Since GNU Make 4.2, $(file ...) supports the read operater '<', which is useful to read a file without forking a new process. No warning is shown even if the input file is missing. For older Make versions, it falls back to the cat command. Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> Reviewed-by: Nicolas Schier <nicolas@xxxxxxxxx> Reviewed-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx> Tested-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx> --- Changes in v3: - Check the MAKE_VERSION in an ad-hoc way Makefile | 2 +- scripts/Kbuild.include | 14 ++++++++++++++ scripts/Makefile.modfinal | 2 +- scripts/Makefile.modinst | 2 +- 4 files changed, 17 insertions(+), 3 deletions(-) diff --git a/Makefile b/Makefile index 8801cac4d3d5..2dda1e9a717a 100644 --- a/Makefile +++ b/Makefile @@ -376,7 +376,7 @@ 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 5019bc1e38e4..abdc269a51da 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. @@ -61,6 +65,16 @@ 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 +# +# Make 4.2 or later can read a file by using its builtin function. +ifneq ($(filter-out 3.% 4.0 4.1, $(MAKE_VERSION)),) +read-file = $(subst $(newline),$(space),$(file < $1)) +else +read-file = $(shell cat $1 2>/dev/null) +endif + ### # 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