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kbuild: remove extra ifdef/endif of top Makefile 

The GNU make's origin function know undefined variable well,
so the outer ifdef/endif conditional checking is unneeded.

From `info make` documentation, origin will return

  `undefined'
     if VARIABLE was never defined.
  `command line'
     if VARIABLE was defined on the command line.
   ...

Therefore, $(origin V) will get a value anyway, killing ifdef/endif is
viable and safe.

Furthermore, I've checked the minimal requirements from
Documentation/Changes is GNU make 3.79.1, and that version of GNU make
has support of origin function well already, so now it's safe to kill
the outer conditional checking, without upgrading the minimal
requirements.

Signed-off-by: Cheng Renquan <crq@kernel.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
This commit is contained in:
Cheng Renquan 2009-05-26 16:03:07 +08:00 committed by Sam Ravnborg
parent 3e56f08bff
commit b8b0618cf6
1 changed files with 9 additions and 17 deletions
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26
Makefile
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@ -35,10 +35,8 @@ MAKEFLAGS += -rR --no-print-directory
# To put more focus on warnings, be less verbose as default
# Use 'make V=1' to see the full commands
ifdef V
ifeq ("$(origin V)", "command line")
KBUILD_VERBOSE = $(V)
endif
ifeq ("$(origin V)", "command line")
KBUILD_VERBOSE = $(V)
endif
ifndef KBUILD_VERBOSE
KBUILD_VERBOSE = 0
@ -54,10 +52,8 @@ endif
# See the file "Documentation/sparse.txt" for more details, including
# where to get the "sparse" utility.
ifdef C
ifeq ("$(origin C)", "command line")
KBUILD_CHECKSRC = $(C)
endif
ifeq ("$(origin C)", "command line")
KBUILD_CHECKSRC = $(C)
endif
ifndef KBUILD_CHECKSRC
KBUILD_CHECKSRC = 0
@ -69,12 +65,10 @@ endif
ifdef SUBDIRS
KBUILD_EXTMOD ?= $(SUBDIRS)
endif
ifdef M
ifeq ("$(origin M)", "command line")
KBUILD_EXTMOD := $(M)
endif
endif
ifeq ("$(origin M)", "command line")
KBUILD_EXTMOD := $(M)
endif
# kbuild supports saving output files in a separate directory.
# To locate output files in a separate directory two syntaxes are supported.
@ -98,10 +92,8 @@ ifeq ($(KBUILD_SRC),)
# OK, Make called in directory where kernel src resides
# Do we want to locate output files in a separate directory?
ifdef O
ifeq ("$(origin O)", "command line")
KBUILD_OUTPUT := $(O)
endif
ifeq ("$(origin O)", "command line")
KBUILD_OUTPUT := $(O)
endif
# That's our default target when none is given on the command line