From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751634AbeBZXXM (ORCPT ); Mon, 26 Feb 2018 18:23:12 -0500 Received: from mail-wr0-f196.google.com ([209.85.128.196]:33803 "EHLO mail-wr0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750969AbeBZXXK (ORCPT ); Mon, 26 Feb 2018 18:23:10 -0500 X-Google-Smtp-Source: AH8x2245Ty23az9xv0R1hA/G9LPoJSzHTv90THCEIJPJh5kcv/Eo7W3OgTpuQRjFckBuknhwLTFCoB4+kwAi7UyztKM= MIME-Version: 1.0 References: <1519361813-8553-1-git-send-email-yamada.masahiro@socionext.com> <1519361813-8553-2-git-send-email-yamada.masahiro@socionext.com> In-Reply-To: <1519361813-8553-2-git-send-email-yamada.masahiro@socionext.com> From: Nick Desaulniers Date: Mon, 26 Feb 2018 23:22:58 +0000 Message-ID: Subject: Re: [PATCH 2/2] kbuild: simplify ld-option implementation To: Masahiro Yamada Cc: Linux Kbuild mailing list , Arnd Bergmann , sam@ravnborg.org, Matthias Kaehlcke , Cao jin , Mark Charlebois , forney@google.com, LKML , Doug Anderson , Josh Poimboeuf , Ingo Molnar Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Nice! Now we don't need to invoke $CC to find out info about linker support. Signed-off-by: Nick Desaulniers Tested-by: Nick Desaulniers On Thu, Feb 22, 2018 at 8:57 PM Masahiro Yamada < yamada.masahiro@socionext.com> wrote: > Currently, linker options are tested by the coordination of $(CC) and > $(LD) because LD needs some object to link. > As commit 86a9df597cdd ("kbuild: fix linker feature test macros when > cross compiling with Clang") addressed, we need to make sure $(CC) > and $(LD) agree the underlying architecture of the passed object. > This could be a bit complex when we combine tools from different groups. > For example, we can use clang for $(CC), but we still need to rely on > GCC toolchain for $(LD). > So, I was searching a way for standalone testing of linker options. > A trick I found is to use '-v'. This prints the version string, but > also tests if the given option is recognized. > If a given option is supported, > $ aarch64-linux-gnu-ld -v --fix-cortex-a53-843419 > GNU ld (Linaro_Binutils-2017.11) 2.28.2.20170706 > $ echo $? > 0 > If unsupported, > $ aarch64-linux-gnu-ld -v --fix-cortex-a53-843419 > GNU ld (crosstool-NG linaro-1.13.1-4.7-2013.04-20130415 - Linaro GCC > 2013.04) 2.23.1 > aarch64-linux-gnu-ld: unrecognized option '--fix-cortex-a53-843419' > aarch64-linux-gnu-ld: use the --help option for usage information > $ echo $? > 1 > Gold works likewise. > $ aarch64-linux-gnu-ld.gold -v --fix-cortex-a53-843419 > GNU gold (Linaro_Binutils-2017.11 2.28.2.20170706) 1.14 > masahiro@pug:~/ref/linux$ echo $? > 0 > $ aarch64-linux-gnu-ld.gold -v --fix-cortex-a53-999999 > GNU gold (Linaro_Binutils-2017.11 2.28.2.20170706) 1.14 > aarch64-linux-gnu-ld.gold: --fix-cortex-a53-999999: unknown option > aarch64-linux-gnu-ld.gold: use the --help option for usage information > $ echo $? > 1 > LLD too. > $ ld.lld -v --gc-sections > LLD 7.0.0 (http://llvm.org/git/lld.git > 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers) > $ echo $? > 0 > $ ld.lld -v --fix-cortex-a53-843419 > LLD 7.0.0 (http://llvm.org/git/lld.git > 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers) > $ echo $? > 0 > $ ld.lld -v --fix-cortex-a53-999999 > ld.lld: error: unknown argument: --fix-cortex-a53-999999 > LLD 7.0.0 (http://llvm.org/git/lld.git > 4a0e4190e74cea19f8a8dc625ccaebdf8b5d1585) (compatible with GNU linkers) > $ echo $? > 1 > Signed-off-by: Masahiro Yamada > --- > scripts/Kbuild.include | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include > index 34cbd81..f9c2f07 100644 > --- a/scripts/Kbuild.include > +++ b/scripts/Kbuild.include > @@ -237,9 +237,7 @@ cc-ldoption = $(call try-run-cached,\ > # ld-option > # Usage: LDFLAGS += $(call ld-option, -X) > -ld-option = $(call try-run-cached,\ > - $(CC) $(KBUILD_CPPFLAGS) $(CC_OPTION_CFLAGS) -x c /dev/null -c -o > "$$TMPO"; \ > - $(LD) $(LDFLAGS) $(1) "$$TMPO" -o "$$TMP",$(1),$(2)) > +ld-option = $(call try-run-cached, $(LD) $(LDFLAGS) $(1) -v,$(1),$(2)) > # ar-option > # Usage: KBUILD_ARFLAGS := $(call ar-option,D) > -- > 2.7.4 -- Thanks, ~Nick Desaulniers