Merge tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - do not generate unneeded top-level built-in.a

 - let git ignore O= directory entirely

 - optimize scripts/kallsyms slightly

 - exclude DWARF info from *.s regardless of config options

 - fix GCC toolchain search path for Clang to prepare ld.lld support

 - do not generate modules.order when CONFIG_MODULES is disabled

 - simplify single target rules and remove VPATH for external module
   build

 - allow to add optional flags to dpkg-buildpackage when building
   deb-pkg

 - move some compiler option tests from Makefile to Kconfig

 - various Makefile cleanups

* tag 'kbuild-v5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits)
  kbuild: remove scripts/basic/% build target
  kbuild: use -Werror=implicit-... instead of -Werror-implicit-...
  kbuild: clean up scripts/gcc-version.sh
  kbuild: remove cc-version macro
  kbuild: update comment block of scripts/clang-version.sh
  kbuild: remove commented-out INITRD_COMPRESS
  kbuild: move -gsplit-dwarf, -gdwarf-4 option tests to Kconfig
  kbuild: [bin]deb-pkg: add DPKG_FLAGS variable
  kbuild: move ".config not found!" message from Kconfig to Makefile
  kbuild: invoke syncconfig if include/config/auto.conf.cmd is missing
  kbuild: simplify single target rules
  kbuild: remove empty rules for makefiles
  kbuild: make -r/-R effective in top Makefile for old Make versions
  kbuild: move tools_silent to a more relevant place
  kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig
  kbuild: refactor cc-cross-prefix implementation
  kbuild: hardcode genksyms path and remove GENKSYMS variable
  scripts/gdb: refactor rules for symlink creation
  kbuild: create symlink to vmlinux-gdb.py in scripts_gdb target
  scripts/gdb: do not descend into scripts/gdb from scripts
  ...

6 files changed, 19 insertions, 23 deletions

diff --git a/arch/mips/boot/Makefile b/arch/mips/boot/Makefile
index 35704c28a28b..3ce4dd578370 100644
--- a/arch/mips/boot/Makefile
+++ b/arch/mips/boot/Makefile
@@ -115,7 +115,7 @@ endif
 targets += vmlinux.its.S
 
 quiet_cmd_its_cat = CAT     $@
-      cmd_its_cat = cat $(filter-out $(PHONY), $^) >$@
+      cmd_its_cat = cat $(real-prereqs) >$@
 
 $(obj)/vmlinux.its.S: $(addprefix $(srctree)/arch/mips/$(PLATFORM)/,$(ITS_INPUTS)) FORCE
 	$(call if_changed,its_cat)
diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index 0e8dadd011bc..73d1f3562978 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -218,7 +218,7 @@ quiet_cmd_bootas = BOOTAS  $@
       cmd_bootas = $(BOOTCC) -Wp,-MD,$(depfile) $(BOOTAFLAGS) -c -o $@ $<
 
 quiet_cmd_bootar = BOOTAR  $@
-      cmd_bootar = $(BOOTAR) $(BOOTARFLAGS) $@.$$$$ $(filter-out FORCE,$^); mv $@.$$$$ $@
+      cmd_bootar = $(BOOTAR) $(BOOTARFLAGS) $@.$$$$ $(real-prereqs); mv $@.$$$$ $@
 
 $(obj-libfdt): $(obj)/%.o: $(srctree)/scripts/dtc/libfdt/%.c FORCE
 	$(call if_changed_dep,bootcc)
diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile
index d5ad724f5c96..11ca8795b74a 100644
--- a/arch/s390/boot/Makefile
+++ b/arch/s390/boot/Makefile
@@ -58,7 +58,7 @@ $(obj)/compressed/vmlinux: $(obj)/startup.a FORCE
 	$(Q)$(MAKE) $(build)=$(obj)/compressed $@
 
 quiet_cmd_ar = AR      $@
-      cmd_ar = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(filter $(OBJECTS), $^)
+      cmd_ar = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
 
 $(obj)/startup.a: $(OBJECTS) FORCE
 	$(call if_changed,ar)
@@ -67,6 +67,6 @@ install: $(CONFIGURE) $(obj)/bzImage
 	sh -x  $(srctree)/$(obj)/install.sh $(KERNELRELEASE) $(obj)/bzImage \
 	      System.map "$(INSTALL_PATH)"
 
-chkbss := $(OBJECTS)
-chkbss-target := $(obj)/startup.a
+chkbss := $(obj-y)
+chkbss-target := startup.a
 include $(srctree)/arch/s390/scripts/Makefile.chkbss
diff --git a/arch/s390/boot/compressed/Makefile b/arch/s390/boot/compressed/Makefile
index b1bdd15e3429..fa529c5b4486 100644
--- a/arch/s390/boot/compressed/Makefile
+++ b/arch/s390/boot/compressed/Makefile
@@ -63,6 +63,6 @@ OBJCOPYFLAGS_piggy.o := -I binary -O elf64-s390 -B s390:64-bit --rename-section
 $(obj)/piggy.o: $(obj)/vmlinux.bin$(suffix-y) FORCE
 	$(call if_changed,objcopy)
 
-chkbss := $(filter-out $(obj)/piggy.o $(obj)/info.o,$(OBJECTS))
-chkbss-target := $(obj)/vmlinux.bin
+chkbss := $(filter-out piggy.o info.o, $(obj-y))
+chkbss-target := vmlinux.bin
 include $(srctree)/arch/s390/scripts/Makefile.chkbss
diff --git a/arch/s390/scripts/Makefile.chkbss b/arch/s390/scripts/Makefile.chkbss
index 9bba2c14e0ca..cd7e8f4419f5 100644
--- a/arch/s390/scripts/Makefile.chkbss
+++ b/arch/s390/scripts/Makefile.chkbss
@@ -1,23 +1,20 @@
 # SPDX-License-Identifier: GPL-2.0
 
+chkbss-target ?= built-in.a
+$(obj)/$(chkbss-target): chkbss
+
+chkbss-files := $(addsuffix .chkbss, $(chkbss))
+clean-files += $(chkbss-files)
+
+PHONY += chkbss
+chkbss: $(addprefix $(obj)/, $(chkbss-files))
+
 quiet_cmd_chkbss = CHKBSS  $<
-define cmd_chkbss
-	rm -f $@; \
+      cmd_chkbss = \
 	if ! $(OBJDUMP) -j .bss -w -h $< | awk 'END { if ($$3) exit 1 }'; then \
 		echo "error: $< .bss section is not empty" >&2; exit 1; \
 	fi; \
 	touch $@;
-endef
-
-chkbss-target ?= $(obj)/built-in.a
-ifneq (,$(findstring /,$(chkbss)))
-chkbss-files := $(patsubst %, %.chkbss, $(chkbss))
-else
-chkbss-files := $(patsubst %, $(obj)/%.chkbss, $(chkbss))
-endif
-
-$(chkbss-target): $(chkbss-files)
-targets += $(notdir $(chkbss-files))
 
-%.o.chkbss: %.o
+$(obj)/%.o.chkbss: $(obj)/%.o
 	$(call cmd,chkbss)
diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 96cb20de08af..f60501a384f9 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -37,8 +37,7 @@ REALMODE_OBJS = $(addprefix $(obj)/,$(realmode-y))
 sed-pasyms := -n -r -e 's/^([0-9a-fA-F]+) [ABCDGRSTVW] (.+)$$/pa_\2 = \2;/p'
 
 quiet_cmd_pasyms = PASYMS  $@
-      cmd_pasyms = $(NM) $(filter-out FORCE,$^) | \
-		   sed $(sed-pasyms) | sort | uniq > $@
+      cmd_pasyms = $(NM) $(real-prereqs) | sed $(sed-pasyms) | sort | uniq > $@
 
 targets += pasyms.h
 $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE