Imported Upstream version 16.04

[deb_dpdk.git] / lib / librte_compat / rte_compat.h

diff --git a/lib/librte_compat/rte_compat.h b/lib/librte_compat/rte_compat.h
new file mode 100644 (file)
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+++ b/lib/librte_compat/rte_compat.h
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+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright(c) 2015 Neil Horman <nhorman@tuxdriver.com>.
+ *   All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _RTE_COMPAT_H_
+#define _RTE_COMPAT_H_
+#include <rte_common.h>
+
+#ifdef RTE_BUILD_SHARED_LIB
+
+/*
+ * Provides backwards compatibility when updating exported functions.
+ * When a symol is exported from a library to provide an API, it also provides a
+ * calling convention (ABI) that is embodied in its name, return type,
+ * arguments, etc.  On occasion that function may need to change to accommodate
+ * new functionality, behavior, etc.  When that occurs, it is desireable to
+ * allow for backwards compatibility for a time with older binaries that are
+ * dynamically linked to the dpdk.  To support that, the __vsym and
+ * VERSION_SYMBOL macros are created.  They, in conjunction with the
+ * <library>_version.map file for a given library allow for multiple versions of
+ * a symbol to exist in a shared library so that older binaries need not be
+ * immediately recompiled.
+ *
+ * Refer to the guidelines document in the docs subdirectory for details on the
+ * use of these macros
+ */
+
+/*
+ * Macro Parameters:
+ * b - function base name
+ * e - function version extension, to be concatenated with base name
+ * n - function symbol version string to be applied
+ * f - function prototype
+ * p - full function symbol name
+ */
+
+/*
+ * VERSION_SYMBOL
+ * Creates a symbol version table entry binding symbol <b>@DPDK_<n> to the internal
+ * function name <b>_<e>
+ */
+#define VERSION_SYMBOL(b, e, n) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@DPDK_" RTE_STR(n))
+
+/*
+ * BIND_DEFAULT_SYMBOL
+ * Creates a symbol version entry instructing the linker to bind references to
+ * symbol <b> to the internal symbol <b>_<e>
+ */
+#define BIND_DEFAULT_SYMBOL(b, e, n) __asm__(".symver " RTE_STR(b) RTE_STR(e) ", " RTE_STR(b) "@@DPDK_" RTE_STR(n))
+#define __vsym __attribute__((used))
+
+/*
+ * MAP_STATIC_SYMBOL
+ * If a function has been bifurcated into multiple versions, none of which
+ * are defined as the exported symbol name in the map file, this macro can be
+ * used to alias a specific version of the symbol to its exported name.  For
+ * example, if you have 2 versions of a function foo_v1 and foo_v2, where the
+ * former is mapped to foo@DPDK_1 and the latter is mapped to foo@DPDK_2 when
+ * building a shared library, this macro can be used to map either foo_v1 or
+ * foo_v2 to the symbol foo when building a static library, e.g.:
+ * MAP_STATIC_SYMBOL(void foo(), foo_v2);
+ */
+#define MAP_STATIC_SYMBOL(f, p)
+
+#else
+/*
+ * No symbol versioning in use
+ */
+#define VERSION_SYMBOL(b, e, n)
+#define __vsym
+#define BIND_DEFAULT_SYMBOL(b, e, n)
+#define MAP_STATIC_SYMBOL(f, p) f __attribute__((alias(RTE_STR(p))))
+/*
+ * RTE_BUILD_SHARED_LIB=n
+ */
+#endif
+
+
+#endif /* _RTE_COMPAT_H_ */