build: change ABI versioning to global

[dpdk.git] / doc / guides / contributing / coding_style.rst

diff --git a/doc/guides/contributing/coding_style.rst b/doc/guides/contributing/coding_style.rst
index d5fe67f..841ef6d 100644 (file)
--- a/doc/guides/contributing/coding_style.rst
+++ b/doc/guides/contributing/coding_style.rst
@@ -1,3 +1,6 @@
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright 2018 The DPDK contributors
+

 .. _coding_style:
 
 DPDK Coding Style
 .. _coding_style:
 
 DPDK Coding Style


@@ -244,6 +247,15 @@ Structure Declarations
 * Use of the structures should be by separate variable declarations and those declarations must be extern if they are declared in a header file.
 * Externally visible structure definitions should have the structure name prefixed by ``rte_`` to avoid namespace collisions.
 
 * Use of the structures should be by separate variable declarations and those declarations must be extern if they are declared in a header file.
 * Externally visible structure definitions should have the structure name prefixed by ``rte_`` to avoid namespace collisions.
 

+.. note::
+
+    Uses of ``bool`` in structures are not preferred as is wastes space and
+    it's also not clear as to what type size the bool is. A preferred use of
+    ``bool`` is mainly as a return type from functions that return true/false,
+    and maybe local variable functions.
+
+    Ref: `LKML <https://lkml.org/lkml/2017/11/21/384>`_
+

 Queues
 ~~~~~~
 
 Queues
 ~~~~~~
 


@@ -614,15 +626,15 @@ In the DPDK environment, use the logging interface provided:
   * is DEBUG) */
  rte_log_set_level(my_logtype2, RTE_LOG_NOTICE);
 
   * is DEBUG) */
  rte_log_set_level(my_logtype2, RTE_LOG_NOTICE);
 

- /* enable all PMD logs (whose identifier string starts with "pmd") */
- rte_log_set_level_regexp("pmd.*", RTE_LOG_DEBUG);
+ /* enable all PMD logs (whose identifier string starts with "pmd.") */
+ rte_log_set_level_pattern("pmd.*", RTE_LOG_DEBUG);

 
  /* log in debug level */
  rte_log_set_global_level(RTE_LOG_DEBUG);
 
  /* log in debug level */
  rte_log_set_global_level(RTE_LOG_DEBUG);

- RTE_LOG(DEBUG, my_logtype1, "this is is a debug level message\n");
- RTE_LOG(INFO, my_logtype1, "this is is a info level message\n");
- RTE_LOG(WARNING, my_logtype1, "this is is a warning level message\n");
- RTE_LOG(WARNING, my_logtype2, "this is is a debug level message (not displayed)\n");
+ RTE_LOG(DEBUG, my_logtype1, "this is a debug level message\n");
+ RTE_LOG(INFO, my_logtype1, "this is a info level message\n");
+ RTE_LOG(WARNING, my_logtype1, "this is a warning level message\n");
+ RTE_LOG(WARNING, my_logtype2, "this is a debug level message (not displayed)\n");

 
  /* log in info level */
  rte_log_set_global_level(RTE_LOG_INFO);
 
  /* log in info level */
  rte_log_set_global_level(RTE_LOG_INFO);


@@ -694,6 +706,56 @@ Control Statements
                  /* NOTREACHED */
          }
 
                  /* NOTREACHED */
          }
 

+Dynamic Logging
+---------------
+
+DPDK provides infrastructure to perform logging during runtime. This is very
+useful for enabling debug output without recompilation. To enable or disable
+logging of a particular topic, the ``--log-level`` parameter can be provided
+to EAL, which will change the log level. DPDK code can register topics,
+which allows the user to adjust the log verbosity for that specific topic.
+
+In general, the naming scheme is as follows: ``type.section.name``
+
+ * Type is the type of component, where ``lib``, ``pmd``, ``bus`` and ``user``
+   are the common options.
+ * Section refers to a specific area, for example a poll-mode-driver for an
+   ethernet device would use ``pmd.net``, while an eventdev PMD uses
+   ``pmd.event``.
+ * The name identifies the individual item that the log applies to.
+   The name section must align with
+   the directory that the PMD code resides. See examples below for clarity.
+
+Examples:
+
+ * The virtio network PMD in ``drivers/net/virtio`` uses ``pmd.net.virtio``
+ * The eventdev software poll mode driver in ``drivers/event/sw`` uses ``pmd.event.sw``
+ * The octeontx mempool driver in ``drivers/mempool/octeontx`` uses ``pmd.mempool.octeontx``
+ * The DPDK hash library in ``lib/librte_hash`` uses ``lib.hash``
+
+Specializations
+~~~~~~~~~~~~~~~
+
+In addition to the above logging topic, any PMD or library can further split
+logging output by using "specializations". A specialization could be the
+difference between initialization code, and logs of events that occur at runtime.
+
+An example could be the initialization log messages getting one
+specialization, while another specialization handles mailbox command logging.
+Each PMD, library or component can create as many specializations as required.
+
+A specialization looks like this:
+
+ * Initialization output: ``type.section.name.init``
+ * PF/VF mailbox output: ``type.section.name.mbox``
+
+A real world example is the i40e poll mode driver which exposes two
+specializations, one for initialization ``pmd.net.i40e.init`` and the other for
+the remaining driver logs ``pmd.net.i40e.driver``.
+
+Note that specializations have no formatting rules, but please follow
+a precedent if one exists. In order to see all current log topics and
+specializations, run the ``app/test`` binary, and use the ``dump_log_types``

 
 Python Code
 -----------
 
 Python Code
 -----------


@@ -741,9 +803,8 @@ lpm, etc. For drivers, the same format of Makefile is used.
        CFLAGS += -O3
        CFLAGS += $(WERROR_FLAGS)
 
        CFLAGS += -O3
        CFLAGS += $(WERROR_FLAGS)
 

-       # the symbol version information for the library, and .so version
+       # the symbol version information for the library

        EXPORT_MAP := rte_<name>_version.map
        EXPORT_MAP := rte_<name>_version.map

-       LIBABIVER := 1

 
        # all source filenames are stored in SRCS-y
        SRCS-$(CONFIG_RTE_LIBRTE_<NAME>) += rte_<name>.c
 
        # all source filenames are stored in SRCS-y
        SRCS-$(CONFIG_RTE_LIBRTE_<NAME>) += rte_<name>.c


@@ -763,10 +824,10 @@ format.
 .. code-block:: python
 
        sources = files('file1.c', ...)
 .. code-block:: python
 
        sources = files('file1.c', ...)

-       headers = files('file1.c', ...)
+       headers = files('file1.h', ...)

 
 
 
 

-The will build based on a number of conventions and assumptions within the DPDK
+This will build based on a number of conventions and assumptions within the DPDK

 itself, for example, that the library name is the same as the directory name in
 which the files are stored.
 
 itself, for example, that the library name is the same as the directory name in
 which the files are stored.
 


@@ -790,12 +851,15 @@ allow_experimental_apis
 build
        **Default Value = true**
        Used to optionally compile a library, based on its dependencies or
 build
        **Default Value = true**
        Used to optionally compile a library, based on its dependencies or

-       environment. A simple example of use would be:
+       environment. When set to "false" the ``reason`` value, explained below, should
+       also be set to explain to the user why the component is not being built.
+       A simple example of use would be:

 
 .. code-block:: python
 
 
 .. code-block:: python
 

-       if host_machine.system() != 'linux'
+       if not is_linux

                build = false
                build = false

+               reason = 'only supported on Linux'

        endif
 
 
        endif
 
 


@@ -876,10 +940,19 @@ objs
        objects that were compiled up as part of another target given in the
        included library ``meson.build`` file.
 
        objects that were compiled up as part of another target given in the
        included library ``meson.build`` file.
 

-version
-       **Default Value = 1**.
-       Specifies the ABI version of the library, and is used as the major
-       version number of the resulting ``.so`` library.
+reason
+       **Default Value = '<unknown reason>'**.
+       This variable should be used when a library is not to be built i.e. when
+       ``build`` is set to "false", to specify the reason why a library will not be
+       built. For missing dependencies this should be of the form
+       ``'missing dependency, "libname"'``.
+
+use_function_versioning
+       **Default Value = false**.
+       Specifies if the library in question has ABI versioned functions. If it
+       has, this value should be set to ensure that the C files are compiled
+       twice with suitable parameters for each of shared or static library
+       builds.

 
 Meson Build File Contents - Drivers
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Meson Build File Contents - Drivers
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


@@ -929,6 +1002,9 @@ pkgconfig_extra_libs
        using static libraries. Anything added here will be appended to the end
        of the ``pkgconfig --libs`` output.
 
        using static libraries. Anything added here will be appended to the end
        of the ``pkgconfig --libs`` output.
 

+reason
+       As above.
+

 sources [mandatory]
        As above
 
 sources [mandatory]
        As above