[PATCH v8 2/3] modpost: Produce extended MODVERSIONS information

[Lucas De Marchi]

On Wed, Nov 06, 2024 at 02:19:38PM -0800, Matthew Maurer wrote:
>>
>> > If booted against an old kernel, it will
>> > behave as though there is no modversions information.
>>
>> Huh? This I don't get. If you have the new libkmod and boot
>> an old kernel, that should just not break becauase well, long
>> symbols were not ever supported properly anyway, so no regression.
>
>Specifically, if you set NO_BASIC_MODVERSIONS, build a module, and

how are you setting NO_BASIC_MODVERSIONS and loading it in a kernel
that still doesn't have that, i.e. before EXTENDED_MODVERSIONS?

Please Cc me on the format change and if possible submit the libkmod
support.

thanks
Lucas De Marchi

>then load said module with a kernel *before* EXTENDED_MODVERSIONS
>existed, it will see no modversion info on the module to check. This
>will be true regardless of symbol length.
>
>>
>> I'm not quite sure I understood your last comment here though,
>> can you clarify what you meant?
>>
>> Anyway, so now that this is all cleared up, the next question I have
>> is, let's compare a NO_BASIC_MODVERSIONS world now, given that the
>> userspace requirements aren't large at all, what actual benefits does
>> using this new extended mod versions have? Why wouldn't a distro end
>> up preferring this for say a future release for all modules?
>
>I think a distro will end up preferring using this for all modules,
>but was intending to put both in for a transitional period until the
>new format was more accepted.
>
>>
>>   Luis