[U-Boot] [PATCH 1/2] kbuild: add .DELETE_ON_ERROR special target

[Masahiro Yamada]

Linux commit 9c2af1c7377a8a6ef86e5cabf80978f3dbbb25c0

If Make gets a fatal signal while a shell is executing, it may delete
the target file that the recipe was supposed to update.  This is needed
to make sure that it is remade from scratch when Make is next run; if
Make is interrupted after the recipe has begun to write the target file,
it results in an incomplete file whose time stamp is newer than that
of the prerequisites files.  Make automatically deletes the incomplete
file on interrupt unless the target is marked .PRECIOUS.

The situation is just the same as when the shell fails for some reasons.
Usually when a recipe line fails, if it has changed the target file at
all, the file is corrupted, or at least it is not completely updated.
Yet the file’s time stamp says that it is now up to date, so the next
time Make runs, it will not try to update that file.

However, Make does not cater to delete the incomplete target file in
this case.  We need to add .DELETE_ON_ERROR somewhere in the Makefile
to request it.

scripts/Kbuild.include seems a suitable place to add it because it is
included from almost all sub-makes.

Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
---

 scripts/Kbuild.include | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 13ebddd..460acd6 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -315,6 +315,9 @@ why =                                                                        \
 echo-why = $(call escsq, $(strip $(why)))
 endif
 
+# delete partially updated (i.e. corrupted) files on error
+.DELETE_ON_ERROR:
+
 ifdef CONFIG_SPL_BUILD
 SPL_ := SPL_
 ifeq ($(CONFIG_TPL_BUILD),y)
-- 
2.7.4