This patch adds some synax sugar for makefiles to simplify conditional linking cross-module glue objects into composite modules. For example: there two tristate config options MODULE_A and MODULE_B. Module-B wants to use some code from Module-A. Code of Module-A is available from Module-B if MODULE_A=y or if MODULE_A=m and MODULE_B=m. This patch allows to write this construction in makefile: obj-$(CONFIG_MODULE_A) += module_a.o obj-$(CONFIG_MODULE_B) += module_b.o module_b-y += core_b.o module_b-$(CONFIG_MODULE_A) += glue_a_b.o After that glue_a_b will be linked into module_b.o iff module-A is available. Objects from module_b-m will be linked only if CONFIG_MODULE_B=m. Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Michal Marek <mmarek@xxxxxxx> Cc: linux-kbuild@xxxxxxxxxxxxxxx --- Documentation/kbuild/makefiles.txt | 14 ++++++++++++++ scripts/Makefile.build | 16 ++++++++++++---- scripts/Makefile.lib | 8 ++++---- 3 files changed, 30 insertions(+), 8 deletions(-) diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 5198b74..dcdf424 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -224,6 +224,20 @@ more details, with real examples. kbuild will build an ext2.o file for you out of the individual parts and then link this into built-in.o, as you would expect. + Kbuild also includes objects listed in variable $(<module_name>-m) + if it builds composite objects as module (obj-m) and ignores them + for built-in modules (obj-y). This allows to implement flexible + dependence between two modules. + + Example: + obj-$(CONFIG_MODULE_A) += module_a.o + obj-$(CONFIG_MODULE_B) += module_b.o + module_b-y += core_b.o + module_b-$(CONFIG_MODULE_A) += glue_a_b.o + + In this example, glue_a_b.o will be used only if module_a is available + from module_b, this is true if CONFIG_MODULE_A=y or they both are =m. + --- 3.4 Objects which export symbols No special notation is required in the makefiles for diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 0e801c3..1c89dbf 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -421,16 +421,24 @@ endif # <composite-object>-objs := <list of .o files> # or # <composite-object>-y := <list of .o files> -link_multi_deps = \ +# or (for modules) +# <composite-object>-m := <list of .o files> +link_multi_deps-y = \ $(filter $(addprefix $(obj)/, \ $($(subst $(obj)/,,$(@:.o=-objs))) \ $($(subst $(obj)/,,$(@:.o=-y)))), $^) - + +link_multi_deps-m = \ +$(filter $(addprefix $(obj)/, \ +$($(subst $(obj)/,,$(@:.o=-objs))) \ +$($(subst $(obj)/,,$(@:.o=-y))) \ +$($(subst $(obj)/,,$(@:.o=-m)))), $^) + quiet_cmd_link_multi-y = LD $@ -cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis) +cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps-y) $(cmd_secanalysis) quiet_cmd_link_multi-m = LD [M] $@ -cmd_link_multi-m = $(cmd_link_multi-y) +cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps-m) $(cmd_secanalysis) # We would rather have a list of rules like # foo.o: $(foo-objs) diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 07125e6..b1ce3e4 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -48,14 +48,14 @@ subdir-ym := $(sort $(subdir-y) $(subdir-m)) # if $(foo-objs) exists, foo.o is a composite object multi-used-y := $(sort $(foreach m,$(obj-y), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))), $(m)))) -multi-used-m := $(sort $(foreach m,$(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))), $(m)))) +multi-used-m := $(sort $(foreach m,$(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m))), $(m)))) multi-used := $(multi-used-y) $(multi-used-m) single-used-m := $(sort $(filter-out $(multi-used-m),$(obj-m))) # Build list of the parts of our composite objects, our composite # objects depend on those (obviously) multi-objs-y := $(foreach m, $(multi-used-y), $($(m:.o=-objs)) $($(m:.o=-y))) -multi-objs-m := $(foreach m, $(multi-used-m), $($(m:.o=-objs)) $($(m:.o=-y))) +multi-objs-m := $(foreach m, $(multi-used-m), $($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m))) multi-objs := $(multi-objs-y) $(multi-objs-m) # $(subdir-obj-y) is the list of objects in $(obj-y) which uses dir/ to @@ -67,7 +67,7 @@ obj-dirs := $(dir $(multi-objs) $(subdir-obj-y)) # Replace multi-part objects by their individual parts, look at local dir only real-objs-y := $(foreach m, $(filter-out $(subdir-obj-y), $(obj-y)), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))),$($(m:.o=-objs)) $($(m:.o=-y)),$(m))) $(extra-y) -real-objs-m := $(foreach m, $(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y))),$($(m:.o=-objs)) $($(m:.o=-y)),$(m))) +real-objs-m := $(foreach m, $(obj-m), $(if $(strip $($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m))),$($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m)),$(m))) # Add subdir path @@ -163,7 +163,7 @@ dtc_cpp_flags = -Wp,-MD,$(depfile) -nostdinc \ # Finds the multi-part object the current object will be linked into modname-multi = $(sort $(foreach m,$(multi-used),\ - $(if $(filter $(subst $(obj)/,,$*.o), $($(m:.o=-objs)) $($(m:.o=-y))),$(m:.o=)))) + $(if $(filter $(subst $(obj)/,,$*.o), $($(m:.o=-objs)) $($(m:.o=-y)) $($(m:.o=-m))),$(m:.o=)))) ifdef REGENERATE_PARSERS -- 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
