kbuild: drop shared library support from Makefile.host
The shared library feature in Makefile.host is no longer used. Rip it off to keep the build infrastucture simple. Update Documentation/kbuild/makefiles.txt too. The section "4.3 Definition shared libraries" should be removed and the following sections should be re-numbered. Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com> Suggested-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Michal Marek <mmarek@suse.cz>
This commit is contained in:
Masahiro Yamada
Michal Marek
parent
edb950c17d
commit
62e2210798
@ -23,11 +23,10 @@ This document describes the Linux kernel Makefiles.
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=== 4 Host Program support
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--- 4.1 Simple Host Program
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--- 4.2 Composite Host Programs
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--- 4.3 Defining shared libraries
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--- 4.4 Using C++ for host programs
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--- 4.5 Controlling compiler options for host programs
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--- 4.6 When host programs are actually built
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--- 4.7 Using hostprogs-$(CONFIG_FOO)
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--- 4.3 Using C++ for host programs
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--- 4.4 Controlling compiler options for host programs
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--- 4.5 When host programs are actually built
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--- 4.6 Using hostprogs-$(CONFIG_FOO)
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=== 5 Kbuild clean infrastructure
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@ -643,29 +642,7 @@ Both possibilities are described in the following.
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Finally, the two .o files are linked to the executable, lxdialog.
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Note: The syntax <executable>-y is not permitted for host-programs.
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--- 4.3 Defining shared libraries
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Objects with extension .so are considered shared libraries, and
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will be compiled as position independent objects.
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Kbuild provides support for shared libraries, but the usage
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shall be restricted.
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In the following example the libkconfig.so shared library is used
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to link the executable conf.
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Example:
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#scripts/kconfig/Makefile
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hostprogs-y := conf
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conf-objs := conf.o libkconfig.so
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libkconfig-objs := expr.o type.o
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Shared libraries always require a corresponding -objs line, and
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in the example above the shared library libkconfig is composed by
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the two objects expr.o and type.o.
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expr.o and type.o will be built as position independent code and
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linked as a shared library libkconfig.so. C++ is not supported for
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shared libraries.
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--- 4.4 Using C++ for host programs
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--- 4.3 Using C++ for host programs
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kbuild offers support for host programs written in C++. This was
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introduced solely to support kconfig, and is not recommended
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@ -688,7 +665,7 @@ Both possibilities are described in the following.
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qconf-cxxobjs := qconf.o
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qconf-objs := check.o
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--- 4.5 Controlling compiler options for host programs
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--- 4.4 Controlling compiler options for host programs
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When compiling host programs, it is possible to set specific flags.
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The programs will always be compiled utilising $(HOSTCC) passed
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@ -716,7 +693,7 @@ Both possibilities are described in the following.
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When linking qconf, it will be passed the extra option
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"-L$(QTDIR)/lib".
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--- 4.6 When host programs are actually built
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--- 4.5 When host programs are actually built
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Kbuild will only build host-programs when they are referenced
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as a prerequisite.
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@ -747,7 +724,7 @@ Both possibilities are described in the following.
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This will tell kbuild to build lxdialog even if not referenced in
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any rule.
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--- 4.7 Using hostprogs-$(CONFIG_FOO)
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--- 4.6 Using hostprogs-$(CONFIG_FOO)
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A typical pattern in a Kbuild file looks like this:
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@ -20,16 +20,6 @@
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# Will compile qconf as a C++ program, and menu as a C program.
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# They are linked as C++ code to the executable qconf
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# hostprogs-y := conf
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# conf-objs := conf.o libkconfig.so
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# libkconfig-objs := expr.o type.o
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# Will create a shared library named libkconfig.so that consists of
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# expr.o and type.o (they are both compiled as C code and the object files
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# are made as position independent code).
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# conf.c is compiled as a C program, and conf.o is linked together with
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# libkconfig.so as the executable conf.
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# Note: Shared libraries consisting of C++ files are not supported
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__hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))
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# C code
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@ -52,15 +42,6 @@ host-cxxmulti := $(foreach m,$(__hostprogs),$(if $($(m)-cxxobjs),$(m)))
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# C++ Object (.o) files compiled from .cc files
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host-cxxobjs := $(sort $(foreach m,$(host-cxxmulti),$($(m)-cxxobjs)))
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# Shared libaries (only .c supported)
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# Shared libraries (.so) - all .so files referenced in "xxx-objs"
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host-cshlib := $(sort $(filter %.so, $(host-cobjs)))
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# Remove .so files from "xxx-objs"
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host-cobjs := $(filter-out %.so,$(host-cobjs))
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#Object (.o) files used by the shared libaries
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host-cshobjs := $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))
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# output directory for programs/.o files
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# hostprogs-y := tools/build may have been specified. Retrieve directory
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host-objdirs := $(foreach f,$(__hostprogs), $(if $(dir $(f)),$(dir $(f))))
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@ -82,8 +63,6 @@ host-cmulti := $(addprefix $(obj)/,$(host-cmulti))
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host-cobjs := $(addprefix $(obj)/,$(host-cobjs))
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host-cxxmulti := $(addprefix $(obj)/,$(host-cxxmulti))
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host-cxxobjs := $(addprefix $(obj)/,$(host-cxxobjs))
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host-cshlib := $(addprefix $(obj)/,$(host-cshlib))
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host-cshobjs := $(addprefix $(obj)/,$(host-cshobjs))
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host-objdirs := $(addprefix $(obj)/,$(host-objdirs))
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obj-dirs += $(host-objdirs)
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@ -124,7 +103,7 @@ quiet_cmd_host-cmulti = HOSTLD $@
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cmd_host-cmulti = $(HOSTCC) $(HOSTLDFLAGS) -o $@ \
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$(addprefix $(obj)/,$($(@F)-objs)) \
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$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
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$(host-cmulti): $(obj)/%: $(host-cobjs) $(host-cshlib) FORCE
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$(host-cmulti): $(obj)/%: $(host-cobjs) FORCE
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$(call if_changed,host-cmulti)
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# Create .o file from a single .c file
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@ -141,7 +120,7 @@ quiet_cmd_host-cxxmulti = HOSTLD $@
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$(foreach o,objs cxxobjs,\
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$(addprefix $(obj)/,$($(@F)-$(o)))) \
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$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
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$(host-cxxmulti): $(obj)/%: $(host-cobjs) $(host-cxxobjs) $(host-cshlib) FORCE
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$(host-cxxmulti): $(obj)/%: $(host-cobjs) $(host-cxxobjs) FORCE
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$(call if_changed,host-cxxmulti)
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# Create .o file from a single .cc (C++) file
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@ -150,21 +129,5 @@ quiet_cmd_host-cxxobjs = HOSTCXX $@
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$(host-cxxobjs): $(obj)/%.o: $(src)/%.cc FORCE
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$(call if_changed_dep,host-cxxobjs)
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# Compile .c file, create position independent .o file
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# host-cshobjs -> .o
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quiet_cmd_host-cshobjs = HOSTCC -fPIC $@
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cmd_host-cshobjs = $(HOSTCC) $(hostc_flags) -fPIC -c -o $@ $<
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$(host-cshobjs): $(obj)/%.o: $(src)/%.c FORCE
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$(call if_changed_dep,host-cshobjs)
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# Link a shared library, based on position independent .o files
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# *.o -> .so shared library (host-cshlib)
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quiet_cmd_host-cshlib = HOSTLLD -shared $@
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cmd_host-cshlib = $(HOSTCC) $(HOSTLDFLAGS) -shared -o $@ \
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$(addprefix $(obj)/,$($(@F:.so=-objs))) \
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$(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))
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$(host-cshlib): $(obj)/%: $(host-cshobjs) FORCE
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$(call if_changed,host-cshlib)
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targets += $(host-csingle) $(host-cmulti) $(host-cobjs)\
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$(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs)
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$(host-cxxmulti) $(host-cxxobjs)
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