From: Masahiro Yamada <masahiroy@xxxxxxxxxx> Date: Sun, 27 Nov 2022 07:56:22 +0900 > Since GNU Make 4.2, $(file ...) supports the read operater '<', which > is useful to read a file without forking any process. No warning is > shown even if the input file is missing. > > For older Make versions, it falls back to the cat command. > > The added ifeq will break when GNU Make 4.10 or 10.0 is released. > It will take a long time if the current release pace continues. > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > Reviewed-by: Nicolas Schier <nicolas@xxxxxxxxx> > --- > > (no changes since v1) > > Makefile | 2 +- > scripts/Kbuild.include | 15 +++++++++++++++ > scripts/Makefile.modfinal | 2 +- > scripts/Makefile.modinst | 2 +- > 4 files changed, 18 insertions(+), 3 deletions(-) > > diff --git a/Makefile b/Makefile > index eb80332f7b51..60ce9dcafc72 100644 > --- a/Makefile > +++ b/Makefile > @@ -369,7 +369,7 @@ else # !mixed-build > include $(srctree)/scripts/Kbuild.include > > # Read KERNELRELEASE from include/config/kernel.release (if it exists) > -KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null) > +KERNELRELEASE = $(call read-file, include/config/kernel.release) > KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION) > export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION > > diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include > index 4b8cf464b53b..55c2243f91c8 100644 > --- a/scripts/Kbuild.include > +++ b/scripts/Kbuild.include > @@ -10,6 +10,10 @@ empty := > space := $(empty) $(empty) > space_escape := _-_SPACE_-_ > pound := \# > +define newline > + > + > +endef > > ### > # Comparison macros. > @@ -55,6 +59,17 @@ stringify = $(squote)$(quote)$1$(quote)$(squote) > kbuild-dir = $(if $(filter /%,$(src)),$(src),$(srctree)/$(src)) > kbuild-file = $(or $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Makefile) > > +### > +# Read a file, replacing newlines with spaces > +# > +# This ifeq will break when GNU Make 4.10 is released. > +# Remove this conditional until then. > +ifeq ($(call test-ge, $(MAKE_VERSION), 4.2),y) > +read-file = $(subst $(newline),$(space),$(file < $1)) > +else > +read-file = $(shell cat $1 2>/dev/null) > +endif > + Great stuff. Used it in my upcoming series to simplify things, works as expected. sed-syms = $(subst $(space),\|,$(foreach file,$(sym-files-y),$(call read-file,$(file)))) The only thing that came to my mind while I was implementing the oneliner above: maybe add ability to read multiple files? For now, I used a foreach, could it be somehow incorporated into read-file already? Besides that: Reviewed-and-tested-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx> > ### > # Easy method for doing a status message > kecho := : > diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal > index 25bedd83644b..7252f6cf7837 100644 > --- a/scripts/Makefile.modfinal > +++ b/scripts/Makefile.modfinal > @@ -13,7 +13,7 @@ include $(srctree)/scripts/Kbuild.include > include $(srctree)/scripts/Makefile.lib > > # find all modules listed in modules.order > -modules := $(sort $(shell cat $(MODORDER))) > +modules := $(sort $(call read-file, $(MODORDER))) > > __modfinal: $(modules) > @: > diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst > index a4c987c23750..509d424dbbd2 100644 > --- a/scripts/Makefile.modinst > +++ b/scripts/Makefile.modinst > @@ -9,7 +9,7 @@ __modinst: > include include/config/auto.conf > include $(srctree)/scripts/Kbuild.include > > -modules := $(sort $(shell cat $(MODORDER))) > +modules := $(sort $(call read-file, $(MODORDER))) > > ifeq ($(KBUILD_EXTMOD),) > dst := $(MODLIB)/kernel > -- > 2.34.1 Thanks, Olek
