kbuild: use $(abspath ...) instead of $(shell cd ... && /bin/pwd)

Kbuild conventionally uses $(shell cd ... && /bin/pwd) idiom to get
the absolute path of the directory because GNU Make 3.80, the minimal
supported version at that time, did not support $(abspath ...) or
$(realpath ...).

Commit 37d69ee30808 ("docs: bump minimal GNU Make version to 3.81")
dropped the GNU Make 3.80 support, so we are now allowed to use those
make-builtin helpers.

This conversion will provide better portability without relying on
the pwd command or its location /bin/pwd.

I am intentionally using $(realpath ...) instead $(abspath ...) in
some places.  The difference between the two is $(realpath ...)
returns an empty string if the given path does not exist.  It is
convenient in places where we need to error-out if the makefile fails
to create an output directory.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Thierry Reding <treding@nvidia.com>

diff --git a/Makefile b/Makefile
index 6eba23bcb5ad031d6365d938984dd3140a596018..eca6cffa3cd7f7ddcd3c0f689e3bab76bb519ab1 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -130,8 +130,8 @@ endif
 ifneq ($(KBUILD_OUTPUT),)
 # check that the output directory actually exists
 saved-output := $(KBUILD_OUTPUT)
-KBUILD_OUTPUT := $(shell mkdir -p $(KBUILD_OUTPUT) && cd $(KBUILD_OUTPUT) \
-                                                               && /bin/pwd)
+$(shell [ -d $(KBUILD_OUTPUT) ] || mkdir -p $(KBUILD_OUTPUT))
+KBUILD_OUTPUT := $(realpath $(KBUILD_OUTPUT))
 $(if $(KBUILD_OUTPUT),, \
      $(error failed to create output directory "$(saved-output)"))
 
@@ -978,7 +978,7 @@ ifdef CONFIG_HEADERS_CHECK
        $(Q)$(MAKE) -f $(srctree)/Makefile headers_check
 endif
 ifdef CONFIG_GDB_SCRIPTS
-       $(Q)ln -fsn `cd $(srctree) && /bin/pwd`/scripts/gdb/vmlinux-gdb.py
+       $(Q)ln -fsn $(abspath $(srctree)/scripts/gdb/vmlinux-gdb.py)
 endif
 ifdef CONFIG_TRIM_UNUSED_KSYMS
        $(Q)$(CONFIG_SHELL) $(srctree)/scripts/adjust_autoksyms.sh \
@@ -1237,7 +1237,7 @@ _modinst_:
        @rm -rf $(MODLIB)/kernel
        @rm -f $(MODLIB)/source
        @mkdir -p $(MODLIB)/kernel
-       @ln -s `cd $(srctree) && /bin/pwd` $(MODLIB)/source
+       @ln -s $(abspath $(srctree)) $(MODLIB)/source
        @if [ ! $(objtree) -ef  $(MODLIB)/build ]; then \
                rm -f $(MODLIB)/build ; \
                ln -s $(CURDIR) $(MODLIB)/build ; \
@@ -1629,11 +1629,11 @@ image_name:
 # Clear a bunch of variables before executing the submake
 tools/: FORCE
        $(Q)mkdir -p $(objtree)/tools
-       $(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(shell cd $(objtree) && /bin/pwd) subdir=tools -C $(src)/tools/
+       $(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(src)/tools/
 
 tools/%: FORCE
        $(Q)mkdir -p $(objtree)/tools
-       $(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(shell cd $(objtree) && /bin/pwd) subdir=tools -C $(src)/tools/ $*
+       $(Q)$(MAKE) LDFLAGS= MAKEFLAGS="$(tools_silent) $(filter --j% -j,$(MAKEFLAGS))" O=$(abspath $(objtree)) subdir=tools -C $(src)/tools/ $*
 
 # Single targets
 # ---------------------------------------------------------------------------

diff --git a/scripts/gdb/linux/Makefile b/scripts/gdb/linux/Makefile
index 8b00031f53497035b68bfe65bd682989430fe016..ab3cfe727a4eeacaadceb1d16c0234dd774bf4be 100644 (file)
--- a/scripts/gdb/linux/Makefile
+++ b/scripts/gdb/linux/Makefile
@@ -1,6 +1,6 @@
 always := gdb-scripts
 
-SRCTREE := $(shell cd $(srctree) && /bin/pwd)
+SRCTREE := $(abspath $(srctree))
 
 $(obj)/gdb-scripts:
 ifneq ($(KBUILD_SRC),)

diff --git a/tools/power/cpupower/Makefile b/tools/power/cpupower/Makefile
index d6e1c02ddcfead4532cdc73f2d81207f62a8db5f..4c5a481a850c6d4490db28ae0d6448197e4b4517 100644 (file)
--- a/tools/power/cpupower/Makefile
+++ b/tools/power/cpupower/Makefile
@@ -26,7 +26,7 @@ endif
 
 ifneq ($(OUTPUT),)
 # check that the output directory actually exists
-OUTDIR := $(shell cd $(OUTPUT) && /bin/pwd)
+OUTDIR := $(realpath $(OUTPUT))
 $(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
 endif
 

diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
index ccad8ce925e427b845972adcf75694edf0e92b63..57a850978cef2fe5e5040659c00a57d88c760682 100644 (file)
--- a/tools/scripts/Makefile.include
+++ b/tools/scripts/Makefile.include
@@ -1,7 +1,7 @@
 ifneq ($(O),)
 ifeq ($(origin O), command line)
-       dummy := $(if $(shell test -d $(O) || echo $(O)),$(error O=$(O) does not exist),)
-       ABSOLUTE_O := $(shell cd $(O) ; pwd)
+       ABSOLUTE_O := $(realpath $(O))
+       dummy := $(if $(ABSOLUTE_O),,$(error O=$(O) does not exist))
        OUTPUT := $(ABSOLUTE_O)/$(if $(subdir),$(subdir)/)
        COMMAND_O := O=$(ABSOLUTE_O)
 ifeq ($(objtree),)
@@ -12,7 +12,7 @@ endif
 
 # check that the output directory actually exists
 ifneq ($(OUTPUT),)
-OUTDIR := $(shell cd $(OUTPUT) && /bin/pwd)
+OUTDIR := $(realpath $(OUTPUT))
 $(if $(OUTDIR),, $(error output directory "$(OUTPUT)" does not exist))
 endif