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SubjectRe: memcmp in modules
On 04/22/2013 07:26 AM, Tetsuo Handa wrote:
> Andy Shevchenko wrote:
>> What did I miss?
>
> Well, as of linux-next-20130422, memcmp() is not correctly exported to modules.
> Since linux-3.9-rc8 correctly exports memcmp(), this problem seems to be introduced
> in linux-next tree. Also, this problem seems to involve CONFIG_MODVERSIONS=y.
>
> [root@localhost linux-next]# modprobe ipv6
> FATAL: Error inserting ipv6 (/lib/modules/3.9.0-rc8-next-20130422/kernel/net/ipv6/ipv6.ko): Invalid argument
> [root@localhost linux-next]# dmesg
> ipv6: no symbol version for memcmp
> ipv6: Unknown symbol memcmp (err -22)
>
> Since arch/x86/include/asm/string_64.h uses
>
> int memcmp(const void *cs, const void *ct, size_t count);
>
> while arch/x86/include/asm/string_32.h uses
>
> #define memcmp __builtin_memcmp
>
> changing to what you have tried
>
> #define memcmp(a, b, n) __builtin_memcmp(a, b, n)
>
> or changing to what x86_64 does
>
> int memcmp(const void *cs, const void *ct, size_t count);
>
> might solve this problem. But I don't know which one is correct solution...
>

Rusty, this seems like a problem with your changes to the prefix
handling. Somehow memcmp being a macro gets picked up by some, but not
all, of the module-metadata generation tools.

Changing memcmp to a macro with arguments (see above) seems to paper
over the problem for this one, but there seems to be something much more
sinister going on and I would really like a good explanation as I fear
this can crop up in other places.

-hpa



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