tools build: Add new build support

Adding new build framework into 'tools/build' to be used by tools.

There's no change for actual building at this point, it comes in the
next patches.

The idea and more details are explained in the
'tools/build/Documentation/Build.txt' file.

I adopted everything from the kernel build system, with some changes to
allow for multiple binaries build definitions.

While the kernel's build output is single image (forget modules) we need
to be able to build several binaries/libraries.

The basic idea is that sser provides 'Build' files with objects
definitions like:

  perf-y += a.o
  perf-y += b.o
  libperf-y += c.o
  libperf-y += d.o

and the build framework outputs files:

  perf-in.o    # a.o, b.o compiled in
  libperf-in.o # c.o, d.o compiled in

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-fbj22h4av0otlxupwcmrxgpa@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 97 insertions, 0 deletions

diff --git a/tools/build/Makefile.build b/tools/build/Makefile.build
new file mode 100644
index 000000000000..ae203f21cc86
--- /dev/null
+++ b/tools/build/Makefile.build
@@ -0,0 +1,97 @@
+###
+# Main build makefile.
+#
+#  Lots of this code have been borrowed or heavily inspired from parts
+#  of kbuild code, which is not credited, but mostly developed by:
+#
+#  Copyright (C) Sam Ravnborg <sam@mars.ravnborg.org>, 2015
+#  Copyright (C) Linus Torvalds <torvalds@linux-foundation.org>, 2015
+#
+
+PHONY := __build
+__build:
+
+ifeq ($(V),1)
+  quiet =
+else
+  quiet=quiet_
+endif
+
+build-dir := $(srctree)/tools/build
+
+# Generic definitions
+include $(build-dir)/Build.include
+
+# Init all relevant variables used in build files so
+# 1) they have correct type
+# 2) they do not inherit any value from the environment
+subdir-y     :=
+obj-y        :=
+subdir-y     :=
+subdir-obj-y :=
+
+# Build definitions
+build-file := $(dir)/Build
+include $(build-file)
+
+# Compile command
+quiet_cmd_cc_o_c = CC       $@
+      cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
+
+# Link agregate command
+# If there's nothing to link, create empty $@ object.
+quiet_cmd_ld_multi = LD       $@
+      cmd_ld_multi = $(if $(strip $(obj-y)),\
+		       $(LD) -r -o $@ $(obj-y),rm -f $@; $(AR) rcs $@)
+
+# Build rules
+$(OUTPUT)%.o: %.c FORCE
+	$(call if_changed_dep,cc_o_c)
+
+$(OUTPUT)%.o: %.S FORCE
+	$(call if_changed_dep,cc_o_c)
+
+# Gather build data:
+#   obj-y        - list of build objects
+#   subdir-y     - list of directories to nest
+#   subdir-obj-y - list of directories objects 'dir/$(obj)-in.o'
+obj-y        := $($(obj)-y)
+subdir-y     := $(patsubst %/,%,$(filter %/, $(obj-y)))
+obj-y        := $(patsubst %/, %/$(obj)-in.o, $(obj-y))
+subdir-obj-y := $(filter %/$(obj)-in.o, $(obj-y))
+
+# '$(OUTPUT)/dir' prefix to all objects
+prefix       := $(subst ./,,$(OUTPUT)$(dir)/)
+obj-y        := $(addprefix $(prefix),$(obj-y))
+subdir-obj-y := $(addprefix $(prefix),$(subdir-obj-y))
+
+# Final '$(obj)-in.o' object
+in-target := $(prefix)$(obj)-in.o
+
+PHONY += $(subdir-y)
+
+$(subdir-y):
+	@$(MAKE) -f $(build-dir)/Makefile.build dir=$(dir)/$@ obj=$(obj)
+
+$(sort $(subdir-obj-y)): $(subdir-y) ;
+
+$(in-target): $(obj-y) FORCE
+	$(call rule_mkdir)
+	$(call if_changed,ld_multi)
+
+__build: $(in-target)
+	@:
+
+PHONY += FORCE
+FORCE:
+
+# Include all cmd files to get all the dependency rules
+# for all objects included
+targets   := $(wildcard $(sort $(obj-y) $(in-target)))
+cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
+
+ifneq ($(cmd_files),)
+  include $(cmd_files)
+endif
+
+.PHONY: $(PHONY)