[dpdk-dev] [PATCH v2] devtools: fix 32-bits build

[Ferruh Yigit]

On 11/9/2020 4:19 PM, Bruce Richardson wrote:
> On Mon, Nov 09, 2020 at 05:14:24PM +0100, Thomas Monjalon wrote:
>> 09/11/2020 16:44, Bruce Richardson:
>>> On Mon, Nov 09, 2020 at 04:28:16PM +0100, Thomas Monjalon wrote:
>>>> 09/11/2020 15:55, Ferruh Yigit:
>>>>> If the 'PKG_CONFIG_PATH' is set in the environment before script run,
>>>>> 32 bit still uses that value for 64-bits libraries.
>>>>>
>>>>>  From the build log:
>>>>>
>>>>> "
>>>>> Using DPDK_TARGET i386-pc-linux-gnu
>>>>> meson  -Dexamples=l3fwd --buildtype=debugoptimized --werror
>>>>> -Dc_args=-m32 -Dc_link_args=-m32
>>>>> /tmp/dpdk_maintain/self/dpdk/devtools/.. ./build-32b
>>>>> ...
>>>>> Using 'PKG_CONFIG_PATH' from environment with value:
>>>>> '/usr/local/lib64/pkgconfig/
>>>>> "
>>>>>
>>>>> This causes build error when linking with the found libraries.
>>>>>
>>>>> Reproduced with 'librte_bpf' which only has 64 bit installed but still
>>>>> enables building 'af_xdp' and link fails.
>>>>>
>>>>> To fix this, using default 'PKG_CONFIG_PATH' variable unless
>>>>> 'CUSTOM_PKG_CONFIG_PATH' set, and set the 'CUSTOM_PKG_CONFIG_PATH' for
>>>>> 32 bit build.
>>>>>
>>>>> Fixes: 9b83106d8784 ("devtools: test 32-bit build")
>>>>>
>>>>> Signed-off-by: Ferruh Yigit <ferruh.yigit at intel.com>
>>>>> ---
>>>>> Cc: Bruce Richardson <bruce.richardson at intel.com>
>>>>> Cc: Thomas Monjalon <thomas at monjalon.net>
>>>>>
>>>>> v2:
>>>>> * Enable overwriting default 'PKG_CONFIG_PATH' value
>>>>
>>>> It was not my conclusion.
>>>> I think we can just reset all env vars.
>>>>
>>>
>>> Perhaps, but I think that may cause more problems for people who want
>>> custom CFLAGS and LDFLAGS for building with extra 3rd-party packages.
>>> While this can be done using the config script that is sourced in, I
>>> suspect most of us do not use such a script.
>>>
>>>   Therefore I'd suggest rather than clearing the env vars globally, we just
>>> override them temporarily for the 32-bit, using CFLAGS32, LDFLAGS32,
>>> PKG_CONFIG_PATH32 instead. That allows someone to have a 32-bit and 64-bit
>>> version of e.g. libbpf installed, with a PKG_CONFIG_PATH pointing to each.
>>
>> So you want to duplicate all vars just to avoid writing them cleanly in a file?
>> And what happens for other targets?
>>
>> I'm tending to nack this approach.
>> There is no problem in using a clean config file.
>>
> Well, when you put it that way :-)
> However, I was only thinking of the 3 variables above, though really it's
> only the PKG_CONFIG_PATH that is going to be the most likely culprit, so
> supporting just one extra var "PKG_CONFIG_PATH_32" seems reasonable.
> 
> I'm also ok with your solution of just clearing the environment and relying
> on a config file too, though.
> 

I was worried for any side affects to reset the var, this is smaller change to 
change only 'CUSTOM_PKG_CONFIG_PATH' for 'build-32b'

I can send a new version to reset 'CUSTOM_PKG_CONFIG_PATH',
what is the intention/plan with the config file?