text: #ifndef _LINUX_EXPORT_H
  #define _LINUX_EXPORT_H
  
  /*
   * Export symbols from the kernel to modules.  Forked from module.h
   * to reduce the amount of pointless cruft we feed to gcc when only
   * exporting a simple symbol or two.
   *
   * Try not to add #includes here.  It slows compilation and makes kernel
   * hackers place grumpy comments in header files.
   */
  
  #define __VMLINUX_SYMBOL(x) x
  #define __VMLINUX_SYMBOL_STR(x) #x
  
  /* Indirect, so macros are expanded before pasting. */
  #define VMLINUX_SYMBOL(x) __VMLINUX_SYMBOL(x)
  #define VMLINUX_SYMBOL_STR(x) __VMLINUX_SYMBOL_STR(x)
  
  #ifndef __ASSEMBLY__
  struct kernel_symbol
  {
  	unsigned long value;
  	const char *name;
  };
  
  #ifdef MODULE
  extern struct module __this_module;
  #define THIS_MODULE (&__this_module)
  #else
  #define THIS_MODULE ((struct module *)0)
  #endif
  
  #ifdef CONFIG_MODULES
  
  #if defined(__KERNEL__) && !defined(__GENKSYMS__)
  #ifdef CONFIG_MODVERSIONS
  /* Mark the CRC weak since genksyms apparently decides not to
   * generate a checksums for some symbols */
  #if defined(CONFIG_MODULE_REL_CRCS)
  #define __CRC_SYMBOL(sym, sec)						\
  	asm("	.section \"___kcrctab" sec "+" #sym "\", \"a\"	\n"	\
  	    "	.weak	__crc_" #sym "				\n"	\
  	    "	.long	__crc_" #sym " - .			\n"	\
  	    "	.previous					\n");
  #else
  #define __CRC_SYMBOL(sym, sec)						\
  	asm("	.section \"___kcrctab" sec "+" #sym "\", \"a\"	\n"	\
  	    "	.weak	__crc_" #sym "				\n"	\
  	    "	.long	__crc_" #sym "				\n"	\
  	    "	.previous					\n");
  #endif
  #else
  #define __CRC_SYMBOL(sym, sec)
  #endif
  
  /* For every exported symbol, place a struct in the __ksymtab section */
  #define ___EXPORT_SYMBOL(sym, sec)					\
  	extern typeof(sym) sym;						\
  	__CRC_SYMBOL(sym, sec)						\
  	static const char __kstrtab_##sym[]				\
  	__attribute__((section("__ksymtab_strings"), aligned(1)))	\
  	= #sym;								\
  	static const struct kernel_symbol __ksymtab_##sym		\
  	__used								\
  	__attribute__((section("___ksymtab" sec "+" #sym), used))	\
  	= { (unsigned long)&sym, __kstrtab_##sym }
  
  #if defined(__KSYM_DEPS__)
  
  /*
   * For fine grained build dependencies, we want to tell the build system
   * about each possible exported symbol even if they're not actually exported.
   * We use a string pattern that is unlikely to be valid code that the build
   * system filters out from the preprocessor output (see ksym_dep_filter
   * in scripts/Kbuild.include).
   */
  #define __EXPORT_SYMBOL(sym, sec)	=== __KSYM_##sym ===
  
  #elif defined(CONFIG_TRIM_UNUSED_KSYMS)
  
  #include <generated/autoksyms.h>
  
  #define __EXPORT_SYMBOL(sym, sec)				\
  	__cond_export_sym(sym, sec, __is_defined(__KSYM_##sym))
  #define __cond_export_sym(sym, sec, conf)			\
  	___cond_export_sym(sym, sec, conf)
  #define ___cond_export_sym(sym, sec, enabled)			\
  	__cond_export_sym_##enabled(sym, sec)
  #define __cond_export_sym_1(sym, sec) ___EXPORT_SYMBOL(sym, sec)
  #define __cond_export_sym_0(sym, sec) /* nothing */
  
  #else
  #define __EXPORT_SYMBOL ___EXPORT_SYMBOL
  #endif
  
  #define EXPORT_SYMBOL(sym)					\
  	__EXPORT_SYMBOL(sym, "")
  
  #define EXPORT_SYMBOL_GPL(sym)					\
  	__EXPORT_SYMBOL(sym, "_gpl")
  
  #define EXPORT_SYMBOL_GPL_FUTURE(sym)				\
  	__EXPORT_SYMBOL(sym, "_gpl_future")
  
  #ifdef CONFIG_UNUSED_SYMBOLS
  #define EXPORT_UNUSED_SYMBOL(sym) __EXPORT_SYMBOL(sym, "_unused")
  #define EXPORT_UNUSED_SYMBOL_GPL(sym) __EXPORT_SYMBOL(sym, "_unused_gpl")
  #else
  #define EXPORT_UNUSED_SYMBOL(sym)
  #define EXPORT_UNUSED_SYMBOL_GPL(sym)
  #endif
  
  #endif	/* __GENKSYMS__ */
  
  #else /* !CONFIG_MODULES... */
  
  #define EXPORT_SYMBOL(sym)
  #define EXPORT_SYMBOL_GPL(sym)
  #define EXPORT_SYMBOL_GPL_FUTURE(sym)
  #define EXPORT_UNUSED_SYMBOL(sym)
  #define EXPORT_UNUSED_SYMBOL_GPL(sym)
  
  #endif /* CONFIG_MODULES */
  #endif /* !__ASSEMBLY__ */
  
  #endif /* _LINUX_EXPORT_H */
  