tools build: Add subdir support

Add support to make directory any time we build objects out of the tree
(O=/tmp/krava) and the output directory does not exist.

Signed-off-by: Jiri Olsa <[email protected]>
Tested-by: Sukadev Bhattiprolu <[email protected]>
Tested-by: Will Deacon <[email protected]>
Cc: Alexis Berlemont <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Corey Ashford <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/build/Makefile.build

@@ -37,6 +37,11 @@ subdir-obj-y :=
 build-file := $(dir)/Build
 include $(build-file)
 
+# Create directory unless it exists
+quiet_cmd_mkdir = MKDIR    $(dir $@)
+      cmd_mkdir = mkdir -p $(dir $@)
+     rule_mkdir = $(if $(wildcard $(dir $@)),,@$(call echo-cmd,mkdir) $(cmd_mkdir))
+
 # Compile command
 quiet_cmd_cc_o_c = CC       $@
       cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
@@ -49,9 +54,11 @@ quiet_cmd_ld_multi = LD       $@
 
 # Build rules
 $(OUTPUT)%.o: %.c FORCE
+	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)
 
 $(OUTPUT)%.o: %.S FORCE
+	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)
 
 # Gather build data: