ceph/src/spdk/dpdk/lib/librte_eal/common/include/rte_compat.h

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2015 Neil Horman <nhorman@tuxdriver.com>.
   3  * All rights reserved.
   4  */
   5
   6 #ifndef _RTE_COMPAT_H_
   7 #define _RTE_COMPAT_H_
   8 #include <rte_common.h>
   9
  10 #ifdef RTE_BUILD_SHARED_LIB
  11
  12 /*
  13  * Provides backwards compatibility when updating exported functions.
  14  * When a symol is exported from a library to provide an API, it also provides a
  15  * calling convention (ABI) that is embodied in its name, return type,
  16  * arguments, etc.  On occasion that function may need to change to accommodate
  17  * new functionality, behavior, etc.  When that occurs, it is desirable to
  18  * allow for backwards compatibility for a time with older binaries that are
  19  * dynamically linked to the dpdk.  To support that, the __vsym and
  20  * VERSION_SYMBOL macros are created.  They, in conjunction with the
  21  * <library>_version.map file for a given library allow for multiple versions of
  22  * a symbol to exist in a shared library so that older binaries need not be
  23  * immediately recompiled.
  24  *
  25  * Refer to the guidelines document in the docs subdirectory for details on the
  26  * use of these macros
  27  */
  28
  29 /*
  30  * Macro Parameters:
  31  * b - function base name
  32  * e - function version extension, to be concatenated with base name
  33  * n - function symbol version string to be applied
  34  * f - function prototype
  35  * p - full function symbol name
  36  */
  37
  38 /*
  39  * VERSION_SYMBOL
  40  * Creates a symbol version table entry binding symbol <b>@DPDK_<n> to the internal
  41  * function name <b>_<e>
  42  */
  43 #define VERSION_SYMBOL(b, e, n) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@DPDK_" RTE_STR(n))
  44
  45 /*
  46  * BIND_DEFAULT_SYMBOL
  47  * Creates a symbol version entry instructing the linker to bind references to
  48  * symbol <b> to the internal symbol <b>_<e>
  49  */
  50 #define BIND_DEFAULT_SYMBOL(b, e, n) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@@DPDK_" RTE_STR(n))
  51 #define __vsym __attribute__((used))
  52
  53 /*
  54  * MAP_STATIC_SYMBOL
  55  * If a function has been bifurcated into multiple versions, none of which
  56  * are defined as the exported symbol name in the map file, this macro can be
  57  * used to alias a specific version of the symbol to its exported name.  For
  58  * example, if you have 2 versions of a function foo_v1 and foo_v2, where the
  59  * former is mapped to foo@DPDK_1 and the latter is mapped to foo@DPDK_2 when
  60  * building a shared library, this macro can be used to map either foo_v1 or
  61  * foo_v2 to the symbol foo when building a static library, e.g.:
  62  * MAP_STATIC_SYMBOL(void foo(), foo_v2);
  63  */
  64 #define MAP_STATIC_SYMBOL(f, p)
  65
  66 #else
  67 /*
  68  * No symbol versioning in use
  69  */
  70 #define VERSION_SYMBOL(b, e, n)
  71 #define __vsym
  72 #define BIND_DEFAULT_SYMBOL(b, e, n)
  73 #define MAP_STATIC_SYMBOL(f, p) f __attribute__((alias(RTE_STR(p))))
  74 /*
  75  * RTE_BUILD_SHARED_LIB=n
  76  */
  77 #endif
  78
  79 #ifndef ALLOW_EXPERIMENTAL_API
  80
  81 #define __rte_experimental \
  82 __attribute__((deprecated("Symbol is not yet part of stable ABI"), \
  83 section(".text.experimental")))
  84
  85 #else
  86
  87 #define __rte_experimental \
  88 __attribute__((section(".text.experimental")))
  89
  90 #endif
  91
  92 #endif /* _RTE_COMPAT_H_ */