kbuild: remove ar-option and KBUILD_ARFLAGS

Commit 40df759e2b ("kbuild: Fix build with binutils <= 2.19")
introduced ar-option and KBUILD_ARFLAGS to deal with old binutils.

According to Documentation/process/changes.rst, the current minimal
supported version of binutils is 2.21 so you can assume the 'D' option
is always supported. Not only GNU ar but also llvm-ar supports it.

With the 'D' option hard-coded, there is no more user of ar-option
or KBUILD_ARFLAGS.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>

Documentation/kbuild/makefiles.rst

@@ -954,11 +954,6 @@ When kbuild executes, the following steps are followed (roughly):
 
 	From commandline LDFLAGS_MODULE shall be used (see kbuild.txt).
 
-    KBUILD_ARFLAGS   Options for $(AR) when creating archives
-
-	$(KBUILD_ARFLAGS) set by the top level Makefile to "D" (deterministic
-	mode) if this option is supported by $(AR).
-
     KBUILD_LDS
 
 	The linker script with full path. Assigned by the top-level Makefile.

Makefile

@@ -498,7 +498,6 @@ export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE CFLAGS_UBSAN
 export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
 export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
 export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
-export KBUILD_ARFLAGS
 
 # Files to ignore in find ... statements
 
@@ -914,9 +913,6 @@ ifdef CONFIG_RETPOLINE
 KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
 endif
 
-# use the deterministic mode of AR if available
-KBUILD_ARFLAGS := $(call ar-option,D)
-
 include scripts/Makefile.kasan
 include scripts/Makefile.extrawarn
 include scripts/Makefile.ubsan

arch/powerpc/boot/Makefile

@@ -50,7 +50,7 @@ endif
 
 BOOTAFLAGS	:= -D__ASSEMBLY__ $(BOOTCFLAGS) -nostdinc
 
-BOOTARFLAGS	:= -cr$(KBUILD_ARFLAGS)
+BOOTARFLAGS	:= -crD
 
 ifdef CONFIG_CC_IS_CLANG
 BOOTCFLAGS += $(CLANG_FLAGS)

scripts/Kbuild.include

@@ -143,11 +143,6 @@ cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || e
 # Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
 ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
 
-# ar-option
-# Usage: KBUILD_ARFLAGS := $(call ar-option,D)
-# Important: no spaces around options
-ar-option = $(call try-run, $(AR) rc$(1) "$$TMP",$(1),$(2))
-
 # ld-version
 # Note this is mainly for HJ Lu's 3 number binutil versions
 ld-version = $(shell $(LD) --version | $(srctree)/scripts/ld-version.sh)

scripts/Makefile.build

@@ -389,7 +389,7 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ;
 ifdef builtin-target
 
 quiet_cmd_ar_builtin = AR      $@
-      cmd_ar_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
+      cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs)
 
 $(builtin-target): $(real-obj-y) FORCE
 	$(call if_changed,ar_builtin)

scripts/Makefile.lib

@@ -232,7 +232,7 @@ quiet_cmd_ld = LD      $@
 # ---------------------------------------------------------------------------
 
 quiet_cmd_ar = AR      $@
-      cmd_ar = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
+      cmd_ar = rm -f $@; $(AR) cDPrsT $@ $(real-prereqs)
 
 # Objcopy
 # ---------------------------------------------------------------------------