Re: [dpdk-dev] [PATCH] mk: fix kernel modules build dependency

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 3/29/2018 5:43 PM, Thomas Monjalon wrote:
> 29/03/2018 18:38, Ferruh Yigit:
>> On 3/29/2018 5:32 PM, Thomas Monjalon wrote:
>>> 29/03/2018 17:48, Ferruh Yigit:
>>>> On 3/29/2018 4:39 PM, Thomas Monjalon wrote:
>>>>> Some kernel modules may need some header files to be "installed"
>>>>> in the build directory.
>>>>>
>>>>> When running multiple threads of make, kernel modules can try to
>>>>> be compiled before the lib headers are ready:
>>>>> 	make -j3
>>>>> 	kernel/linux/kni/kni_misc.c:19:37: fatal error:
>>>>> 		exec-env/rte_kni_common.h: No such file or directory
>>>>
>>>> Is there a reason to keep header in eal when module itself moved into kernel?
>>>
>>> It seems you missed my comment below:
>>>
>>> On a related note, this header file
>>>         lib/librte_eal/linuxapp/eal/include/exec-env/rte_kni_common.h
>>> could be moved to lib/librte_kni/
>>> Opinion?
>>
>> Ahh, yes we are saying same thing.
>> But not sure if it should go under lib/librte_kni/ or kernel/linux/kni/?
>> I lean to kernel/linux/kni/.
> 
> Why in kernel/?
> 
> Logically, kernel/ depends on lib/ but not the reverse.
> 
> And regarding the licensing, we avoid BSD files in Linux modules.

>From functionality point of view, module provides the functionality and it
should provide the header, this can be all subjective tough :)

Or in other words, if you have the kernel module, you can write another piece of
userspace application (without using librte_kni) and it will be functional.
But if you have the librte_kni only, it won't be functional on its own.

Providing header with kernel enables other userspace app to user KNI.