[XEN PATCH v8 15/47] build: hook kconfig into xen build system

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

Now that xen's build system is very close to Linux's ones, we can hook
"Makefile.host" into Xen's build system, and we can build Kconfig with
that.

"tools/kconfig/Makefile" now needs a workaround to not rebuild
"$(XEN_ROOT)/.config", as `make` tries the rules "%.config" which
fails with:
    tools/kconfig/Makefile:95: *** No configuration exists for this target on 
this architecture.  Stop.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---

Notes:
    v8:
    - reviewed
    - adjust Makefile.host to use the renamed macro "multi-depend".
    - move .config empty rules workaround into kconfig/Makefile (from Rules.mk)
      and merge the change of patch
            build: add an other explicite rules to not build $(XEN_ROOT)/.config
      into
            build: hook kconfig into xen build system

 xen/Makefile                                 |  34 ++++--
 xen/Rules.mk                                 |  13 ++-
 xen/scripts/Kbuild.include                   |  31 ++++++
 xen/scripts/Makefile.clean                   |  11 +-
 xen/{tools/kconfig => scripts}/Makefile.host |  11 +-
 xen/tools/kconfig/Makefile                   |   3 +
 xen/tools/kconfig/Makefile.kconfig           | 106 -------------------
 7 files changed, 86 insertions(+), 123 deletions(-)
 rename xen/{tools/kconfig => scripts}/Makefile.host (95%)
 delete mode 100644 xen/tools/kconfig/Makefile.kconfig

diff --git a/xen/Makefile b/xen/Makefile
index d38425234c6c..c26c44818916 100644
--- a/xen/Makefile
+++ b/xen/Makefile
@@ -40,6 +40,7 @@ ARCH=$(XEN_TARGET_ARCH)
 SRCARCH=$(shell echo $(ARCH) | \
           sed -e 's/x86.*/x86/' -e s'/arm\(32\|64\)/arm/g' \
               -e s'/riscv.*/riscv/g')
+export ARCH SRCARCH
 
 # Don't break if the build process wasn't called from the top level
 # we need XEN_TARGET_ARCH to generate the proper config
@@ -163,6 +164,13 @@ ifneq ($(filter %config,$(MAKECMDGOALS)),)
     config-build := y
 endif
 
+export CONFIG_SHELL := $(SHELL)
+export YACC = $(if $(BISON),$(BISON),bison)
+export LEX = $(if $(FLEX),$(FLEX),flex)
+
+# Default file for 'make defconfig'.
+export KBUILD_DEFCONFIG := $(ARCH)_defconfig
+
 # CLANG_FLAGS needs to be calculated before calling Kconfig
 ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
 CLANG_FLAGS :=
@@ -203,9 +211,6 @@ PHONY += tools_fixdep
 tools_fixdep:
        $(MAKE) -C tools fixdep
 
-# Shorthand for kconfig
-kconfig = -f $(BASEDIR)/tools/kconfig/Makefile.kconfig ARCH=$(ARCH) 
SRCARCH=$(SRCARCH) HOSTCC="$(HOSTCC)" HOSTCXX="$(HOSTCXX)"
-
 ifeq ($(config-build),y)
 # ===========================================================================
 # *config targets only - make sure prerequisites are updated, and descend
@@ -221,14 +226,14 @@ filechk_kconfig_allconfig = \
 .allconfig.tmp: FORCE
        set -e; { $(call filechk_kconfig_allconfig); } > $@
 
-config: FORCE
-       $(MAKE) $(kconfig) $@
+config: tools_fixdep FORCE
+       $(Q)$(MAKE) $(build)=tools/kconfig $@
 
 # Config.mk tries to include .config file, don't try to remake it
 %/.config: ;
 
-%config: .allconfig.tmp FORCE
-       $(MAKE) $(kconfig) KCONFIG_ALLCONFIG=$< $@
+%config: .allconfig.tmp tools_fixdep FORCE
+       $(Q)$(MAKE) $(build)=tools/kconfig KCONFIG_ALLCONFIG=$< $@
 
 else # !config-build
 
@@ -238,9 +243,15 @@ ifeq ($(need-config),y)
 # changes are detected.
 -include include/config/auto.conf.cmd
 
+# This allows make to build fixdep before invoking defconfig. We can't use
+# "tools_fixdep" which is a .PHONY target and would force make to call
+# "defconfig" again to update $(KCONFIG_CONFIG).
+tools/fixdep:
+       $(MAKE) -C tools fixdep
+
 # Allow people to just run `make` as before and not force them to configure
-$(KCONFIG_CONFIG):
-       $(MAKE) $(kconfig) defconfig
+$(KCONFIG_CONFIG): tools/fixdep
+       $(Q)$(MAKE) $(build)=tools/kconfig defconfig
 
 # The actual configuration files used during the build are stored in
 # include/generated/ and include/config/. Update them if .config is newer than
@@ -249,7 +260,7 @@ $(KCONFIG_CONFIG):
 # This exploits the 'multi-target pattern rule' trick.
 # The syncconfig should be executed only once to make all the targets.
 include/config/%.conf include/config/%.conf.cmd: $(KCONFIG_CONFIG)
-       $(MAKE) $(kconfig) syncconfig
+       $(Q)$(MAKE) $(build)=tools/kconfig syncconfig
 
 ifeq ($(CONFIG_DEBUG),y)
 CFLAGS += -O1
@@ -409,9 +420,10 @@ _clean:
        $(MAKE) $(clean) arch/riscv
        $(MAKE) $(clean) arch/x86
        $(MAKE) $(clean) test
-       $(MAKE) $(kconfig) clean
+       $(MAKE) $(clean) tools/kconfig
        find . \( -name "*.o" -o -name ".*.d" -o -name ".*.d2" \
                -o -name ".*.o.tmp" -o -name "*~" -o -name "core" \
+               -o -name '*.lex.c' -o -name '*.tab.[ch]' \
                -o -name "*.gcno" -o -name ".*.cmd" -o -name "lib.a" \) -exec 
rm -f {} \;
        rm -f include/asm $(TARGET) $(TARGET).gz $(TARGET).efi 
$(TARGET).efi.map $(TARGET)-syms $(TARGET)-syms.map *~ core
        rm -f asm-offsets.s arch/*/include/asm/asm-offsets.h
diff --git a/xen/Rules.mk b/xen/Rules.mk
index d32fec0ae037..f452a821cc86 100644
--- a/xen/Rules.mk
+++ b/xen/Rules.mk
@@ -89,6 +89,13 @@ subdir-y        := $(addprefix $(obj)/,$(subdir-y))
 nocov-y         := $(addprefix $(obj)/,$(nocov-y))
 noubsan-y       := $(addprefix $(obj)/,$(noubsan-y))
 
+# Do not include hostprogs rules unless needed.
+# $(sort ...) is used here to remove duplicated words and excessive spaces.
+hostprogs-y := $(sort $(hostprogs-y))
+ifneq ($(hostprogs-y),)
+include scripts/Makefile.host
+endif
+
 # subdir-builtin may contain duplications. Use $(sort ...)
 subdir-builtin := $(sort $(filter %/built_in.o, $(obj-y)))
 
@@ -267,7 +274,11 @@ intermediate_targets = $(foreach sfx, $(2), \
                                $(patsubst %$(strip $(1)),%$(sfx), \
                                        $(filter %$(strip $(1)), $(targets))))
 # %.init.o <- %.o
-targets += $(call intermediate_targets, .init.o, .o)
+# %.lex.o <- %.lex.c <- %.l
+# %.tab.o <- %.tab.[ch] <- %.y
+targets += $(call intermediate_targets, .init.o, .o) \
+          $(call intermediate_targets, .lex.o, .lex.c) \
+          $(call intermediate_targets, .tab.o, .tab.c .tab.h)
 
 # Build
 # ---------------------------------------------------------------------------
diff --git a/xen/scripts/Kbuild.include b/xen/scripts/Kbuild.include
index 6be38301e835..79b42e1252d6 100644
--- a/xen/scripts/Kbuild.include
+++ b/xen/scripts/Kbuild.include
@@ -25,6 +25,37 @@ real-prereqs = $(filter-out $(PHONY), $^)
 # Escape single quote for use in echo statements
 escsq = $(subst $(squote),'\$(squote)',$1)
 
+###
+# Easy method for doing a status message
+       kecho := :
+ quiet_kecho := echo
+silent_kecho := :
+kecho := $($(quiet)kecho)
+
+###
+# filechk is used to check if the content of a generated file is updated.
+# Sample usage:
+#
+# filechk_sample = echo $(KERNELRELEASE)
+# version.h: FORCE
+#      $(call filechk,sample)
+#
+# The rule defined shall write to stdout the content of the new file.
+# The existing file will be compared with the new one.
+# - If no file exist it is created
+# - If the content differ the new file is used
+# - If they are equal no change, and no timestamp update
+define filechk
+       $(Q)set -e;                                             \
+       mkdir -p $(dir $@);                                     \
+       trap "rm -f $(dot-target).tmp" EXIT;                    \
+       { $(filechk_$(1)); } > $(dot-target).tmp;               \
+       if [ ! -r $@ ] || ! cmp -s $@ $(dot-target).tmp; then   \
+               $(kecho) '  UPD     $@';                        \
+               mv -f $(dot-target).tmp $@;                     \
+       fi
+endef
+
 # as-insn: Check whether assembler supports an instruction.
 # Usage: cflags-y += $(call as-insn,CC FLAGS,"insn",option-yes,option-no)
 as-insn = $(if $(shell echo 'void _(void) { asm volatile ( $(2) ); }' \
diff --git a/xen/scripts/Makefile.clean b/xen/scripts/Makefile.clean
index c3b0681611da..156d6307cf83 100644
--- a/xen/scripts/Makefile.clean
+++ b/xen/scripts/Makefile.clean
@@ -17,8 +17,17 @@ include $(src)/Makefile
 subdir-all := $(subdir-y) $(subdir-n) $(subdir-) \
               $(patsubst %/,%, $(filter %/, $(obj-y) $(obj-n) $(obj-)))
 
+__clean-files := \
+    $(clean-files) $(hostprogs-y) $(hostprogs-)
+
+__clean-files := $(wildcard $(__clean-files))
+
 .PHONY: clean
-clean:: $(subdir-all) ;
+clean:: $(subdir-all)
+ifneq ($(strip $(__clean-files)),)
+       rm -rf $(__clean-files)
+endif
+       @:
 
 # Descending
 # ---------------------------------------------------------------------------
diff --git a/xen/tools/kconfig/Makefile.host b/xen/scripts/Makefile.host
similarity index 95%
rename from xen/tools/kconfig/Makefile.host
rename to xen/scripts/Makefile.host
index 4c51c95d40f4..8a85f94316bc 100644
--- a/xen/tools/kconfig/Makefile.host
+++ b/xen/scripts/Makefile.host
@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 
+# target with $(obj)/ and its suffix stripped
+target-stem = $(basename $(patsubst $(obj)/%,%,$@))
+
 # LEX
 # ---------------------------------------------------------------------------
 quiet_cmd_flex = LEX     $@
@@ -114,7 +117,7 @@ quiet_cmd_host-cmulti       = HOSTLD  $@
                          $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem))
 $(host-cmulti): FORCE
        $(call if_changed,host-cmulti)
-$(call multi_depend, $(host-cmulti), , -objs)
+$(call multi-depend, $(host-cmulti), , -objs)
 
 # Create .o file from a single .c file
 # host-cobjs -> .o
@@ -132,7 +135,7 @@ quiet_cmd_host-cxxmulti     = HOSTLD  $@
                          $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem))
 $(host-cxxmulti): FORCE
        $(call if_changed,host-cxxmulti)
-$(call multi_depend, $(host-cxxmulti), , -objs -cxxobjs)
+$(call multi-depend, $(host-cxxmulti), , -objs -cxxobjs)
 
 # Create .o file from a single .cc (C++) file
 quiet_cmd_host-cxxobjs = HOSTCXX $@
@@ -165,7 +168,7 @@ quiet_cmd_host-cshlib       = HOSTLLD -shared $@
                          $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem).so)
 $(host-cshlib): FORCE
        $(call if_changed,host-cshlib)
-$(call multi_depend, $(host-cshlib), .so, -objs)
+$(call multi-depend, $(host-cshlib), .so, -objs)
 
 # Link a shared library, based on position independent .o files
 # *.o -> .so shared library (host-cxxshlib)
@@ -175,7 +178,7 @@ quiet_cmd_host-cxxshlib     = HOSTLLD -shared $@
                          $(KBUILD_HOSTLDLIBS) $(HOSTLDLIBS_$(target-stem).so)
 $(host-cxxshlib): FORCE
        $(call if_changed,host-cxxshlib)
-$(call multi_depend, $(host-cxxshlib), .so, -objs)
+$(call multi-depend, $(host-cxxshlib), .so, -objs)
 
 targets += $(host-csingle)  $(host-cmulti) $(host-cobjs)\
           $(host-cxxmulti) $(host-cxxobjs) $(host-cshlib) $(host-cshobjs) 
$(host-cxxshlib) $(host-cxxshobjs)
diff --git a/xen/tools/kconfig/Makefile b/xen/tools/kconfig/Makefile
index f39521a0ed5b..b7b9a419ad59 100644
--- a/xen/tools/kconfig/Makefile
+++ b/xen/tools/kconfig/Makefile
@@ -91,6 +91,9 @@ endif
 
 configfiles=$(wildcard $(srctree)/kernel/configs/$@ 
$(srctree)/arch/$(SRCARCH)/configs/$@)
 
+# Don't try to remake this file included by Config.mk.
+$(XEN_ROOT)/.config: ;
+
 %.config: $(obj)/conf
        $(if $(call configfiles),, $(error No configuration exists for this 
target on this architecture))
        $(Q)$(CONFIG_SHELL) $(srctree)/tools/kconfig/merge_config.sh -m .config 
$(configfiles)
diff --git a/xen/tools/kconfig/Makefile.kconfig 
b/xen/tools/kconfig/Makefile.kconfig
deleted file mode 100644
index 799321ec4d07..000000000000
--- a/xen/tools/kconfig/Makefile.kconfig
+++ /dev/null
@@ -1,106 +0,0 @@
-# xen/tools/kconfig
-
-# default rule to do nothing
-all:
-
-# Xen doesn't have a silent build flag
-quiet :=
-Q :=
-kecho := :
-
-# eventually you'll want to do out of tree builds
-srctree := $(BASEDIR)
-objtree := $(srctree)
-src := tools/kconfig
-obj := $(src)
-
-# handle functions (most of these lifted from different Linux makefiles
-dot-target = $(dir $@).$(notdir $@)
-depfile = $(subst $(comma),,$(dot-target).d)
-basetarget = $(basename $(notdir $@))
-# target with $(obj)/ and its suffix stripped
-target-stem = $(basename $(patsubst $(obj)/%,%,$@))
-cmd = $(cmd_$(1))
-if_changed = $(cmd_$(1))
-if_changed_dep = $(cmd_$(1))
-
-###
-# filechk is used to check if the content of a generated file is updated.
-# Sample usage:
-#
-# filechk_sample = echo $(KERNELRELEASE)
-# version.h: FORCE
-#      $(call filechk,sample)
-#
-# The rule defined shall write to stdout the content of the new file.
-# The existing file will be compared with the new one.
-# - If no file exist it is created
-# - If the content differ the new file is used
-# - If they are equal no change, and no timestamp update
-# - stdin is piped in from the first prerequisite ($<) so one has
-#   to specify a valid file as first prerequisite (often the kbuild file)
-define filechk
-       $(Q)set -e;                             \
-       mkdir -p $(dir $@);                     \
-       { $(filechk_$(1)); } > $@.tmp;          \
-       if [ -r $@ ] && cmp -s $@ $@.tmp; then  \
-               rm -f $@.tmp;                   \
-       else                                    \
-               $(kecho) '  UPD     $@';        \
-               mv -f $@.tmp $@;                \
-       fi
-endef
-
-define multi_depend
-$(foreach m, $(notdir $1), \
-       $(eval $(obj)/$m: \
-       $(addprefix $(obj)/, $(foreach s, $3, $($(m:%$(strip $2)=%$(s)))))))
-endef
-
-# Set our default defconfig file
-KBUILD_DEFCONFIG := $(ARCH)_defconfig
-
-# provide our shell
-CONFIG_SHELL := $(SHELL)
-
-# provide the host compiler
-HOSTCC ?= gcc
-HOSTCXX ?= g++
-YACC = $(if $(BISON),$(BISON),bison)
-LEX = $(if $(FLEX),$(FLEX),flex)
-
-# force target
-PHONY += FORCE
-
-FORCE:
-
-# include the original Makefile and Makefile.host from Linux
-include $(src)/Makefile
-include $(src)/Makefile.host
-
-# Add intermediate targets:
-# When building objects with specific suffix patterns, add intermediate
-# targets that the final targets are derived from.
-intermediate_targets = $(foreach sfx, $(2), \
-                               $(patsubst %$(strip $(1)),%$(sfx), \
-                                       $(filter %$(strip $(1)), $(targets))))
-
-# %.lex.o <- %.lex.c <- %.l
-# %.tab.o <- %.tab.[ch] <- %.y
-targets += $(call intermediate_targets, .lex.o, .lex.c) \
-          $(call intermediate_targets, .tab.o, .tab.c .tab.h)
-
-# clean up rule
-clean-deps = $(foreach f,$(host-cobjs) $(host-cxxobjs),$(dir $f).$(notdir 
$f).d)
-clean-shipped = $(patsubst %_shipped,%,$(wildcard $(obj)/*_shipped))
-
-clean:
-       rm -rf $(clean-files)
-       rm -rf $(clean-deps)
-       rm -rf $(host-csingle) $(host-cmulti) $(host-cxxmulti) $(host-cobjs) 
$(host-cxxobjs)
-       rm -rf $(clean-shipped)
-
-$(obj)/zconf%: $(src)/zconf%_shipped
-       cp -f $< $@
-
-.PHONY: $(PHONY)
-- 
Anthony PERARD