[dpdk-dev] weak functions in some drivers

[Sergio Gonzalez Monroy]

On 01/07/2016 11:16, Elo, Matias (Nokia - FI/Espoo) wrote:
>> -----Original Message-----
>> From: Sergio Gonzalez Monroy [mailto:sergio.gonzalez.monroy at intel.com]
>> Sent: Friday, July 01, 2016 1:05 PM
>> To: Elo, Matias (Nokia - FI/Espoo) <matias.elo at nokia-bell-labs.com>;
>> dev at dpdk.org
>> Cc: ferruh.yigit at intel.com; damarion at cisco.com
>> Subject: Re: [dpdk-dev] weak functions in some drivers
>>
>> On 01/07/2016 10:42, Elo, Matias (Nokia - FI/Espoo) wrote:
>>>>>>>> What is not clear to me is motivation to use weak here instead of simply
>>>>> using >CONFIG_RTE_I40E_INC_VECTOR
>>>>>>>> macro to exclude stubs in i40e_rxtx.c. It will make library smaller and
>> avoid
>>>>> issues like this one
>>>>>>>> which are quite hard to troubleshoot.
>>>>>>> Since this issue seen in fd.io, I didn't investigated more, but I don't
>>>>>>> want to clock your valid question, this is an attempt to resurrect the
>>>>>>> question ...
>>>>>> Hi,
>>>>>>
>>>>>> We are having exactly the same problem. For us the aforementioned
>>>>> workaround doesn't seem to work and vector mode is always disabled with
>> the
>>>>> i40e drivers. If I modify i40e_rxtx.c and exclude the stub functions using
>>>>> CONFIG_RTE_I40E_INC_VECTOR everything works as expected.
>>>>>> We are building DPDK with the CONFIG_RTE_BUILD_COMBINE_LIBS option
>>>>> enabled and link DPDK library to our application.
>>>>>> Any other ideas how this could be fixed?
>>>>>>
>>>>>> Regards,
>>>>>> Matias
>>>>>>
>>>>> So you have tried to link a combined static lib with --whole-archive
>>>>> -ldpdk --no-whole-archive and still get the wrong/weak function definition?
>>>>>
>>>>> Sergio
>>>> I actually just managed to fix the problem. In our case I had to add
>>>> '-Wl,--whole-archive,-ldpdk,--no-whole-archive'  to the end of AM_LDFLAGS.
>>>>
>>> It turned out that the problem actually wasn't fixed.
>>>
>>> DPDK is built with CONFIG_RTE_BUILD_COMBINE_LIBS=y and
>> EXTRA_CFLAGS="-fPIC"
>>> What we are linking originally:
>>> 	-l:libdpdk.a
>>>
>>> This works otherwise but vector mode i40e is not enabled.
>>>
>>> When trying:
>>> 	-Wl,--whole-archive,-l:libdpdk.a,--no-whole-archive
>>>
>>> Linking fails with ' undefined reference' errors to several dpdk functions
>> (rte_eal_init, rte_cpu_get_flag_enabled, rte_eth_stats_get...).
>>> Btw. there seems to be a Stack Overflow question related to this:
>> http://stackoverflow.com/questions/38064021/dpdk-include-libraries-in-dpdk-
>> application-compiled-as-shared-library
>>> -Matias
>> What DPDK version are you using?
> v16.04

Ok. I was asking because there is no CONFIG_RTE_BUILD_COMBINE_LIBS in 16.04.


Could you provide full link/compile command line? I'm not able to 
reproduce the issue so far