DPDK: Data Plane Development Kit

18.08.0-rc1
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_ */