Re: Fast LKM symbol resolution with SysV ELH hash table

[Greg KH <greg@kroah.com>]

On Tue, Oct 20, 2009 at 11:43:44PM -0600, Robert Hancock wrote:
> On 10/19/2009 09:02 AM, Carmelo Amoroso wrote:
>> 2009/10/19 Greg KH<greg@kroah.com>:
>>> On Mon, Oct 19, 2009 at 01:45:20PM +0200, Carmelo Amoroso wrote:
>>>> Just a few other notes. The current implementation I did based on SysV
>>>> has a drawback that is not backward compatible, so you cannot use old
>>>> modules with a kernel with the option enabled due to changes on struct
>>>> kernel_symbol.
>>>
>>> Why would this be a problem?  Whenever making a kernel config change,
>>> you should be able to rebuild everything, as lots of other configuration
>>> options are that way.
>>>
>>
>> This is not always true... there could be cases in which you cannot
>> recompile old modules
>> (e.g vendors that provide non GPL modules)
>
> Even non-GPL modules can normally be rebuilt as far as the module format is 
> concerned, there's usually an object file blob that gets compiled into a 
> module on install or something, like the Nvidia graphics driver. If 
> anyone's providing binary-only fully built modules (which would be 
> inherently tied to one exact kernel version and one configuration) they 
> really need to have their head examined..

Welcome to embedded Linux :)