[dpdk-dev] weak functions in some drivers

[dpdk-dev] weak functions in some drivers

[Damjan Marion (damarion)]

Hello,

We just spent few hours troubleshooting why vPMD is not working
in i40e driver. Conclusion was that problem is caused by linker 
linking the wrong instance of the i40e_rx_vec_dev_conf_condition_check(...).

That function is defined 2 times, once in i40e_rxtx.c and once in 
i40e_rxtx_vec.c. First one is defined as weak and it just returns -1.

librte_pmd_i40e.a contains both versions:

$ objdump -x librte_pmd_i40e.a| grep i40e_rx_vec_dev_conf_condition_check
0000000000006ca0  w    F .text	0000000000000006 i40e_rx_vec_dev_conf_condition_check
00000000000007c1 g     F .text.unlikely	000000000000001c i40e_rx_vec_dev_conf_condition_check

However when we are linking our app, linker was picking 1st (weak) one and vPMD init was failing.

Workaround we applied to get int working:  -Wl,--whole-archive <LIBS> -Wl,—no-whole-archive

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.

BTW Looks like same issue is happening with fm10k driver.

Thanks,

Damjan

Re: [dpdk-dev] weak functions in some drivers

[Ferruh Yigit]

Hi Damjan,

On 6/21/2016 4:01 PM, Damjan Marion (damarion) wrote:
> 
> Hello,
> 
> We just spent few hours troubleshooting why vPMD is not working
> in i40e driver. Conclusion was that problem is caused by linker 
> linking the wrong instance of the i40e_rx_vec_dev_conf_condition_check(...).
> 
> That function is defined 2 times, once in i40e_rxtx.c and once in 
> i40e_rxtx_vec.c. First one is defined as weak and it just returns -1.
> 
> librte_pmd_i40e.a contains both versions:
> 
> $ objdump -x librte_pmd_i40e.a| grep i40e_rx_vec_dev_conf_condition_check
> 0000000000006ca0  w    F .text	0000000000000006 i40e_rx_vec_dev_conf_condition_check
> 00000000000007c1 g     F .text.unlikely	000000000000001c i40e_rx_vec_dev_conf_condition_check
> 
> However when we are linking our app, linker was picking 1st (weak) one and vPMD init was failing.
App is linking with correct instance of the function for me, how can I
reproduce this linkage issue?

> 
> Workaround we applied to get int working:  -Wl,--whole-archive <LIBS> -Wl,—no-whole-archive
These flags already wraps PMD libraries, can you please give more detail
about workaround?

Thanks,
ferruh

Re: [dpdk-dev] weak functions in some drivers

[Damjan Marion (damarion)]

> On 21 Jun 2016, at 09:01, Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> 
> Hi Damjan,
> 
> On 6/21/2016 4:01 PM, Damjan Marion (damarion) wrote:
>> 
>> Hello,
>> 
>> We just spent few hours troubleshooting why vPMD is not working
>> in i40e driver. Conclusion was that problem is caused by linker 
>> linking the wrong instance of the i40e_rx_vec_dev_conf_condition_check(...).
>> 
>> That function is defined 2 times, once in i40e_rxtx.c and once in 
>> i40e_rxtx_vec.c. First one is defined as weak and it just returns -1.
>> 
>> librte_pmd_i40e.a contains both versions:
>> 
>> $ objdump -x librte_pmd_i40e.a| grep i40e_rx_vec_dev_conf_condition_check
>> 0000000000006ca0  w    F .text	0000000000000006 i40e_rx_vec_dev_conf_condition_check
>> 00000000000007c1 g     F .text.unlikely	000000000000001c i40e_rx_vec_dev_conf_condition_check
>> 
>> However when we are linking our app, linker was picking 1st (weak) one and vPMD init was failing.
> App is linking with correct instance of the function for me, how can I
> reproduce this linkage issue?
> 
>> 
>> Workaround we applied to get int working:  -Wl,--whole-archive <LIBS> -Wl,—no-whole-archive
> These flags already wraps PMD libraries, can you please give more detail
> about workaround?
> 

You can see our exact fix here:

https://git.fd.io/cgit/vpp/commit/?id=0977e4baabd97d1de711a3d7a0f285364a84159c

If you want to repro just pick the commit before this one…

Thanks,

Damjan

Re: [dpdk-dev] weak functions in some drivers

[Ferruh Yigit]

On 6/21/2016 4:01 PM, Damjan Marion (damarion) wrote:
> 
> Hello,
> 

...

> 
> 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 ...

> 
> BTW Looks like same issue is happening with fm10k driver.
> 

Re: [dpdk-dev] weak functions in some drivers

[Elo, Matias (Nokia - FI/Espoo)]

>> 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

Re: [dpdk-dev] weak functions in some drivers

[Sergio Gonzalez Monroy]

On 29/06/2016 14:26, 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

Re: [dpdk-dev] weak functions in some drivers

[Elo, Matias (Nokia - FI/Espoo)]

> >>> 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.

-Matias

Re: [dpdk-dev] weak functions in some drivers

[Elo, Matias (Nokia - FI/Espoo)]

> > >>> 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

Re: [dpdk-dev] weak functions in some drivers

[Sergio Gonzalez Monroy]

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?

Re: [dpdk-dev] weak functions in some drivers

[Elo, Matias (Nokia - FI/Espoo)]

> -----Original Message-----
> From: Sergio Gonzalez Monroy [mailto:sergio.gonzalez.monroy@intel.com]
> Sent: Friday, July 01, 2016 1:05 PM
> To: Elo, Matias (Nokia - FI/Espoo) <matias.elo@nokia-bell-labs.com>;
> dev@dpdk.org
> Cc: ferruh.yigit@intel.com; damarion@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

Re: [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@intel.com]
>> Sent: Friday, July 01, 2016 1:05 PM
>> To: Elo, Matias (Nokia - FI/Espoo) <matias.elo@nokia-bell-labs.com>;
>> dev@dpdk.org
>> Cc: ferruh.yigit@intel.com; damarion@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

Re: [dpdk-dev] weak functions in some drivers

[Zoltan Kiss]

Hi,

On 01/07/16 11:19, Sergio Gonzalez Monroy wrote:
> On 01/07/2016 11:16, Elo, Matias (Nokia - FI/Espoo) wrote:
>>> -----Original Message-----
>>> From: Sergio Gonzalez Monroy [mailto:sergio.gonzalez.monroy@intel.com]
>>> Sent: Friday, July 01, 2016 1:05 PM
>>> To: Elo, Matias (Nokia - FI/Espoo) <matias.elo@nokia-bell-labs.com>;
>>> dev@dpdk.org
>>> Cc: ferruh.yigit@intel.com; damarion@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

I've dug into this issue a bit, let me explain it with some example code:

main.c:
void bar(void);
void foo(void);

int main() {
	bar();
	//foo();
}
======================================
weak.c:
#include <stdio.h>

void __attribute__((weak)) foo(void) {
	printf("Weak\n");
}

void bar(void) {
	foo();
	printf("No call\n");
}
======================================
strong.c:
#include <stdio.h>

void foo(void) {
	printf("Strong\n");
}

Compile the second two into a library and link it with main:

gcc -o strong.o -c strong.c
ar rcs libbar.a strong.o weak.o
gcc main.c -L. -lbar -o main

Then look which foo were used:

objdump -x libbar.a | grep foo
0000000000000000 g     F .text	0000000000000010 foo
0000000000000000  w    F .text	0000000000000010 foo
0000000000000015 R_X86_64_PC32     foo-0x0000000000000004

objdump -x main | grep foo
0000000000400538 w F .text 0000000000000010 foo

So it got the weak version, simply because bar() was referred, and that 
already pulled the other symbols from that .o file, so ld stop looking 
for the another ones. If you uncomment the foo() call in main(), it will 
do a proper search, and pulls in the strong symbol.

I think there are only workarounds here:
- use --whole-archive, but that pulls in a lot of stuff you don't 
necessarily need. And if you feed that stuff to libtool, it seems to 
misbehave when it sees the -Wl parameter. The Ubuntu 14.04 libtool 
definitely has a bug around that. Matias ran into this with ODP-DPDK: it 
fixed the weak symbol problem in the .so, but then libtool forgot to add 
-ldpdk when doing statical linking
- use only dynamic linking: I guess that's not a viable restriction

The best would be to get rid of these weak functions, as they don't work 
the same with dynamic and static linking, especially the latter is 
problematic. I think Damjan suggested something like that in his 
original message.

I propose something like this:

@@ -3268,10 +3268,40 @@ i40e_set_tx_function(struct rte_eth_dev *dev)
  }

  /* Stubs needed for linkage when CONFIG_RTE_I40E_INC_VECTOR is set to 
'n' */
-int __attribute__((weak))
+int __attribute__((cold))
  i40e_rx_vec_dev_conf_condition_check(struct rte_eth_dev __rte_unused *dev)
  {
+#ifndef RTE_LIBRTE_I40E_INC_VECTOR
         return -1;
+#else
[stuff from the vector version]
+#endif /* (RTE_I40E_INC_VECTOR == n) */
  }


And then get rid of the vector version of this function. How about that?
And of course this applies to all weak functions.

Regards,

Zoltan