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Commit 62e22107 authored by Masahiro Yamada's avatar Masahiro Yamada Committed by Michal Marek
Browse files

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: default avatarMasahiro Yamada <yamada.m@jp.panasonic.com>
Suggested-by: default avatarSam Ravnborg <sam@ravnborg.org>
Signed-off-by: default avatarMichal Marek <mmarek@suse.cz>
parent edb950c1

Documentation/kbuild/makefiles.txt

+8 −31
Original line number Diff line number Diff line
@@ -23,11 +23,10 @@ This document describes the Linux kernel Makefiles. 
	=== 4 Host Program support

	   --- 4.1 Simple Host Program

	   --- 4.2 Composite Host Programs

	   --- 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)

	   --- 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)



	=== 5 Kbuild clean infrastructure
@@ -643,29 +642,7 @@ 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 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



	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.



--- 4.4 Using C++ for host programs

--- 4.3 Using C++ for host programs



	kbuild offers support for host programs written in C++. This was

	introduced solely to support kconfig, and is not recommended
@@ -688,7 +665,7 @@ Both possibilities are described in the following. 
		qconf-cxxobjs := qconf.o

		qconf-objs    := check.o



--- 4.5 Controlling compiler options for host programs

--- 4.4 Controlling compiler options for host programs



	When compiling host programs, it is possible to set specific flags.

	The programs will always be compiled utilising $(HOSTCC) passed
@@ -716,7 +693,7 @@ Both possibilities are described in the following. 
	When linking qconf, it will be passed the extra option

	"-L$(QTDIR)/lib".



--- 4.6 When host programs are actually built

--- 4.5 When host programs are actually built



	Kbuild will only build host-programs when they are referenced

	as a prerequisite.
@@ -747,7 +724,7 @@ Both possibilities are described in the following. 
	This will tell kbuild to build lxdialog even if not referenced in

	any rule.



--- 4.7 Using hostprogs-$(CONFIG_FOO)

--- 4.6 Using hostprogs-$(CONFIG_FOO)



	A typical pattern in a Kbuild file looks like this:

scripts/Makefile.host

+3 −40
Original line number Diff line number Diff line
@@ -20,16 +20,6 @@ 
# 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



__hostprogs := $(sort $(hostprogs-y) $(hostprogs-m))



# C code
@@ -52,15 +42,6 @@ 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, $(host-cobjs)))

# Remove .so files from "xxx-objs"

host-cobjs	:= $(filter-out %.so,$(host-cobjs))



#Object (.o) files used by the shared libaries

host-cshobjs	:= $(sort $(foreach m,$(host-cshlib),$($(m:.so=-objs))))



# output directory for programs/.o files

# hostprogs-y := tools/build may have been specified. Retrieve directory

host-objdirs := $(foreach f,$(__hostprogs), $(if $(dir $(f)),$(dir $(f))))
@@ -82,8 +63,6 @@ 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-cshobjs	:= $(addprefix $(obj)/,$(host-cshobjs))

host-objdirs    := $(addprefix $(obj)/,$(host-objdirs))



obj-dirs += $(host-objdirs)
@@ -124,7 +103,7 @@ quiet_cmd_host-cmulti = HOSTLD $@ 
      cmd_host-cmulti	= $(HOSTCC) $(HOSTLDFLAGS) -o $@ \

			  $(addprefix $(obj)/,$($(@F)-objs)) \

			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))

$(host-cmulti): $(obj)/%: $(host-cobjs) $(host-cshlib) FORCE

$(host-cmulti): $(obj)/%: $(host-cobjs) FORCE

	$(call if_changed,host-cmulti)



# Create .o file from a single .c file
@@ -141,7 +120,7 @@ quiet_cmd_host-cxxmulti = HOSTLD $@ 
			  $(foreach o,objs cxxobjs,\

			  $(addprefix $(obj)/,$($(@F)-$(o)))) \

			  $(HOST_LOADLIBES) $(HOSTLOADLIBES_$(@F))

$(host-cxxmulti): $(obj)/%: $(host-cobjs) $(host-cxxobjs) $(host-cshlib) FORCE

$(host-cxxmulti): $(obj)/%: $(host-cobjs) $(host-cxxobjs) FORCE

	$(call if_changed,host-cxxmulti)



# Create .o file from a single .cc (C++) file
@@ -150,21 +129,5 @@ 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)



# 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): $(obj)/%: $(host-cshobjs) FORCE

	$(call if_changed,host-cshlib)



targets += $(host-csingle)  $(host-cmulti) $(host-cobjs)\

	   $(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs)
 
	   $(host-cxxmulti) $(host-cxxobjs)