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strange struct declaration

Posted on 1999-01-19
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Last Modified: 2010-04-20
I recently found the following declaration in a program I'm studying:

static struct symbol_table my_symtab = {
         #include <linux/symtab_begin.h>
         X(printk),
        X(vmalloc),
        X(vfree),
        X(kerneld_send),
        X(current_set),
        X(sys_call_table),
        X(register_symtab_from),
        #include <linux/symtab_end.h>
};



I know the symbol_table struct is defined in module.h; but its contents seem to bear no resemblance to the above. Why does the declaration begin and end with the preprocessor instructions, and what exactly do symtab_begin.h and symtab_end.h do? (They're not on my system - Linux 2.0.0 slakware - at all.) Also, what does the X refer to? Is it some obscure preprocessor instruction? (It's not mentioned in Kernighan and Ritchie's book.)

Thanks for any help,

David
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Question by:sevrin
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5 Comments
 
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Expert Comment

by:ozo
ID: 1639176
Is X defined in linux/symtab_begin.h?
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Accepted Solution

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rbr earned 100 total points
ID: 1639177
Serach for a define X in your header files. The X must be a macro which is replaced by compile time with the structure component.
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Expert Comment

by:rbr
ID: 1639178
I found the define X in the
symtab_begin.h
#define X(sym) { _basic_version(sym) }

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Author Comment

by:sevrin
ID: 1639179
Ah, a macro. As I say, I don't have symtab_begin.h or symtab_end.h, so it was impossible for me to find out.

Thanks,

David
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LVL 10

Expert Comment

by:rbr
ID: 1639180
To ozo: Sorry I answered the question at the same time so I didn't see your comment.
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