On Tue, Jul 10, 2018 at 10:35:16AM +0900, Masahiro Yamada wrote: > Currently, users are allowed to enable STACK_VALIDATION regardless > of the compiler capability. The top-level Makefile warns or breaks > the build if it turns out that the host compiler cannot link libelf. > > Move the libelf test to Kconfig so that users can enable the feature > only when the host compiler can build the objtool. The ugly check > in the Makefile will go away. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> > Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Actually, looking at this again, I want to rescind my ack. This patches changes the behavior in a subtle (but important) way. Before, if I did "make defconfig", it would *always* choose the ORC unwinder. Then, if I didn't have libelf-devel, the build would fail and it would tell me what I need to install. But now with this patch, if I do "make defconfig", the generated config actually changes based on what I happen to have installed on my build system. If I don't have libelf-devel, then it silently chooses the non-default unwinder (frame pointer). This is a subtle difference, but IMO it's dangerous, because it will silently enable the frame pointer unwinder for the majority of new systems, even though it's not the default. I strongly prefer the original behavior, because we really want to encourage people to use the ORC unwinder, even if that means they have to install a package to build it. Also -- in general -- I suspect that silently changing the defaults like this will create a lot of bad surprises. The output of "make defconfig" should be predictable and not dependent on what RPMs I happen to have installed. -- Josh -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
