kbuild: move samples/ to KBUILD_VMLINUX_OBJS

Handle samples/ like the other top-level directories to simplify
the Makefile.

Include include/config/auto.conf earlier to evaluate
drivers-$(CONFIG_SAMPLES).
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Makefile

@@ -598,20 +598,21 @@ endif
 
 export KBUILD_MODULES KBUILD_BUILTIN
 
+ifeq ($(dot-config),1)
+include include/config/auto.conf
+endif
+
 ifeq ($(KBUILD_EXTMOD),)
 # Objects we will link into vmlinux / subdirs we need to visit
 init-y		:= init/
 drivers-y	:= drivers/ sound/
+drivers-$(CONFIG_SAMPLES) += samples/
 net-y		:= net/
 libs-y		:= lib/
 core-y		:= usr/
 virt-y		:= virt/
 endif # KBUILD_EXTMOD
 
-ifeq ($(dot-config),1)
-include include/config/auto.conf
-endif
-
 # The all: target is the default when no target is given on the
 # command line.
 # This allow a user to issue only 'make' to build a kernel including modules
@@ -1006,7 +1007,7 @@ export KBUILD_VMLINUX_LIBS := $(libs-y1)
 export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds
 export LDFLAGS_vmlinux
 # used by scripts/package/Makefile
-export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Documentation include samples scripts tools)
+export KBUILD_ALLDIRS := $(sort $(filter-out arch/%,$(vmlinux-alldirs)) arch Documentation include scripts tools)
 
 vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS)
 
@@ -1043,11 +1044,8 @@ vmlinux: scripts/link-vmlinux.sh autoksyms_recursive $(vmlinux-deps) FORCE
 
 targets := vmlinux
 
-# Build samples along the rest of the kernel. This needs headers_install.
-ifdef CONFIG_SAMPLES
-vmlinux-dirs += samples
+# Some samples need headers_install.
 samples: headers_install
-endif
 
 # The actual objects are generated when descending,
 # make sure no implicit rule kicks in
@@ -1363,7 +1361,7 @@ MRPROPER_FILES += .config .config.old .version \
 #
 clean: rm-dirs  := $(CLEAN_DIRS)
 clean: rm-files := $(CLEAN_FILES)
-clean-dirs      := $(addprefix _clean_, . $(vmlinux-alldirs) Documentation samples)
+clean-dirs      := $(addprefix _clean_, . $(vmlinux-alldirs) Documentation)
 
 PHONY += $(clean-dirs) clean archclean vmlinuxclean
 $(clean-dirs):

samples/Makefile

 # Makefile for Linux samples code
 
-obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ livepatch/ \
+obj-y			+= kobject/ kprobes/ trace_events/ livepatch/ \
 			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
 			   configfs/ connector/ v4l/ trace_printk/ \
 			   vfio-mdev/ statx/ qmi/ binderfs/