Re: [PATCH 7/7] Kbuild: lto: pass -m32/-m64 to to LDFINAL

From: Arnd Bergmann <arnd@arndb.de>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Andi Kleen <ak@linux.intel.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Subject: Re: [PATCH 7/7] Kbuild: lto: pass -m32/-m64 to to LDFINAL
Date: Fri, 2 Feb 2018 21:18:57 +0100	[thread overview]
Message-ID: <CAK8P3a3dgFjXP3wub+J5-_67MS2Mm_twktD=cyoY2pPro+AWzQ@mail.gmail.com> (raw)
In-Reply-To: <nycvar.YSQ.7.76.1802021336090.1842@knanqh.ubzr>

On Fri, Feb 2, 2018 at 7:41 PM, Nicolas Pitre <nicolas.pitre@linaro.org> wrote:
> On Fri, 2 Feb 2018, Arnd Bergmann wrote:
>
>> Building randconfig kernels with a biarch compiler fails with LTO
>> when the final link uses a different target architecture compared
>> to the earlier compilation stages.
>>
>> Setting -m32 or -m64 in ${LDFINAL} solves this problem, though my
>> feeling is that there is a better way to do this. There might also
>> be other from KBUILD_CFLAGS that we may need in LDFINAL.
>
> On ARM I had the same problem as it requires explicit arch flags. I
> therefore used this patch:

> -exec $CC $ARGS
> +case "${KBUILD_VERBOSE}" in
> +*1*)
> +       set -x
> +       ;;
> +esac
> +
> +exec $CC $KBUILD_CFLAGS $ARGS

Ah, right, that's much simpler. I'll put that in my test tree now and
will see if it works on x86.

Do you have a git tree with other changes for LTO on ARM? I'd
like to try that as well.

       Arnd