Hi Emese, 2016-04-23 3:21 GMT+09:00 Emese Revfy <re.emese@xxxxxxxxx>: > Infrastructure for building independent shared library targets. > This effectively also reverts commit 62e2210798ed38928ab24841e8b4878a > (Masahiro Yamada, kbuild: drop shared library support from Makefile.host). > > Signed-off-by: Emese Revfy <re.emese@xxxxxxxxx> > --- > Documentation/kbuild/makefiles.txt | 39 ++++++++++++++++----- > scripts/Makefile.build | 2 +- > scripts/Makefile.clean | 3 +- > scripts/Makefile.host | 70 +++++++++++++++++++++++++++++++++++++- > 4 files changed, 103 insertions(+), 11 deletions(-) > > diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt > index 13f888a..250729b 100644 > --- a/Documentation/kbuild/makefiles.txt > +++ b/Documentation/kbuild/makefiles.txt > @@ -23,10 +23,11 @@ This document describes the Linux kernel Makefiles. > === 4 Host Program support > --- 4.1 Simple Host Program > --- 4.2 Composite Host Programs > - --- 4.3 Using C++ for host programs > - --- 4.4 Controlling compiler options for host programs > - --- 4.5 When host programs are actually built > - --- 4.6 Using hostprogs-$(CONFIG_FOO) > + --- 4.3 Defining shared libraries > + --- 4.4 Using C++ for host programs > + --- 4.5 Controlling compiler options for host programs > + --- 4.6 When host programs are actually built > + --- 4.7 Using hostprogs-$(CONFIG_FOO) > > === 5 Kbuild clean infrastructure > > @@ -643,7 +644,29 @@ Both possibilities are described in the following. > Finally, the two .o files are linked to the executable, lxdialog. > Note: The syntax <executable>-y is not permitted for host-programs. > > ---- 4.3 Using C++ for host programs > +--- 4.3 Defining shared libraries > + > + Objects with extension .so are considered shared libraries, and > + will be compiled as position independent objects. > + Kbuild provides support for shared libraries, but the usage > + shall be restricted. > + In the following example the libkconfig.so shared library is used > + to link the executable conf. > + > + Example: > + #scripts/kconfig/Makefile > + hostprogs-y := conf > + conf-objs := conf.o libkconfig.so > + libkconfig-objs := expr.o type.o Do you use this case? > + Shared libraries always require a corresponding -objs line, and > + in the example above the shared library libkconfig is composed by > + the two objects expr.o and type.o. > + expr.o and type.o will be built as position independent code and > + linked as a shared library libkconfig.so. C++ is not supported for > + shared libraries. You are supporting C++ shared libraries. Please do not revert as is, but change the comments to make sense. In the first place, I am wondering if we need to revive this documentation. What this commit is only interested in *.so generation, not host program support. > --- a/scripts/Makefile.build > +++ b/scripts/Makefile.build > @@ -60,7 +60,7 @@ endif > endif > > # Do not include host rules unless needed > -ifneq ($(hostprogs-y)$(hostprogs-m),) > +ifneq ($(hostprogs-y)$(hostprogs-m)$(hostlibs-y)$(hostlibs-m)$(hostcxxlibs-y)$(hostcxxlibs-m),) > include scripts/Makefile.host > endif > > diff --git a/scripts/Makefile.clean b/scripts/Makefile.clean > index 55c96cb..e4e88ab 100644 > --- a/scripts/Makefile.clean > +++ b/scripts/Makefile.clean > @@ -38,7 +38,8 @@ subdir-ymn := $(addprefix $(obj)/,$(subdir-ymn)) > __clean-files := $(extra-y) $(extra-m) $(extra-) \ > $(always) $(targets) $(clean-files) \ > $(host-progs) \ > - $(hostprogs-y) $(hostprogs-m) $(hostprogs-) > + $(hostprogs-y) $(hostprogs-m) $(hostprogs-) \ > + $(hostlibs-y) $(hostlibs-m) $(hostlibs-) $(hostcxxlibs-y)$(hostcxxlibs-m) is missing here. BTW, are you planning to support hostlibs without .so extention in the future? You are changing the top Makefile to clean with "*.so" pattern rule. Do you need to change both the top Makefile and Makefile.clean for belt-and-braces cleaning? > __clean-files := $(filter-out $(no-clean-files), $(__clean-files)) > > diff --git a/scripts/Makefile.host b/scripts/Makefile.host > index 133edfa..3439bd8 100644 > --- a/scripts/Makefile.host > +++ b/scripts/Makefile.host > @@ -20,7 +20,25 @@ > # Will compile qconf as a C++ program, and menu as a C program. > # They are linked as C++ code to the executable qconf > > +# hostprogs-y := conf > +# conf-objs := conf.o libkconfig.so > +# libkconfig-objs := expr.o type.o > +# Will create a shared library named libkconfig.so that consists of > +# expr.o and type.o (they are both compiled as C code and the object files > +# are made as position independent code). > +# conf.c is compiled as a C program, and conf.o is linked together with > +# libkconfig.so as the executable conf. > +# Note: Shared libraries consisting of C++ files are not supported Again, do you need to support "hostprogs-y" based on .so library? > +# hostcc-option > +# Usage: cflags-y += $(call hostcc-option,-march=winchip-c6,-march=i586) > + > +hostcc-option = $(call try-run,\ > + $(HOSTCC) $(HOSTCFLAGS) $(HOST_EXTRACFLAGS) $(1) -c -x c /dev/null -o "$$TMP",$(1),$(2)) > + > __hostprogs := $(sort $(hostprogs-y) $(hostprogs-m)) > +__hostlibs := $(sort $(hostlibs-y) $(hostlibs-m)) > +__hostcxxlibs := $(sort $(hostcxxlibs-y) $(hostcxxlibs-m)) > > # C code > # Executables compiled from a single .c file > @@ -42,6 +60,18 @@ host-cxxmulti := $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m))) > # C++ Object (.o) files compiled from .cc files > host-cxxobjs := $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs))) > > +# Shared libaries (only .c supported) > +# Shared libraries (.so) - all .so files referenced in "xxx-objs" > +host-cshlib := $(sort $(filter %.so, $(__hostlibs))) > +host-cxxshlib := $(sort $(filter %.so, $(__hostcxxlibs))) Do you use $(filter %.so, ...) on purpose? i.e. are you planning to support both hostlibs with/without .so? > +# Remove .so files from "xxx-objs" > +host-cobjs := $(filter-out %.so,$(host-cobjs)) > +host-cxxobjs := $(filter-out %.so,$(host-cxxobjs)) Why do you need to do this? > +# Object (.o) files used by the shared libaries > +host-cshobjs := $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs)))) > +host-cxxshobjs := $(sort $(foreach m,$(host-cxxshlib),$($(m:.so=-objs)))) > + > # output directory for programs/.o files > # hostprogs-y := tools/build may have been specified. > # Retrieve also directory of .o files from prog-objs or prog-cxxobjs notation > @@ -56,6 +86,10 @@ host-cmulti := $(addprefix $(obj)/,$(host-cmulti)) > host-cobjs := $(addprefix $(obj)/,$(host-cobjs)) > host-cxxmulti := $(addprefix $(obj)/,$(host-cxxmulti)) > host-cxxobjs := $(addprefix $(obj)/,$(host-cxxobjs)) > +host-cshlib := $(addprefix $(obj)/,$(host-cshlib)) > +host-cxxshlib := $(addprefix $(obj)/,$(host-cxxshlib)) > +host-cshobjs := $(addprefix $(obj)/,$(host-cshobjs)) > +host-cxxshobjs := $(addprefix $(obj)/,$(host-cxxshobjs)) > host-objdirs := $(addprefix $(obj)/,$(host-objdirs)) > > obj-dirs += $(host-objdirs) > @@ -124,5 +158,39 @@ quiet_cmd_host-cxxobjs = HOSTCXX $@ > $(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE > $(call if_changed_dep,host-cxxobjs) > > +# Compile .c file, create position independent .o file > +# host-cshobjs -> .o > +quiet_cmd_host-cshobjs = HOSTCC -fPIC $@ > + cmd_host-cshobjs = $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $< > +$(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE > + $(call if_changed_dep,host-cshobjs) > + > +# Compile .c file, create position independent .o file Please explain why c++ compiler should be used to compile .c files. This is not clear, so worth commenting. > +# host-cxxshobjs -> .o > +quiet_cmd_host-cxxshobjs = HOSTCXX -fPIC $@ > + cmd_host-cxxshobjs = $(HOSTCXX) $(hostcxx_flags) -fPIC -c -o $@ $< > +$(host-cxxshobjs): $(obj)/%.o: $(src)/%.c FORCE > + $(call if_changed_dep,host-cxxshobjs) > + > +# Link a shared library, based on position independent .o files > +# *.o -> .so shared library (host-cshlib) > +quiet_cmd_host-cshlib = HOSTLLD -shared $@ > + cmd_host-cshlib = $(HOSTCC) $(HOSTLDFLAGS) -shared -o $@ \ > + $(addprefix $(obj)/,$($(@F:.so=-objs))) \ > + $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F)) > +$(host-cshlib): FORCE > + $(call if_changed,host-cshlib) > +$(call multi_depend, $(host-cshlib), .so, -objs -cshobjs) should be $(call multi_depend, $(host-cshlib), .so, -objs) > +# Link a shared library, based on position independent .o files > +# *.o -> .so shared library (host-cxxshlib) > +quiet_cmd_host-cxxshlib = HOSTLLD -shared $@ > + cmd_host-cxxshlib = $(HOSTCXX) $(HOSTLDFLAGS) -shared -o $@ \ > + $(addprefix $(obj)/,$($(@F:.so=-objs))) \ > + $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F)) > +$(host-cxxshlib): FORCE > + $(call if_changed,host-cxxshlib) > +$(call multi_depend, $(host-cxxshlib), .so, -objs -cxxshobjs) should be $(call multi_depend, $(host-cxxshlib), .so, -objs) -- Best Regards Masahiro Yamada -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
