Re: [PATCH v2] Makefile: libfdt: build only the strict necessary

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Claudio,

On 4/9/20 2:43 PM, Claudio Fontana wrote:
> when building dtc/libfdt, we were previously using dtc/Makefile,
> which tries to build some artifacts that are not needed,
> and can complain on stderr about the absence of tools that
> are not required to build just libfdt.
> 
> Instead, build only the strict necessary to get libfdt.a .
> 
> Remove the subdir-dtc "compatibility gunk" for recursion,
> since we are not recursing anymore.
> 
> Signed-off-by: Claudio Fontana <cfontana@suse.de>
> ---
>   Makefile  | 23 +++++++++++++----------
>   configure |  6 +-----
>   rules.mak |  2 ++
>   3 files changed, 16 insertions(+), 15 deletions(-)
> 
> v1 -> v2:
> 
> * fix error generated when running UNCHECKED_GOALS without prior configure,
>    for example during make docker-image-fedora. Without configure, DSOSUF is
>    empty, and the module pattern rule in rules.mak that uses this variable
>    can match too much; provide a default in the Makefile to avoid it.
> 
> * only attempt to build the archive when there is a non-empty list of objects.
>    This could be done in general for the %.a: pattern in rules.mak, but maybe
>    there are valid reasons to build an empty .a?
> 
> * removed some intermediate variables that did not add much value
>    (LIBFDT_srcdir, LIBFDT_archive)
> 
> Tested locally with 3 VPATH configurations (no-, VPATH, VPATH in src subdir),
> and with docker-image-fedora, docker-test-debug@fedora that failed before.
> 
> diff --git a/Makefile b/Makefile
> index 84ef881600..92bc853b5f 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -4,6 +4,10 @@ ifneq ($(words $(subst :, ,$(CURDIR))), 1)
>     $(error main directory cannot contain spaces nor colons)
>   endif
>   
> +# some pattern rules in rules.mak are confused by an empty DSOSUF,
> +# and UNCHECKED_GOALS for testing (docker-) can run without prior configure.
> +DSOSUF ?= ".so"
> +
>   # Always point to the root of the build tree (needs GNU make).
>   BUILD_DIR=$(CURDIR)
>   
> @@ -526,15 +530,16 @@ $(SOFTMMU_FUZZ_RULES): $(edk2-decompressed)
>   $(TARGET_DIRS_RULES):
>   	$(call quiet-command,$(MAKE) $(SUBDIR_MAKEFLAGS) -C $(dir $@) V="$(V)" TARGET_DIR="$(dir $@)" $(notdir $@),)
>   
> -DTC_MAKE_ARGS=-I$(SRC_PATH)/dtc VPATH=$(SRC_PATH)/dtc -C dtc V="$(V)" LIBFDT_srcdir=$(SRC_PATH)/dtc/libfdt
> -DTC_CFLAGS=$(CFLAGS) $(QEMU_CFLAGS)
> -DTC_CPPFLAGS=-I$(BUILD_DIR)/dtc -I$(SRC_PATH)/dtc -I$(SRC_PATH)/dtc/libfdt
> -
> -.PHONY: dtc/all
> -dtc/all: .git-submodule-status dtc/libfdt dtc/tests

I'm getting:

config-host.mak is out-of-date, running configure
make: *** No rule to make target 'dtc/all', needed by 'config-host.h'. 
Stop.

On second try it works.

Instead of alarming users, we could keep this target as a silent no-op, 
then remove it after some time.

For the rest, patch looks good, nice cleanup!

Regards,

Phil.

> -	$(call quiet-command,$(MAKE) $(DTC_MAKE_ARGS) CPPFLAGS="$(DTC_CPPFLAGS)" CFLAGS="$(DTC_CFLAGS)" LDFLAGS="$(QEMU_LDFLAGS)" ARFLAGS="$(ARFLAGS)" CC="$(CC)" AR="$(AR)" LD="$(LD)" $(SUBDIR_MAKEFLAGS) libfdt/libfdt.a,)
> +LIBFDT_objdir = dtc/libfdt
> +-include $(SRC_PATH)/dtc/libfdt/Makefile.libfdt
> +LIBFDT_objects = $(addprefix $(LIBFDT_objdir)/, $(LIBFDT_OBJS))
> +.PHONY: libfdt
> +libfdt: .git-submodule-status $(LIBFDT_objdir)/libfdt.a
> +$(LIBFDT_objdir)/libfdt.a: $(LIBFDT_objects)
> +	$(if $(LIBFDT_objects),$(call quiet-command,rm -f $@ && $(AR) rcs $@ $^,"AR","$(TARGET_DIR)$@"),)
>   
> -dtc/%: .git-submodule-status
> +$(LIBFDT_objects): | $(LIBFDT_objdir)
> +$(LIBFDT_objdir): .git-submodule-status
>   	@mkdir -p $@
>   
>   # Overriding CFLAGS causes us to lose defines added in the sub-makefile.
> @@ -563,7 +568,6 @@ slirp/all: .git-submodule-status
>   
>   # Compatibility gunk to keep make working across the rename of targets
>   # for recursion, to be removed some time after 4.1.
> -subdir-dtc: dtc/all
>   subdir-capstone: capstone/all
>   subdir-slirp: slirp/all
>   
> @@ -821,7 +825,6 @@ distclean: clean
>   	rm -rf $$d || exit 1 ; \
>           done
>   	rm -Rf .sdk
> -	if test -f dtc/version_gen.h; then $(MAKE) $(DTC_MAKE_ARGS) clean; fi
>   
>   KEYMAPS=da     en-gb  et  fr     fr-ch  is  lt  no  pt-br  sv \
>   ar      de     en-us  fi  fr-be  hr     it  lv  nl         pl  ru     th \
> diff --git a/configure b/configure
> index 233c671aaa..36f83ffc5a 100755
> --- a/configure
> +++ b/configure
> @@ -4278,10 +4278,6 @@ EOF
>         if test -d "${source_path}/dtc/libfdt" || test -e "${source_path}/.git" ; then
>             fdt=git
>             mkdir -p dtc
> -          if [ "$pwd_is_source_path" != "y" ] ; then
> -              symlink "$source_path/dtc/Makefile" "dtc/Makefile"
> -              symlink "$source_path/dtc/scripts" "dtc/scripts"
> -          fi
>             fdt_cflags="-I\$(SRC_PATH)/dtc/libfdt"
>             fdt_ldflags="-L\$(BUILD_DIR)/dtc/libfdt"
>             fdt_libs="$fdt_libs"
> @@ -8151,7 +8147,7 @@ echo "PIXMAN_CFLAGS=$pixman_cflags" >> $config_host_mak
>   echo "PIXMAN_LIBS=$pixman_libs" >> $config_host_mak
>   
>   if [ "$fdt" = "git" ]; then
> -  echo "config-host.h: dtc/all" >> $config_host_mak
> +  echo "config-host.h: libfdt" >> $config_host_mak
>   fi
>   if [ "$capstone" = "git" -o "$capstone" = "internal" ]; then
>     echo "config-host.h: capstone/all" >> $config_host_mak
> diff --git a/rules.mak b/rules.mak
> index 694865b63e..61eb474ba4 100644
> --- a/rules.mak
> +++ b/rules.mak
> @@ -105,6 +105,8 @@ LINK = $(call quiet-command, $(LINKPROG) $(CFLAGS) $(QEMU_LDFLAGS) -o $@ \
>   
>   DSO_OBJ_CFLAGS := -fPIC -DBUILD_DSO
>   module-common.o: CFLAGS += $(DSO_OBJ_CFLAGS)
> +
> +# Note: DSOSUF must not be empty, or these rules will try to match too much
>   %$(DSOSUF): QEMU_LDFLAGS += $(LDFLAGS_SHARED)
>   %$(DSOSUF): %.mo
>   	$(call LINK,$^)
>