[LEDE-DEV] What's the purpose / gain from using VARIANT?

[Florian Fainelli]

On 12/07/2016 11:52 AM, Rafał Miłecki wrote:
> On 12/07/2016 08:36 PM, Sergey Ryazanov wrote:
>> On Wed, Dec 7, 2016 at 10:10 PM, Rafał Miłecki <zajec5 at gmail.com> wrote:
>>> I'm aware some packages (e.g. upstream-ssl, hostapd, dnsmasq) use
>>> VARIANT.
>>>
>>> I don't really understand the gain of this. How does it differ from
>>> specifying separated packages?
>>> I'm looking at package/libs/ustream-ssl/Makefile and I don't see much
>>> code saving from using this VARIANT variable/feature.
>>> Looking at package/system/opkg/Makefile I can see BUILD_VARIANT is
>>> used for more specific CONFIGURE_ARGS. Is that where VARIANTS gets
>>> really helpful?
>>> Maybe I'm missing some real gain/value?
>>
>> IMHO VARIANT usage helps consolidate patches in single place. E.g. if
>> you would like change some common code in hostapd then just create a
>> new patch and VARIANT build two packages  (hostapd/wpa_supplicant)
>> from updated code. Without VARIANT you should duplicate your changes
>> (patch) in multiple places and keep them synchronized. So the gain is
>> simple: reducing of unproductive work.
> 
> I don't think sharing patches has anything to do with VARIANT. As long
> as you
> define packages in one Makefile they are going to share source (and so
> patches).

IMHO, this is more about sharing the build recipe more than anything
else. Usually building from one variant to another is just a matter of
tuning a bunch of build configuration parameters, but the bulk of how to
build a package remains the same.
-- 
Florian