linux-kernel - RE: [PATCH] ARC: Don't set CROSS

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Date:   Wed, 17 Oct 2018 14:33:02 +0000
From:   Alexey Brodkin <alexey.brodkin@...opsys.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Vineet Gupta" <vineet.gupta1@...opsys.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Rob Herring <robh@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>
Subject: RE: [PATCH] ARC: Don't set CROSS_COMPILE in arch's Makefile

Hello,

> -----Original Message-----
> From: Alexey Brodkin [mailto:abrodkin@...opsys.com]
> Sent: Sunday, September 16, 2018 11:48 PM
> To: linux-snps-arc@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org; Vineet Gupta <vgupta@...opsys.com>; Alexey Brodkin <abrodkin@...opsys.com>; Masahiro
> Yamada <yamada.masahiro@...ionext.com>; Rob Herring <robh@...nel.org>
> Subject: [PATCH] ARC: Don't set CROSS_COMPILE in arch's Makefile
> 
> There's not much sense in doing that because if user or
> his build-system didn't set CROSS_COMPILE we still may
> very well make incorrect guess.
> 
> But as it turned out setting CROSS_COMPILE is not as harmless
> as one may think: with recent changes that implemented automatic
> discovery of __host__ gcc features unconditional setup of
> CROSS_COMPILE leads to failures on execution of "make xxx_defconfig"
> with absent cross-compiler, for more info see [1].
> 
> Set CROSS_COMPILE as well gets in the way if we want only to build
> .dtb's (again with absent cross-compiler which is not really needed
> for building .dtb's), see [2].
> 
> Note, we had to change LIBGCC assignment type from ":=" to "="
> so that is is resolved on its usage, otherwise if it is resolved
> at declaration time with missing CROSS_COMPILE we're getting this
> error message from host GCC:
> ------------------------->8-------------------------
> gcc: error: unrecognized command line option ‘-mmedium-calls’
> gcc: error: unrecognized command line option ‘-mno-sdata’; did you mean ‘-fno-stats’?
> ------------------------->8-------------------------
> 
> [1] http://lists.infradead.org/pipermail/linux-snps-arc/2018-September/004308.html
> [2] http://lists.infradead.org/pipermail/linux-snps-arc/2018-September/004320.html
> 
> Signed-off-by: Alexey Brodkin <abrodkin@...opsys.com>
> Cc: Masahiro Yamada <yamada.masahiro@...ionext.com>
> Cc: Rob Herring <robh@...nel.org>
> ---
>  arch/arc/Makefile | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
> 
> diff --git a/arch/arc/Makefile b/arch/arc/Makefile
> index 99cce77ab98f..5f6b67917dc2 100644
> --- a/arch/arc/Makefile
> +++ b/arch/arc/Makefile
> @@ -6,14 +6,6 @@
>  # published by the Free Software Foundation.
>  #
> 
> -ifeq ($(CROSS_COMPILE),)
> -ifndef CONFIG_CPU_BIG_ENDIAN
> -CROSS_COMPILE := arc-linux-
> -else
> -CROSS_COMPILE := arceb-linux-
> -endif
> -endif
> -
>  KBUILD_DEFCONFIG := nsim_700_defconfig
> 
>  cflags-y	+= -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__
> @@ -79,7 +71,7 @@ cflags-$(disable_small_data)		+= -mno-sdata -fcall-used-gp
>  cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= -mbig-endian
>  ldflags-$(CONFIG_CPU_BIG_ENDIAN)	+= -EB
> 
> -LIBGCC	:= $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
> +LIBGCC	= $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
> 
>  # Modules with short calls might break for calls into builtin-kernel
>  KBUILD_CFLAGS_MODULE	+= -mlong-calls -mno-millicode
> --
> 2.17.1

May we have this one back-ported to stable branches?

Upstream commit in Linus' tree is:
40660f1fcee8 ("ARC: build: Don't set CROSS_COMPILE in arch's Makefile").

Regards,
Alexey