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SubjectRe: [PATCH 5/6] module: make modversion_info contain a pointer, not an array.
On Thu, Jan 29, 2009 at 12:05:52AM +1030, Rusty Russell wrote:
> With allmodconfig (minus non-building modules) on 32-bit x86:
> Total size of modules before: 60009790 bytes
> Total size of modules after: 55927866 bytes
>
> Saving 7% of module size for CONFIG_MODVERSIONS=y; and these sections
> are kept resident as well.
>
> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
> ---
> include/linux/module.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/module.h b/include/linux/module.h
> --- a/include/linux/module.h
> +++ b/include/linux/module.h
> @@ -37,10 +37,12 @@ struct kernel_symbol
> const char *name;
> };
>
> +/* This is put in the __versions section of a module to indicate the version
> + * it expects for unknown symbols. */
> struct modversion_info
> {
> unsigned long crc;
> - char name[MODULE_NAME_LEN];
> + char *name;
> };

Hey Rusty thanks for the change, but I just got around to testing this
and I have a few observations/questions. First this breaks:

modprobe --dump-modversions foo.ko

I actually don't care, but just happened to stumble upon it when I also
noticed that your changes seemed to be working a little too well. I
currently happen to be building my modules out of order for example
module B depends on symbols from module A, but I build module B first.
This means that the exported symbols are not in the Module.symvers file
when module B is compiled. I would expect module B to fail to load yet
with your patches it magically works and I don't see any errors in the
logs. If I run:

objdump -s --section __versions B.ko

I only get something like:

Contents of section __versions:
0000 d782ec86 00000000

Of course if I build the modules in the correct order and dump the
__versions section I see the correct number of crc/char* pairs.

--
Shawn


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