On Wed, Jul 23, 2014 at 9:10 PM, Hongxu Jia <hongxu....@windriver.com> wrote: > 1. How to reproduce the issue: > > 1) manually modify gcc/Makefile.in to delay the generation of config.h: > ... > diff --git gcc-4.9.0/gcc/Makefile.in gcc-4.9.0/gcc/Makefile.in > --- gcc-4.9.0/gcc/Makefile.in > +++ gcc-4.9.0/gcc/Makefile.in > @@ -1622,9 +1622,12 @@ tm.h: cs-tm.h ; @true > tm_p.h: cs-tm_p.h ; @true > > cs-config.h: Makefile > + @echo "start to generate config.h `date`" > + sleep 10 > TARGET_CPU_DEFAULT="" \ > HEADERS="$(host_xm_include_list)" DEFINES="$(host_xm_defines)" \ > $(SHELL) $(srcdir)/mkconfig.sh config.h > + @echo "config.h generated `date`" > > cs-bconfig.h: Makefile > TARGET_CPU_DEFAULT="" \ > ... > > 2) compiling gcc > > 2. Analysis > > Most C source files included config.h which was generated by a rule. > But no related prerequisites was added to the C source compiling rule. > There was potential building failure while makefile enabled parallel.
Why not update the dependencies instead of this hack? For 4.10/5.0 is this already fixed by changing how dependencies work. Thanks, Andrew > > The C source compiling rule used suffix rule '.c.o', but the suffix > rule doesn't support prerequisites. > https://www.gnu.org/software/make/manual/html_node/Suffix-Rules.html > > We used the pattern rule '%.o : %.c' to instead, and add the config.h > as its prerequisite > > We also moved the '%.o : %.c' rule down to the 'build/%.o :' rule, which > makes '%.o : %.c' rule doesn't override 'build/%.o :'. > > For more detail: > https://bugzilla.yoctoproject.org/show_bug.cgi?id=6568 > > Signed-off-by: Hongxu Jia <hongxu....@windriver.com> > --- > gcc/Makefile.in | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git gcc-4.9.0/gcc/Makefile.in gcc-4.9.0/gcc/Makefile.in > index 6475cba..04889fe 100644 > --- gcc-4.9.0/gcc/Makefile.in > +++ gcc-4.9.0/gcc/Makefile.in > @@ -1054,10 +1054,6 @@ COMPILE = source='$<' object='$@' libtool=no \ > POSTCOMPILE = > endif > > -.cc.o .c.o: > - $(COMPILE) $< > - $(POSTCOMPILE) > - > # > # Support for additional languages (other than C). > # C can be supported this way too (leave for later). > @@ -2342,6 +2338,14 @@ build/%.o : # dependencies provided by explicit rule > later > $(COMPILER_FOR_BUILD) -c $(BUILD_COMPILERFLAGS) $(BUILD_CPPFLAGS) \ > -o $@ $< > > +%.o: %.c $(CONFIG_H) > + $(COMPILE) $< > + $(POSTCOMPILE) > + > +%.o: %.cc $(CONFIG_H) > + $(COMPILE) $< > + $(POSTCOMPILE) > + > ## build/version.o is compiled by the $(COMPILER_FOR_BUILD) but needs > ## several C macro definitions, just like version.o > build/version.o: version.c version.h \ > -- > 1.8.1.2 >
