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authorMasahiro Yamada <masahiroy@kernel.org>2022-12-11 11:54:47 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2022-12-13 22:29:10 +0900
commit6768fa4bcb6c1618248f135d04b9287ba2724ae0 (patch)
tree0d49fcbba647b32e81d9da19192092dce67485e4
parenta5db80c65dbf9144de155f8a0f08becc9c307db0 (diff)
kbuild: add read-file macro
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@kernel.org> Reviewed-by: Nicolas Schier <nicolas@fjasle.eu> Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com> Tested-by: Alexander Lobakin <alexandr.lobakin@intel.com>
-rw-r--r--Makefile2
-rw-r--r--scripts/Kbuild.include14
-rw-r--r--scripts/Makefile.modfinal2
-rw-r--r--scripts/Makefile.modinst2
4 files changed, 17 insertions, 3 deletions
diff --git a/Makefile b/Makefile
index ff36288ae671..591485152a95 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 3be7c2d75667..21e76ba0de17 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.
@@ -62,6 +66,16 @@ 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 := :
quiet_kecho := echo
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal
index 4705d32388f3..83f2797e530c 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 := $(shell cat $(MODORDER))
+modules := $(call read-file, $(MODORDER))
__modfinal: $(modules)
@:
diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
index f4cff42069ad..65aac6be78ec 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 := $(shell cat $(MODORDER))
+modules := $(call read-file, $(MODORDER))
ifeq ($(KBUILD_EXTMOD),)
dst := $(MODLIB)/kernel