[yocto] why do numerous .bb files set "PARALLEL_MAKE"?

[Chris Larson]

On Fri, Nov 4, 2011 at 9:03 AM, Joshua Lock <josh at linux.intel.com> wrote:
> On 04/11/11 08:57, Robert P. J. Day wrote:
>>
>>   stumbled over this so i did a more thorough search:
>>
>> $ grep -w PARALLEL_MAKE $(find . -name *.bb)
>> ./meta/recipes-qt/qt-apps/qmmp_0.5.1.bb:PARALLEL_MAKE = ""
>> ./meta/recipes-core/eggdbus/eggdbus_0.6.bb:PARALLEL_MAKE = ""
>> ./meta/recipes-core/gettext/gettext_0.16.1.bb:PARALLEL_MAKE = ""
>> ./meta/recipes-core/gettext/gettext_0.18.1.1.bb:#PARALLEL_MAKE = ""
>> ./meta/recipes-bsp/pciutils/pciutils_3.1.7.bb:PARALLEL_MAKE = ""
>> ./meta/recipes-extended/sat-solver/sat-solver_git.bb:PARALLEL_MAKE=""
>> ./meta/recipes-extended/bash/bash_3.2.48.bb:PARALLEL_MAKE = ""
>> ./meta/recipes-extended/tcp-wrappers/tcp-wrappers_7.6.bb:PARALLEL_MAKE = ""
>> ./meta/recipes-extended/groff/groff_1.20.1.bb:PARALLEL_MAKE = ""
>> ... more snipped ...
>>
>>   why are individual recipes setting PARALLEL_MAKE to the empty
>> string?  it's a *build* option, why would it have any relevance to
>> individual .bb files?
>
> Because that individual BB file has problems being run with parallel
> make (make -j).

To clarify/elaborate a bit: the build system of the project that the
recipe is building doesn't support make -j (generally, this means
they're missing rules for dependencies, it's implicit, rather than
explicit). It's best to get these fixed upstream, where possible, but
we often just disable it to get it to work so we can move on. Feel
free to report these issues as bugs to the upstream projects, if
you're feeling motivated :)
-- 
Christopher Larson
clarson at kergoth dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Maintainer - Tslib
Senior Software Engineer, Mentor Graphics