[Buildroot] [PATCH] packages: fix and improve support for top-level parallel makefile

Fabio Porcedda fabio.porcedda at gmail.com
Tue Apr 21 03:01:44 UTC 2015


On Mon, Apr 20, 2015 at 11:35 PM, Arnout Vandecappelle <arnout at mind.be> wrote:
> On 06/04/15 15:50, Fabio Porcedda wrote:
>> To fix packages that fail to build when PARALLEL_JOBS is empty instead
>> of using an empty PARALLEL_JOBS just avoid to using it in
>> the MAKE variable.
>>
>> Check the MAKEFLAGS variable to know automatically if the -j option is
>> being used, but use the "=" operator instead of the ":=" operator
>> because it can be checked only in a "recursively expanded variable".
>> Use "override" because otherwise it's impossible to change the
>> automatic variable "MAKE".
>>
>> Signed-off-by: Fabio Porcedda <fabio.porcedda at gmail.com>
>> ---
>>  Makefile            | 4 ++--
>>  package/Makefile.in | 3 ++-
>>  2 files changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 8d09725..6c2dcca 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -58,8 +58,8 @@ export HOSTARCH := $(shell uname -m | \
>>  #
>>  # Taking into account the above considerations, if you still want to execute
>>  # this top-level Makefile in parallel comment the ".NOTPARALLEL" line and
>> -# build using the following command:
>> -#    make BR2_JLEVEL= -j$((`getconf _NPROCESSORS_ONLN`+1))
>> +# use the -j<jobs> option when building, e.g:
>> +#      make -j$((`getconf _NPROCESSORS_ONLN`+1))
>>  .NOTPARALLEL:
>>
>>  # absolute path
>> diff --git a/package/Makefile.in b/package/Makefile.in
>> index fc57427..ed68e35 100644
>> --- a/package/Makefile.in
>> +++ b/package/Makefile.in
>> @@ -18,7 +18,8 @@ PARALLEL_JOBS := $(BR2_JLEVEL)
>>  endif
>>
>>  MAKE1 := $(HOSTMAKE) -j1
>> -MAKE := $(HOSTMAKE) $(if $(PARALLEL_JOBS),-j$(PARALLEL_JOBS))
>> +override MAKE = $(HOSTMAKE) \
>> +     $(if $(findstring j,$(filter-out --%,$(MAKEFLAGS))),,-j$(PARALLEL_JOBS))
>
>  Wouldn't it be much simpler to surround the definition of PARALLEL_JOBS at the
> beginning of this file with
>
> ifeq ($(findstring j,$(filter-out --%,$(MAKEFLAGS))),)
> ...
> endif
>
> ?

I don't know the reason but the MAKEFLAGS variable is empty if is
checked inside the "ifeq" directive, so the only way I've found to
check it is using the "$(if ,,)" function like what is done for the
QUIET variable.

Also some packages, like boost and jack2 use the $(PARALLEL_JOBS)
variable, if that variable isn't defined they fail to build.

In the first version of this patch set [1] I've modified those
packages in order to don't use the PARALLEL_JOBS if is empty, but as
Thomas P. suggested:

> In addition, even when top-level parallel build is used, using purely
> sequential build in each package may not be the good solution. Imagine
> you have a number of packages to build, and one of them is particularly
> long: if you don't build this package in parallel, the build time may
> be increased.

[1]:
http://patchwork.ozlabs.org/patch/457112/
http://patchwork.ozlabs.org/patch/455728/

Thanks for reviewing
-- 
Fabio Porcedda



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