kbuild: Don't reset timestamps in include/generated if not needed
Use filechk to generate asm-offsets.h and bounds.h. Based on a patch by
Valdis Kletnieks.
Reported-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Acked-By: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
diff --git a/Kbuild b/Kbuild
index ab8ded9..96d0629 100644
--- a/Kbuild
+++ b/Kbuild
@@ -13,8 +13,9 @@
s:->::; p;}"
endef
-quiet_cmd_offsets = GEN $@
-define cmd_offsets
+# Use filechk to avoid rebuilds when a header changes, but the resulting file
+# does not
+define filechk_offsets
(set -e; \
echo "#ifndef $2"; \
echo "#define $2"; \
@@ -24,9 +25,9 @@
echo " * This file was generated by Kbuild"; \
echo " */"; \
echo ""; \
- sed -ne $(sed-y) $<; \
+ sed -ne $(sed-y); \
echo ""; \
- echo "#endif" ) > $@
+ echo "#endif" )
endef
#####
@@ -42,9 +43,8 @@
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
-$(obj)/$(bounds-file): kernel/bounds.s Kbuild
- $(Q)mkdir -p $(dir $@)
- $(call cmd,offsets,__LINUX_BOUNDS_H__)
+$(obj)/$(bounds-file): kernel/bounds.s FORCE
+ $(call filechk,offsets,__LINUX_BOUNDS_H__)
#####
# 2) Generate asm-offsets.h
@@ -62,8 +62,8 @@
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
-$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
- $(call cmd,offsets,__ASM_OFFSETS_H__)
+$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
+ $(call filechk,offsets,__ASM_OFFSETS_H__)
#####
# 3) Check for missing system calls