[LEDE-DEV] Difference between AutoLoad vs. AutoProbe for kernel modules?

[John Crispin]

On 10/01/2017 09:17, Baptiste Jonglez wrote:
> On Tue, Jan 10, 2017 at 07:56:36AM +0100, John Crispin wrote:
>>>> While investigating an issue with module loading order¹, I discovered
>>>> that
>>>> some kernel packages use AutoProbe, like this:
>>>>
>>>>      AUTOLOAD:=$(call AutoProbe,xt_hashlimit)
>>>>
>>>> while some kernel packages use the AutoLoad helper I was used to, with a
>>>> priority:
>>>>
>>>>      AUTOLOAD:=$(call AutoLoad,28,raid0)
>>>>
>>>> Judging from this commit² and `include/kernel.mk`, it seems the only
>>>> difference is that AutoProbe does not include a priority.
>>>>
>>>> Is the loading order determined automatically for AutoProbe?  If so,
>>>> where
>>>> is the magic, and why is AutoLoad still needed in some cases?
>>>
>>> I opened the issue, so using autoload the modules will get a priority
>>> specified by the number, for wireguard above 90 would issue only one
>>> warning and using autoprobe the module would be loaded by the order of
>>> the name ? so setting the xt_hashlimit with a lower number (autoload)
>>> will start wireguard without complaining
>>>
>>
>> autoload is like insmod while autoproe is more liek modprobe. kmodloader
>> will first load all numbered modules in the given order and then probe
>> the remaining ones.
> 
> So, with AutoProbe, there is dependency resolution, similarly to modprobe?
> But without using depmod?
> 

correct. kmodloader will scan the ELF header and work out which other
modules are required to be loaded. depmod caches this dependency info
while kmodloader generates it when needed.

	John