONFIG_ZBUS_PROXY_AGENT``): bridges
-  channels between domains/cores over IPC.  Experimental upstream and
-  tied to the Zephyr IPC service; a NuttX equivalent would be built on
-  rpmsg and is left as future work.
-* **Publishing from interrupt handlers**: the Zephyr original allows
-  ``zbus_chan_pub()`` from ISRs with ``K_NO_WAIT``.  This port is a
-  userspace library and its primitives (semaphores, message queues, lazy
-  initialization) are not ISR-safe: interrupt handling belongs to the
-  driver, which should hand the data to a thread (the usual NuttX
-  pattern) that then publishes it.  ``test_timer_driven_publisher`` in
-  ``apps/testing/zbus`` shows the pattern with a kernel timer interrupt
-  delivering a signal to a sampling thread.
-* **Priority boost (Highest Locker Protocol)**
-  (``CONFIG_ZBUS_PRIORITY_BOOST``): the Zephyr hand-rolled protection
-  against priority inversion during the notification process.  Not
-  needed: enable the native ``CONFIG_PRIORITY_INHERITANCE`` so the
-  channel semaphores get equivalent protection from the kernel.
-* **net_buf pools and pool isolation**
-  (``CONFIG_ZBUS_MSG_SUBSCRIBER_BUF_*``): obsolete by design in this
-  port -- message queues copy the payload on ``mq_send``, so no shared
-  reference-counted buffers exist at all.
-* **Static/user-provided runtime observer nodes**
-  (``CONFIG_ZBUS_RUNTIME_OBSERVERS_NODE_ALLOC_STATIC/NONE``): runtime
-  observer nodes are always heap-allocated in this port.
-
-Differences from the Zephyr original
-====================================
-
-* Timeouts are plain milliseconds (``int32_t``): ``ZBUS_NO_WAIT`` (0) and
-  ``ZBUS_FOREVER`` (-1) replace ``K_NO_WAIT``/``K_FOREVER``.
-* Subscriber queues are POSIX message queues opened lazily on first API
-  use through the kernel ``file_mq_*`` interface, making them usable from
-  any task (a ``mqd_t`` descriptor would die with the opening task).
-* Initialization is lazy (``pthread_once`` on the first API call)
-  replacing the Zephyr ``SYS_INIT`` hook; no explicit init call is
-  needed.
-* Async listeners run on a dedicated task per listener (spawned on
-  first use; priority and stack size are configurable) instead of the
-  Zephyr system work queue.
-
-Configuration
-=============
-
-Requirements:
-
-* The board linker script must provide the zbus iterable sections, either
-  by including ``<nuttx/linker/common-rom.ld>`` inside ``.text`` (see the
-  ``linum-stm32h753bi`` board) or through
-  ``CONFIG_ITERABLE_SECTIONS_LINKER_INSERT``
-  (zero-touch mode; see its help text for the MEMORY-layout constraint).
-* ``CONFIG_MQ_MAXMSGSIZE`` must be at least
-  ``CONFIG_ZBUS_MSG_SUBSCRIBER_MAX_MSG_SIZE`` plus the size of a pointer
-  when message subscribers or async listeners are used, otherwise their
-  queues fail to open with ``-EINVAL``.
-* FLAT build (the library uses the kernel ``file_mq_*`` interface
-  directly).
-
-Main options:
-
-* ``CONFIG_ZBUS`` -- enable the library.
-* ``CONFIG_ZBUS_CHANNEL_NAME`` / ``CONFIG_ZBUS_OBSERVER_NAME`` -- name
-  fields and lookup by name.
-* ``CONFIG_ZBUS_CHANNEL_ID`` -- numeric channel identifiers
-  (``ZBUS_CHAN_DEFINE_WITH_ID``, ``zbus_chan_from_id()``).
-* ``CONFIG_ZBUS_MSG_SUBSCRIBER`` -- message subscribers
-  (+ ``_MAX_MSG_SIZE``, ``_QUEUE_SIZE``).
-* ``CONFIG_ZBUS_ASYNC_LISTENER`` -- async listeners (+ ``_PRIORITY``,
-  ``_STACKSIZE`` of their tasks).
-* ``CONFIG_ZBUS_RUNTIME_OBSERVERS`` -- runtime observers.
-* ``CONFIG_ZBUS_CHANNEL_PUBLISH_STATS`` -- publish timestamp/count.
-* ``CONFIG_ZBUS_ASSERT_MOCK`` -- invalid parameters return ``-EFAULT``
-  instead of asserting (for tests).
-
-Credits
-=======
-
-The zbus design and the diagrams in this page come from the upstream
-`Zephyr zbus documentation
-<https://docs.zephyrproject.org/latest/services/zbus/index.html>`_
-by Rodrigo Peixoto and contributors (Apache License 2.0).

include/nuttx/linker/common-insert.ld

@@ -54,11 +54,6 @@ SECTIONS
 {
     .iterable_sections : SUBALIGN(4)
     {
-#ifdef CONFIG_ZBUS
-        ITERABLE_SECTION(zbus_channel)
-        ITERABLE_SECTION(zbus_observer)
-        ITERABLE_SECTION(zbus_channel_observation)
-#endif
     }
 }
 INSERT AFTER .text;

include/nuttx/linker/common-ram.ld

@@ -40,8 +40,4 @@
  * sections; blocks are added below, each guarded by its Kconfig option.
  */
 
-/* zbus needs no RAM iterable sections: notification masks live in .bss
- * and are initialized at runtime from ROM-preserved values.
- */
-
 #endif /* !CONFIG_ITERABLE_SECTIONS_LINKER_INSERT */

include/nuttx/linker/common-rom.ld

@@ -44,10 +44,4 @@
  *   #endif
  */
 
-#ifdef CONFIG_ZBUS
-ITERABLE_SECTION(zbus_channel)
-ITERABLE_SECTION(zbus_observer)
-ITERABLE_SECTION(zbus_channel_observation)
-#endif
-
 #endif /* !CONFIG_ITERABLE_SECTIONS_LINKER_INSERT */