Re: [dpdk-dev] [PATCH v2] net/i40e: remove weak symbols

[Zoltan Kiss <zoltan.kiss@linaro.org>]

Hi,

I forgot to add the i40 maintainers as well. Would anyone like to weigh in?

Regards,

Zoltan

On 22/07/16 12:34, Zoltan Kiss wrote:
>
>
> On 21/07/16 19:58, bynes adam wrote:
>> On Wed, Jul 20, 2016 at 06:11:16PM +0100, Zoltan Kiss wrote:
>> Hi, Kiss
>>> Using weak symbols have a few issues with static linking:
>>>
>>> - normally the linker searches the .o files already linked, if your weak
>>>   one is there, it won't check if there is a strong version
>>> - unless the symbol is directly referred, but it's not the right
>>> thing to
>>>   rely on
>>> - or --whole-archive specified in the command line, which pulls in a lot
>>>   of unwanted stuff
>> --whole-archive on the other hand can ensure all the object files are
>> linked,
>> and the strong symbol will take precedence over weak symbol. So we
>> don't need to
>> take care of the sequence of the object files in the ar or between ar.
>
> --whole-archive is primarily for shared libraries, just as weak symbols.
> When people do static linking, their reason is often to avoid carrying
> around a big library while they only use a fraction of it.
>
>>> - whole-archive also makes libtool dropping the library from the command
>>>   line, which is what should happen with dynamic linking, but not with
>>>   static (observed on Ubuntu 14.04). This is an important bug if you
>>>   build a static library depending on DPDK
>> you mean the libtool bug for --whole-archive?
>> if it does, you shouldn't using the libtool,
>
> GNU libtool is a quite common tool for building libraries, it's a bit
> painful sometimes, but it works. What else do you recommend? I mean,
> something which is proven to be better?
>
>> BTW what's the circumstance you must use the libtool. using you own
>> makefile for
>> the library or APP.
>
> Building libraries which depend on DPDK
>
>>>
>>> This patch merges the two version and make the behaviour rely on the
>>> config.
>>>
>>> If we can agree in the concept, I can send a series to fix this for the
>>> other weak functions.
>>>
>>> Signed-off-by: Zoltan Kiss <zoltan.kiss@schaman.hu>
>>> ---
>>>
>>> Notes:
>>>     v2: fix commit message
>>>
>>>  drivers/net/i40e/i40e_rxtx.c     | 36
>>> +++++++++++++++++++++++++++++++++++-
>>>  drivers/net/i40e/i40e_rxtx_vec.c | 36
>>> ------------------------------------
>>>  2 files changed, 35 insertions(+), 37 deletions(-)
>>>
>> From the original design, we follow the rule, we don't want the Macro
>> in the file
>> to seperate the different Rx/Tx path for disabled/enabled vector
>> configuration.
>
> And why is it better to compile two versions of the same function when
> you already know at the time of compilation which one do you want to use?
>
>> Adam Bynes
>>