Re: [dpdk-dev] [PATCH v3 1/5] mk: remove combined library and related options

["Gonzalez Monroy, Sergio" <sergio.gonzalez.monroy@intel.com>]

On 09/04/2015 21:34, Neil Horman wrote:
> On Thu, Apr 09, 2015 at 08:00:26PM +0300, Avi Kivity wrote:
>> On 04/09/2015 02:19 PM, Neil Horman wrote:
>>> On Thu, Apr 09, 2015 at 12:06:47PM +0300, Avi Kivity wrote:
>>>> On 04/09/2015 11:33 AM, Gonzalez Monroy, Sergio wrote:
>>>>> On 08/04/2015 19:26, Stephen Hemminger wrote:
>>>>>> On Wed,  8 Apr 2015 16:07:21 +0100
>>>>>> Sergio Gonzalez Monroy <sergio.gonzalez.monroy@intel.com> wrote:
>>>>>>
>>>>>>> Currently, the target/rules to build combined libraries is different
>>>>>>> than the one to build individual libraries.
>>>>>>>
>>>>>>> By removing the combined library option as a build configuration option
>>>>>>> we simplify the build pocess by having a single point for
>>>>>>> linking/archiving
>>>>>>> libraries in DPDK.
>>>>>>>
>>>>>>> This patch removes CONFIG_RTE_BUILD_COMBINE_LIB build config option and
>>>>>>> removes the makefiles associated with building a combined library.
>>>>>>>
>>>>>>> The CONFIG_RTE_LIBNAME config option is kept as it will be use to
>>>>>>> always generate a linker script that acts as a single combined library.
>>>>>>>
>>>>>>> Signed-off-by: Sergio Gonzalez Monroy
>>>>>>> <sergio.gonzalez.monroy@intel.com>
>>>>>> No. We use combined library and it greatly simplfies the application
>>>>>> linking process.
>>>>>>
>>>>> After all the opposition this patch had in v2, I did explain the current
>>>>> issues
>>>>> (see http://dpdk.org/ml/archives/dev/2015-March/015366.html ) and this was
>>>>> the agreed solution.
>>>>>
>>>>> As I mention in the cover letter (also see patch 2/5), building DPDK
>>>>> (after applying this patch series) will always generate a very simple
>>>>> linker script that behaves as a combined library.
>>>>> I encourage you to apply this patch series and try to build your app
>>>>> (which links against combined lib).
>>>>> Your app should build without problem unless I messed up somewhere and it
>>>>> needs fixing.
>>>> Is it possible to generate a pkgconfig file (dpdk.pc) that contains all of
>>>> the setting needed to compile and link with dpdk?  That will greatly
>>>> simplify usage.
>>>>
>>>> A linker script is just too esoteric.
>>>>
>>> Why esoteric?  We're not talking about a linker script in the sense of a binary
>>> layout file, we're talking about a prewritten/generated libdpdk_core.so that
>>> contains linker directives to include the appropriate libraries.  You link it
>>> just like you do any other library, but it lets you ignore how they are broken
>>> up.
>> You mean DT_NEEDED?  That's great, but it shouldn't be called a linker
>> script.
>>
> no, I don't mean DT_NEEDED, I mean a linker script, because thats what what
> sergio wrote is.
>
>>> We could certainly do a pkg-config file, but I don't think thats any more
>>> adventageous than this solution.
>> It solves more problems -- cflags etc.  Of course having the right DT_NEEDED
>> is a good thing regardless.
>>
> Thats a good point, pkgconfig doesn't provide that additionally.  Perhaps having
> both is the best solution.  As for the DT_NEEDED issues, the earlier threads
> ennumerated all the problems that were being found with the way the libraries
> were organized (circular dependencies).
>
> Neil
I am not entirely sure of the conclusion of this thread.

Are we happy with the current linker script solution as a replacement of 
the combined lib?
Do we want to provide pkg-config file in addition or instead of linker 
script?

I think I will split the series as there seems to be no objections to 
the patches related to DT_NEEDED entries.
I'll post a series for DT_NEEDED entries and another series for dealing 
with the combined lib (once we get to an agreement).

Does it sound reasonable?

Sergio