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From: Sami Tolvanen <samitolvanen@google.com>
To: Nathan Chancellor <natechancellor@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	Will Deacon <will@kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	clang-built-linux <clang-built-linux@googlegroups.com>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	linux-arch <linux-arch@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	linux-kbuild <linux-kbuild@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	PCI <linux-pci@vger.kernel.org>, Jian Cai <jiancai@google.com>,
	Kristof Beyls <Kristof.Beyls@arm.com>
Subject: Re: [PATCH v8 00/16] Add support for Clang LTO
Date: Sun, 6 Dec 2020 12:09:31 -0800	[thread overview]
Message-ID: <CABCJKue9TJnhge6TVPj9vfZXPGD4RW2JYiN3kNwVKNovTCq8ZA@mail.gmail.com> (raw)
In-Reply-To: <20201206065028.GA2819096@ubuntu-m3-large-x86>

On Sat, Dec 5, 2020 at 10:50 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Fri, Dec 04, 2020 at 02:52:41PM -0800, Sami Tolvanen wrote:
> > On Thu, Dec 3, 2020 at 2:32 PM Nick Desaulniers <ndesaulniers@google.com> wrote:
> > >
> > > So I'd recommend to Sami to simply make the Kconfig also depend on
> > > clang's integrated assembler (not just llvm-nm and llvm-ar).
> >
> > Sure, sounds good to me. What's the preferred way to test for this in Kconfig?
> >
> > It looks like actually trying to test if we have an LLVM assembler
> > (e.g. using $(as-instr,.section
> > ".linker-options","e",@llvm_linker_options)) doesn't work as Kconfig
> > doesn't pass -no-integrated-as to clang here.

After a closer look, that's actually not correct, this seems to work
with Clang+LLD no matter which assembler is used. I suppose we could
test for .gasversion. to detect GNU as, but that's hardly ideal.

> >I could do something
> > simple like $(success,echo $(LLVM) $(LLVM_IAS) | grep -q "1 1").
> >
> > Thoughts?
> >
> > Sami
>
> I think
>
>     depends on $(success,test $(LLVM_IAS) -eq 1)
>
> should work, at least according to my brief test.

Sure, looks good to me. However, I think we should also test for
LLVM=1 to avoid possible further issues with mismatched toolchains
instead of only checking for llvm-nm and llvm-ar.

Sami

  reply	other threads:[~2020-12-06 20:10 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-01 21:36 [PATCH v8 00/16] Add support for Clang LTO Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 01/16] tracing: move function tracer options to Kconfig Sami Tolvanen
2020-12-01 21:47   ` Steven Rostedt
2020-12-01 21:36 ` [PATCH v8 02/16] kbuild: add support for Clang LTO Sami Tolvanen
2020-12-02  2:59   ` Masahiro Yamada
2020-12-03  0:07   ` Nick Desaulniers
2020-12-01 21:36 ` [PATCH v8 03/16] kbuild: lto: fix module versioning Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 04/16] kbuild: lto: limit inlining Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 05/16] kbuild: lto: merge module sections Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 06/16] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 07/16] init: lto: ensure initcall ordering Sami Tolvanen
2020-12-01 21:36 ` [PATCH v8 08/16] init: lto: fix PREL32 relocations Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 09/16] PCI: Fix PREL32 relocations for LTO Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 10/16] modpost: lto: strip .lto from module names Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 11/16] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 12/16] efi/libstub: disable LTO Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 13/16] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 14/16] arm64: vdso: disable LTO Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 15/16] arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS Sami Tolvanen
2020-12-01 21:37 ` [PATCH v8 16/16] arm64: allow LTO to be selected Sami Tolvanen
2020-12-03  0:01 ` [PATCH v8 00/16] Add support for Clang LTO Nick Desaulniers
2020-12-03 11:26 ` Will Deacon
2020-12-03 17:07   ` Sami Tolvanen
2020-12-03 18:21     ` Nathan Chancellor
2020-12-03 18:22     ` Will Deacon
2020-12-03 22:32       ` Nick Desaulniers
2020-12-04  9:35         ` Will Deacon
2020-12-04 22:52         ` Sami Tolvanen
2020-12-06  6:50           ` Nathan Chancellor
2020-12-06 20:09             ` Sami Tolvanen [this message]
2020-12-08  0:46               ` Nathan Chancellor
2020-12-08 12:15 ` Arnd Bergmann
2020-12-08 13:54   ` Arnd Bergmann
2020-12-08 16:53     ` Sami Tolvanen
2020-12-08 16:56       ` Arnd Bergmann
2020-12-08 16:43   ` Sami Tolvanen
     [not found]     ` <CAK8P3a1Xfpt7QLkvxjtXKcgzcWkS8g9bmxD687+rqjTafTzKrg@mail.gmail.com>
2020-12-08 21:09       ` Nick Desaulniers
2020-12-08 22:20         ` Arnd Bergmann
2020-12-09 16:11           ` Sami Tolvanen
     [not found]       ` <CAK8P3a3O65m6Us=YvCP3QA+0kqAeEqfi-DLOJa+JYmBqs8-JcA@mail.gmail.com>
2020-12-09  5:23         ` Fāng-ruì Sòng
2020-12-09  9:07           ` Arnd Bergmann
2020-12-09 16:09         ` Sami Tolvanen
2020-12-09 19:24           ` Arnd Bergmann
2020-12-09  4:55     ` Fangrui Song
2020-12-09  9:19       ` Arnd Bergmann
2020-12-09 12:35   ` Arnd Bergmann
2020-12-09 16:25     ` Sami Tolvanen
2020-12-09 17:51       ` Arnd Bergmann

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