On Fri, Jul 06, 2018 at 03:37:58PM +0900, Masahiro Yamada wrote: > >> > > Also see https://bugzilla.kernel.org/show_bug.cgi?id=200385 , > >> > > > >> > > 0a1756bd2897951c03c1cb671bdfd40729ac2177 is acting up > >> > > too with the same symptoms > >> > > >> > I tracked it down to -flto in LDFLAGS. I'll look more into this. > >> > >> -flto in LDFLAGS screws up this part of paging_prepare(): > > > > +Masahiro, Michal. > > > > I've got it wrong. *Any* LDFLAGS option passed to make this way: > > > > make LDFLAGS="..." > > > > would cause a issue. Even empty. > > > > It overrides all assignments to the variable in the makefile. > > As result the image is built without -pie and linker doesn't generate > > position independed code. > > > > Looks like the patch below helps, but my make-fu is poor. > > I don't see many override directives in kernel makefiles. > > It makes me think that there's a better way to fix this. > > > > Hm? > > > LDFLAGS is for internal-use. > Please do not override it from the command line. Can we generate a build error if a user try to override LDFLAGS, CFLAGS or other critical internal-use-only variables? This breakage was rather hard to debug. We need to have some kind of fail-safe for the future. > You want to pass your own linker flags > for building vmlinux and modules, > but do not want to pass them to > the decompressor (arch/x86/boot/compressed). > > Correct? I personally don't think that changing compiler/linker options for kernel build is good idea in general. > Kbuild provides a way for users > to pass additional linker flags to modules. > (LDFLAGS_MODULE) > > > But, there is no way to do that for vmlinux. > > It is easy to support it, though. > > https://patchwork.kernel.org/patch/10510833/ > > If this is the one you want, I can merge this. > > > make LDFLAGS_KERNEL=... LDFLAGS_MODULE=... > will allow you to append linker flags. Okay. It makes me wounder if we should taint kernel in such cases? Custom compiler/linker flags are risky and can lead to weird bugs. -- Kirill A. Shutemov -- To unsubscribe from this list: send the line "unsubscribe linux-x86_64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
