Hi,

The Policy Manual [1] gives the following recipe for supporting
parallel make:

ifneq (,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
NUMJOBS = $(patsubst parallel=%,%,$(filter parallel=%,$(DEB_BUILD_OPTIONS)))
MAKEFLAGS += -j$(NUMJOBS)
endif


Unfortunately, for packages that use recursive makefiles (the most
common practice) this results in the following warning

make[1]: warning: -jN forced in submake: disabling jobserver mode.

which apparently is sub-optimal [2]. The issue in that MAKEFLAGS
is applied to each recursive make. The recommended practice is to
supply -jN *only* to the initial invocation of make.

It strikes me, therefore, that the policy manual should be updated,
removing MAKEFLAGS and instead showing an explicit "make -J$(NUMJOBS) ...".

However, my problem is with cdbs: how can I supply -jN to only the
initial make?

Thanks,
-Steve


[1] http://www.debian.org/doc/debian-policy/ch-source.html#s-debianrules-options
[2] http://make.paulandlesley.org/jobserver.html

On Wed, Oct 15, 2008 at 07:17:41AM -0500, Steve M. Robbins wrote:
> It strikes me, therefore, that the policy manual should be updated,
> removing MAKEFLAGS and instead showing an explicit "make -J$(NUMJOBS) ...".

Or better "$(MAKE) -j$(NUMJOBS)".

> However, my problem is with cdbs: how can I supply -jN to only the
> initial make?

Maybe it's a ugly hack, but what about:

DEB_MAKE_BUILD_TARGET = -j$(NUMJOBS) ACTUAL_BUILD_TARGET

It should work at least in case you are using only the makefile.mk
class, I haven't checked if it can be made to work with autotools.mk.

Cheers.

--
Stefano Zacchiroli -*- PhD in Computer Science PostDoc @ Univ. Paris 7
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