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

[Avi Kivity <avi@cloudius-systems.com>]

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.

> 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.