Re: [PATCH v2 1/2] Makefile: Remove '--gcc-toolchain' flag

From: Masahiro Yamada <masahiroy@kernel.org>
To: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	Fangrui Song <maskray@google.com>
Subject: Re: [PATCH v2 1/2] Makefile: Remove '--gcc-toolchain' flag
Date: Wed, 17 Mar 2021 00:36:11 +0900	[thread overview]
Message-ID: <CAK7LNATADzwnJt8vBQADGJjGe8jscRTAwvrLNc8AFgZ9SoWDUQ@mail.gmail.com> (raw)
In-Reply-To: <CA+icZUVRyEGnLnRBiZjmZqmvCLkR8AZR8tihho83Lrr_F9A2BA@mail.gmail.com>

On Tue, Mar 16, 2021 at 1:42 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Mon, Mar 15, 2021 at 5:22 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
> >
> > On Wed, Mar 10, 2021 at 5:59 AM Nathan Chancellor <nathan@kernel.org> wrote:
> > >
> > > This flag was originally added to allow clang to find the GNU cross
> > > tools in commit 785f11aa595b ("kbuild: Add better clang cross build
> > > support"). This flag was not enough to find the tools at times so
> > > '--prefix' was added to the list in commit ef8c4ed9db80 ("kbuild: allow
> > > to use GCC toolchain not in Clang search path") and improved upon in
> > > commit ca9b31f6bb9c ("Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang
> > > cross compilation"). Now that '--prefix' specifies a full path and
> > > prefix, '--gcc-toolchain' serves no purpose because the kernel builds
> > > with '-nostdinc' and '-nostdlib'.
> > >
> > > This has been verified with self compiled LLVM 10.0.1 and LLVM 13.0.0 as
> > > well as a distribution version of LLVM 11.1.0 without binutils in the
> > > LLVM toolchain locations.
> > >
> > > Link: https://reviews.llvm.org/D97902
> > > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> > > ---
> > >
> > > v1 -> v2:
> > >
> > > * Improve commit message (add history behind flag and link to Fangrui's
> > >   documentation improvement).
> >
> >
> > Both applied to linux-kbuild. Thanks.
> >
>
> Sorry for being pedantic: This misses my Tested-by#s (see [1]).
>
> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13-git
>
> AFAICS v2 changes some comments in the commit only but not code?

For 1/2, yes. The difference is only comments.

For 2/2, the code was changed.
Actually, v1 was wrong.
That is why the tags were dropped.

I will re-add the tags to 1/2
since there is no code diff.

If you re-test 2/2, I will add your tag again.

> - Sedat -
>
> [1] https://marc.info/?l=linux-kernel&m=161480031518629&w=2
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git/commit/?h=kbuild&id=d4aa405bc9cd506532f075456645716cdd1739c1
>
> >
> >
> >
> >
> > > I did not carry tags forward so that people could re-review and test.
> > >
> > >  Makefile | 4 ----
> > >  1 file changed, 4 deletions(-)
> > >
> > > diff --git a/Makefile b/Makefile
> > > index 31dcdb3d61fa..182e93d91198 100644
> > > --- a/Makefile
> > > +++ b/Makefile
> > > @@ -568,10 +568,6 @@ ifneq ($(CROSS_COMPILE),)
> > >  CLANG_FLAGS    += --target=$(notdir $(CROSS_COMPILE:%-=%))
> > >  GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
> > >  CLANG_FLAGS    += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
> > > -GCC_TOOLCHAIN  := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
> > > -endif
> > > -ifneq ($(GCC_TOOLCHAIN),)
> > > -CLANG_FLAGS    += --gcc-toolchain=$(GCC_TOOLCHAIN)
> > >  endif
> > >  ifneq ($(LLVM_IAS),1)
> > >  CLANG_FLAGS    += -no-integrated-as
> > >
> > > base-commit: a38fd8748464831584a19438cbb3082b5a2dab15
> > > --
> > > 2.31.0.rc1
> > >
> >
> >
> > --
> > Best Regards
> > Masahiro Yamada

-- 
Best Regards
Masahiro Yamada